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5.20 cleanups and poll optimisations

PATCH Superseded Pavel Begunkov 2 participants 30 messages Jun 14, 2022 io_uring

v1 of 3 Superseded Latest is v3 →

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Pavel Begunkov

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#0 lore raw

cover 5.20 cleanups and poll optimisations

1-13 are cleanups after splitting io_uring into files.

Patch 14 from Hao should remove some overhead from poll requests

Patch 15 from Hao adds per-bucket spinlocks, and 16-19 do a little bit of cleanup. The downside of per-bucket spinlocks is that it adds additional spinlock/unlock pair in the poll request completion side, which shouldn't matter much with 20/25.

Patch 20 uses inline completion infra for poll requests, this nicely improves perf when there is a good tw batching.

Patch 21 implements the userspace visible side of IORING_SETUP_SINGLE_ISSUER, it'll be used for poll requests and later for spinlock optimisations.

22-25 introduces ->uring_lock protected cancellation hashing. It requires us to grab ->uring_lock in the completion side, but saves two spin lock/unlock pairs. We apply it automatically in cases the mutex is already likely to be held (see 25/25 description), so there is no additional mutex overhead and potential latency problemes.

Numbers:

I used a simple poll benchmark temporarily stored at [1], which each iteration queues a batch of 32 POLLIN poll requests and triggers all of them with read (+write).

baseline (patches 1-18):

    11720 K req/s
base + 19 (+ inline completion infra)
    12419 K req/s, ~+6%
base + 19-25 (+ uring_lock hashing):
    12804 K req/s, +9.2% from the baseline, or +3.2% relative to patch 19.

[1] https://github.com/isilence/liburing/tree/poll-bench

Hao Xu (2):
io_uring: poll: remove unnecessary req->ref set
io_uring: switch cancel_hash to use per entry spinlock

Pavel Begunkov (23):
io_uring: make reg buf init consistent
io_uring: move defer_list to slow data
io_uring: better caching for ctx timeout fields
io_uring: refactor ctx slow data placement
io_uring: move cancel_seq out of io-wq
io_uring: move small helpers to headers
io_uring: inline ->registered_rings
io_uring: don't set REQ_F_COMPLETE_INLINE in tw
io_uring: never defer-complete multi-apoll
io_uring: kill REQ_F_COMPLETE_INLINE
io_uring: refactor io_req_task_complete()
io_uring: don't inline io_put_kbuf
io_uring: remove check_cq checking from hot paths
io_uring: pass poll_find lock back
io_uring: clean up io_try_cancel
io_uring: limit number hash buckets
io_uring: clean up io_ring_ctx_alloc
io_uring: use state completion infra for poll reqs
io_uring: add IORING_SETUP_SINGLE_ISSUER
io_uring: pass hash table into poll_find
io_uring: introduce a struct for hash table
io_uring: propagate locking state to poll cancel
io_uring: mutex locked poll hashing

 include/uapi/linux/io_uring.h |   5 +-
 io_uring/cancel.c             |  27 ++--
 io_uring/cancel.h             |   4 +-
 io_uring/fdinfo.c             |  11 +-
 io_uring/io-wq.h              |   1 -
 io_uring/io_uring.c           | 149 +++++++++++-----------
 io_uring/io_uring.h           |  17 +++
 io_uring/io_uring_types.h     | 109 +++++++++-------
 io_uring/kbuf.c               |  33 +++++
 io_uring/kbuf.h               |  38 +-----
 io_uring/poll.c               | 229 ++++++++++++++++++++++++----------
 io_uring/poll.h               |   3 +-
 io_uring/rsrc.c               |   9 +-
 io_uring/tctx.c               |  34 +++--
 io_uring/tctx.h               |   7 +-
 io_uring/timeout.c            |   7 +-
 16 files changed, 426 insertions(+), 257 deletions(-)
Signature · 1 line
2.36.1
author
#1 lore raw

PATCH 1/25 io_uring: make reg buf init consistent

The default (i.e. empty) state of register buffer is dummy_ubuf, so set it to dummy on init instead of NULL.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/rsrc.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)
io_uring/rsrc.c +3 -6
index fef46972c327..fd1323482030 100644
@@ -567,7 +567,7 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
 				io_buffer_unmap(ctx, &imu);
 				break;
 			}
-			ctx->user_bufs[i] = NULL;
+			ctx->user_bufs[i] = ctx->dummy_ubuf;
 			needs_switch = true;
 		}
 

@@ -1200,14 +1200,11 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
 	size_t size;
 	int ret, nr_pages, i;
 
-	if (!iov->iov_base) {
-		*pimu = ctx->dummy_ubuf;
+	*pimu = ctx->dummy_ubuf;
+	if (!iov->iov_base)
 		return 0;
-	}
 
-	*pimu = NULL;
 	ret = -ENOMEM;
-
 	pages = io_pin_pages((unsigned long) iov->iov_base, iov->iov_len,
 				&nr_pages);
 	if (IS_ERR(pages)) {
Signature · 1 line
2.36.1
author
#2 lore raw

PATCH 2/25 io_uring: move defer_list to slow data

In reply to Pavel Begunkov

draining is slow path, move defer_list to the end where slow data lives inside the context.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring_types.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
io_uring/io_uring_types.h +4 -1
index 7c22cf35a7e2..52e91c3df8d5 100644
@@ -160,7 +160,6 @@ struct io_ring_ctx {
 		struct io_uring_sqe	*sq_sqes;
 		unsigned		cached_sq_head;
 		unsigned		sq_entries;
-		struct list_head	defer_list;
 
 		/*
 		 * Fixed resources fast path, should be accessed only under

@@ -272,8 +271,12 @@ struct io_ring_ctx {
 		struct work_struct		exit_work;
 		struct list_head		tctx_list;
 		struct completion		ref_comp;
+
+		/* io-wq management, e.g. thread count */
 		u32				iowq_limits[2];
 		bool				iowq_limits_set;
+
+		struct list_head		defer_list;
 	};
 };
Signature · 1 line
2.36.1
author
#3 lore raw

PATCH 3/25 io_uring: better caching for ctx timeout fields

In reply to Pavel Begunkov

Following timeout fields access patterns, move all of them into a separate cache line inside ctx, so they don't intervene with normal completion caching, especially since timeout removals and completion are separated and the later is done via tw.

It also sheds some bytes from io_ring_ctx, 1216B -> 1152B

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring_types.h | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)
io_uring/io_uring_types.h +9 -6
index 52e91c3df8d5..4f52dcbbda56 100644
@@ -179,8 +179,6 @@ struct io_ring_ctx {
 		struct xarray		io_bl_xa;
 		struct list_head	io_buffers_cache;
 
-		struct list_head	timeout_list;
-		struct list_head	ltimeout_list;
 		struct list_head	cq_overflow_list;
 		struct list_head	apoll_cache;
 		struct xarray		personalities;

@@ -213,15 +211,11 @@ struct io_ring_ctx {
 		struct io_ev_fd	__rcu	*io_ev_fd;
 		struct wait_queue_head	cq_wait;
 		unsigned		cq_extra;
-		atomic_t		cq_timeouts;
-		unsigned		cq_last_tm_flush;
 	} ____cacheline_aligned_in_smp;
 
 	struct {
 		spinlock_t		completion_lock;
 
-		spinlock_t		timeout_lock;
-
 		/*
 		 * ->iopoll_list is protected by the ctx->uring_lock for
 		 * io_uring instances that don't use IORING_SETUP_SQPOLL.

@@ -253,6 +247,15 @@ struct io_ring_ctx {
 		struct list_head	io_buffers_pages;
 	};
 
+	/* timeouts */
+	struct {
+		spinlock_t		timeout_lock;
+		atomic_t		cq_timeouts;
+		struct list_head	timeout_list;
+		struct list_head	ltimeout_list;
+		unsigned		cq_last_tm_flush;
+	} ____cacheline_aligned_in_smp;
+
 	/* Keep this last, we don't need it for the fast path */
 	struct {
 		#if defined(CONFIG_UNIX)
Signature · 1 line
2.36.1
author
#4 lore raw

PATCH 4/25 io_uring: refactor ctx slow data placement

In reply to Pavel Begunkov

Shove all slow path data at the end of ctx and get rid of extra indention.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring_types.h | 81 +++++++++++++++++++--------------------
 1 file changed, 39 insertions(+), 42 deletions(-)
io_uring/io_uring_types.h +39 -42
index 4f52dcbbda56..ca8e25992ece 100644
@@ -183,7 +183,6 @@ struct io_ring_ctx {
 		struct list_head	apoll_cache;
 		struct xarray		personalities;
 		u32			pers_next;
-		unsigned		sq_thread_idle;
 	} ____cacheline_aligned_in_smp;
 
 	/* IRQ completion list, under ->completion_lock */

@@ -230,23 +229,6 @@ struct io_ring_ctx {
 		struct list_head	io_buffers_comp;
 	} ____cacheline_aligned_in_smp;
 
-	struct io_restriction		restrictions;
-
-	/* slow path rsrc auxilary data, used by update/register */
-	struct {
-		struct io_rsrc_node		*rsrc_backup_node;
-		struct io_mapped_ubuf		*dummy_ubuf;
-		struct io_rsrc_data		*file_data;
-		struct io_rsrc_data		*buf_data;
-
-		struct delayed_work		rsrc_put_work;
-		struct llist_head		rsrc_put_llist;
-		struct list_head		rsrc_ref_list;
-		spinlock_t			rsrc_ref_lock;
-
-		struct list_head	io_buffers_pages;
-	};
-
 	/* timeouts */
 	struct {
 		spinlock_t		timeout_lock;

@@ -257,30 +239,45 @@ struct io_ring_ctx {
 	} ____cacheline_aligned_in_smp;
 
 	/* Keep this last, we don't need it for the fast path */
-	struct {
-		#if defined(CONFIG_UNIX)
-			struct socket		*ring_sock;
-		#endif
-		/* hashed buffered write serialization */
-		struct io_wq_hash		*hash_map;
-
-		/* Only used for accounting purposes */
-		struct user_struct		*user;
-		struct mm_struct		*mm_account;
-
-		/* ctx exit and cancelation */
-		struct llist_head		fallback_llist;
-		struct delayed_work		fallback_work;
-		struct work_struct		exit_work;
-		struct list_head		tctx_list;
-		struct completion		ref_comp;
-
-		/* io-wq management, e.g. thread count */
-		u32				iowq_limits[2];
-		bool				iowq_limits_set;
-
-		struct list_head		defer_list;
-	};
+
+	struct io_restriction		restrictions;
+
+	/* slow path rsrc auxilary data, used by update/register */
+	struct io_rsrc_node		*rsrc_backup_node;
+	struct io_mapped_ubuf		*dummy_ubuf;
+	struct io_rsrc_data		*file_data;
+	struct io_rsrc_data		*buf_data;
+
+	struct delayed_work		rsrc_put_work;
+	struct llist_head		rsrc_put_llist;
+	struct list_head		rsrc_ref_list;
+	spinlock_t			rsrc_ref_lock;
+
+	struct list_head		io_buffers_pages;
+
+	#if defined(CONFIG_UNIX)
+		struct socket		*ring_sock;
+	#endif
+	/* hashed buffered write serialization */
+	struct io_wq_hash		*hash_map;
+
+	/* Only used for accounting purposes */
+	struct user_struct		*user;
+	struct mm_struct		*mm_account;
+
+	/* ctx exit and cancelation */
+	struct llist_head		fallback_llist;
+	struct delayed_work		fallback_work;
+	struct work_struct		exit_work;
+	struct list_head		tctx_list;
+	struct completion		ref_comp;
+
+	/* io-wq management, e.g. thread count */
+	u32				iowq_limits[2];
+	bool				iowq_limits_set;
+
+	struct list_head		defer_list;
+	unsigned			sq_thread_idle;
 };
 
 enum {
Signature · 1 line
2.36.1
author
#5 lore raw

PATCH 5/25 io_uring: move cancel_seq out of io-wq

In reply to Pavel Begunkov

io-wq doesn't use ->cancel_seq, it's only important to io_uring and should be stored there.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/cancel.c         |  4 ++--
 io_uring/io-wq.h          |  1 -
 io_uring/io_uring.c       |  2 +-
 io_uring/io_uring_types.h |  1 +
 io_uring/poll.c           | 10 +++++-----
 io_uring/timeout.c        |  4 ++--
 6 files changed, 11 insertions(+), 11 deletions(-)
io_uring/cancel.c +2 -2
index 83cceb52d82d..2e72231882b7 100644
@@ -44,9 +44,9 @@ static bool io_cancel_cb(struct io_wq_work *work, void *data)
 			return false;
 	}
 	if (cd->flags & (IORING_ASYNC_CANCEL_ALL|IORING_ASYNC_CANCEL_ANY)) {
-		if (cd->seq == req->work.cancel_seq)
+		if (cd->seq == req->cancel_seq)
 			return false;
-		req->work.cancel_seq = cd->seq;
+		req->cancel_seq = cd->seq;
 	}
 	return true;
 }
io_uring/io-wq.h +0 -1
index ba6eee76d028..dbecd27656c7 100644
@@ -155,7 +155,6 @@ struct io_wq_work_node *wq_stack_extract(struct io_wq_work_node *stack)
 struct io_wq_work {
 	struct io_wq_work_node list;
 	unsigned flags;
-	int cancel_seq;
 };
 
 static inline struct io_wq_work *wq_next_work(struct io_wq_work *work)
io_uring/io_uring.c +1 -1
index 6a94d1682aaf..af9188c8e2eb 100644
@@ -849,7 +849,7 @@ static void io_prep_async_work(struct io_kiocb *req)
 
 	req->work.list.next = NULL;
 	req->work.flags = 0;
-	req->work.cancel_seq = atomic_read(&ctx->cancel_seq);
+	req->cancel_seq = atomic_read(&ctx->cancel_seq);
 	if (req->flags & REQ_F_FORCE_ASYNC)
 		req->work.flags |= IO_WQ_WORK_CONCURRENT;
io_uring/io_uring_types.h +1 -0
index ca8e25992ece..25e07c3f7b2a 100644
@@ -486,6 +486,7 @@ struct io_kiocb {
 	/* custom credentials, valid IFF REQ_F_CREDS is set */
 	const struct cred		*creds;
 	struct io_wq_work		work;
+	int				cancel_seq;
 };
 
 struct io_cancel_data {
io_uring/poll.c +5 -5
index 0df5eca93b16..b46973140ffd 100644
@@ -405,7 +405,7 @@ static int __io_arm_poll_handler(struct io_kiocb *req,
 	int v;
 
 	INIT_HLIST_NODE(&req->hash_node);
-	req->work.cancel_seq = atomic_read(&ctx->cancel_seq);
+	req->cancel_seq = atomic_read(&ctx->cancel_seq);
 	io_init_poll_iocb(poll, mask, io_poll_wake);
 	poll->file = req->file;
 

@@ -565,9 +565,9 @@ static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only,
 		if (poll_only && req->opcode != IORING_OP_POLL_ADD)
 			continue;
 		if (cd->flags & IORING_ASYNC_CANCEL_ALL) {
-			if (cd->seq == req->work.cancel_seq)
+			if (cd->seq == req->cancel_seq)
 				continue;
-			req->work.cancel_seq = cd->seq;
+			req->cancel_seq = cd->seq;
 		}
 		return req;
 	}

@@ -589,9 +589,9 @@ static struct io_kiocb *io_poll_file_find(struct io_ring_ctx *ctx,
 			if (!(cd->flags & IORING_ASYNC_CANCEL_ANY) &&
 			    req->file != cd->file)
 				continue;
-			if (cd->seq == req->work.cancel_seq)
+			if (cd->seq == req->cancel_seq)
 				continue;
-			req->work.cancel_seq = cd->seq;
+			req->cancel_seq = cd->seq;
 			return req;
 		}
 	}
io_uring/timeout.c +2 -2
index 69cca42d6835..89000aae65d9 100644
@@ -227,9 +227,9 @@ static struct io_kiocb *io_timeout_extract(struct io_ring_ctx *ctx,
 		    cd->data != tmp->cqe.user_data)
 			continue;
 		if (cd->flags & (IORING_ASYNC_CANCEL_ALL|IORING_ASYNC_CANCEL_ANY)) {
-			if (cd->seq == tmp->work.cancel_seq)
+			if (cd->seq == tmp->cancel_seq)
 				continue;
-			tmp->work.cancel_seq = cd->seq;
+			tmp->cancel_seq = cd->seq;
 		}
 		req = tmp;
 		break;
Signature · 1 line
2.36.1
maintainer
#6 lore raw

Re: [PATCH for-next 05/25] io_uring: move cancel_seq out of io-wq

Quoted 2 lines · Pavel Begunkov

io-wq doesn't use ->cancel_seq, it's only important to io_uring and should be stored there.

It isn't there because it's io-wq only, but to save space. This adds 8 bytes to io_kiocb, as far as I can tell?

Signature · 1 line
Jens Axboe
author
#7 lore raw

Re: [PATCH for-next 05/25] io_uring: move cancel_seq out of io-wq

Quoted 6 lines · Jens Axboe
Quoted 2 lines · Pavel Begunkov

io-wq doesn't use ->cancel_seq, it's only important to io_uring and should be stored there.

It isn't there because it's io-wq only, but to save space. This adds 8 bytes to io_kiocb, as far as I can tell?

Ah ok, makes sense. It's worth a comment though

Signature · 1 line
Pavel Begunkov
maintainer
#8 lore raw

Re: [PATCH for-next 05/25] io_uring: move cancel_seq out of io-wq

Quoted 9 lines · Pavel Begunkov
Quoted 6 lines · Jens Axboe
Quoted 2 lines · Pavel Begunkov

io-wq doesn't use ->cancel_seq, it's only important to io_uring and should be stored there.

It isn't there because it's io-wq only, but to save space. This adds 8 bytes to io_kiocb, as far as I can tell?

Ah ok, makes sense. It's worth a comment though

Definitely, not sure why I didn't add one... When you respin the series, maybe change this patch to add that comment instead?

Signature · 1 line
Jens Axboe
author
#9 lore raw

PATCH 6/25 io_uring: move small helpers to headers

In reply to Pavel Begunkov

There is a bunch of inline helpers that will be useful not only to the core of io_uring, move them to headers.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring.c | 22 ----------------------
 io_uring/io_uring.h | 22 ++++++++++++++++++++++
 2 files changed, 22 insertions(+), 22 deletions(-)
io_uring/io_uring.c +0 -22
index af9188c8e2eb..2f5fd1749c4a 100644
@@ -616,14 +616,6 @@ struct sock *io_uring_get_socket(struct file *file)
 }
 EXPORT_SYMBOL(io_uring_get_socket);
 
-static inline void io_tw_lock(struct io_ring_ctx *ctx, bool *locked)
-{
-	if (!*locked) {
-		mutex_lock(&ctx->uring_lock);
-		*locked = true;
-	}
-}
-
 static inline void io_submit_flush_completions(struct io_ring_ctx *ctx)
 {
 	if (!wq_list_empty(&ctx->submit_state.compl_reqs))

@@ -879,15 +871,6 @@ static void io_prep_async_link(struct io_kiocb *req)
 	}
 }
 
-static inline void io_req_add_compl_list(struct io_kiocb *req)
-{
-	struct io_submit_state *state = &req->ctx->submit_state;
-
-	if (!(req->flags & REQ_F_CQE_SKIP))
-		state->flush_cqes = true;
-	wq_list_add_tail(&req->comp_list, &state->compl_reqs);
-}
-
 void io_queue_iowq(struct io_kiocb *req, bool *dont_use)
 {
 	struct io_kiocb *link = io_prep_linked_timeout(req);

@@ -1293,11 +1276,6 @@ static void io_req_complete_post32(struct io_kiocb *req, u64 extra1, u64 extra2)
 	io_cqring_ev_posted(ctx);
 }
 
-static inline void io_req_complete_state(struct io_kiocb *req)
-{
-	req->flags |= REQ_F_COMPLETE_INLINE;
-}
-
 inline void __io_req_complete(struct io_kiocb *req, unsigned issue_flags)
 {
 	if (issue_flags & IO_URING_F_COMPLETE_DEFER)
io_uring/io_uring.h +22 -0
index 3660df80e589..26b669746d61 100644
@@ -193,6 +193,28 @@ static inline bool io_run_task_work(void)
 	return false;
 }
 
+static inline void io_req_complete_state(struct io_kiocb *req)
+{
+	req->flags |= REQ_F_COMPLETE_INLINE;
+}
+
+static inline void io_tw_lock(struct io_ring_ctx *ctx, bool *locked)
+{
+	if (!*locked) {
+		mutex_lock(&ctx->uring_lock);
+		*locked = true;
+	}
+}
+
+static inline void io_req_add_compl_list(struct io_kiocb *req)
+{
+	struct io_submit_state *state = &req->ctx->submit_state;
+
+	if (!(req->flags & REQ_F_CQE_SKIP))
+		state->flush_cqes = true;
+	wq_list_add_tail(&req->comp_list, &state->compl_reqs);
+}
+
 int io_run_task_work_sig(void);
 void io_req_complete_failed(struct io_kiocb *req, s32 res);
 void __io_req_complete32(struct io_kiocb *req, unsigned int issue_flags,
Signature · 1 line
2.36.1
author
#10 lore raw

PATCH 7/25 io_uring: inline ->registered_rings

In reply to Pavel Begunkov

There can be only 16 registered rings, no need to allocate an array for them separately but store it in tctx.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring.c | 1 -
 io_uring/tctx.c     | 9 ---------
 io_uring/tctx.h     | 3 ++-
 3 files changed, 2 insertions(+), 11 deletions(-)
io_uring/io_uring.c +0 -1
index 2f5fd1749c4a..2efe6bd16e07 100644
@@ -2840,7 +2840,6 @@ void __io_uring_free(struct task_struct *tsk)
 	WARN_ON_ONCE(tctx->io_wq);
 	WARN_ON_ONCE(tctx->cached_refs);
 
-	kfree(tctx->registered_rings);
 	percpu_counter_destroy(&tctx->inflight);
 	kfree(tctx);
 	tsk->io_uring = NULL;
io_uring/tctx.c +0 -9
index f3262eef55d4..6adf659687f8 100644
@@ -55,16 +55,8 @@ __cold int io_uring_alloc_task_context(struct task_struct *task,
 	if (unlikely(!tctx))
 		return -ENOMEM;
 
-	tctx->registered_rings = kcalloc(IO_RINGFD_REG_MAX,
-					 sizeof(struct file *), GFP_KERNEL);
-	if (unlikely(!tctx->registered_rings)) {
-		kfree(tctx);
-		return -ENOMEM;
-	}
-
 	ret = percpu_counter_init(&tctx->inflight, 0, GFP_KERNEL);
 	if (unlikely(ret)) {
-		kfree(tctx->registered_rings);
 		kfree(tctx);
 		return ret;
 	}

@@ -73,7 +65,6 @@ __cold int io_uring_alloc_task_context(struct task_struct *task,
 	if (IS_ERR(tctx->io_wq)) {
 		ret = PTR_ERR(tctx->io_wq);
 		percpu_counter_destroy(&tctx->inflight);
-		kfree(tctx->registered_rings);
 		kfree(tctx);
 		return ret;
 	}
io_uring/tctx.h +2 -1
index f4964e40d07e..7684713e950f 100644
@@ -20,8 +20,9 @@ struct io_uring_task {
 	struct io_wq_work_list	task_list;
 	struct io_wq_work_list	prio_task_list;
 	struct callback_head	task_work;
-	struct file		**registered_rings;
 	bool			task_running;
+
+	struct file		*registered_rings[IO_RINGFD_REG_MAX];
 };
 
 struct io_tctx_node {
Signature · 1 line
2.36.1
author
#11 lore raw

PATCH 8/25 io_uring: don't set REQ_F_COMPLETE_INLINE in tw

In reply to Pavel Begunkov

io_req_task_complete() enqueues requests for state completion itself, no need for REQ_F_COMPLETE_INLINE, which is only serve the purpose of not bloating the kernel.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring.c | 1 -
 1 file changed, 1 deletion(-)
io_uring/io_uring.c +0 -1
index 2efe6bd16e07..8ce8d2516704 100644
@@ -1864,7 +1864,6 @@ inline void io_req_task_complete(struct io_kiocb *req, bool *locked)
 {
 	if (*locked) {
 		req->cqe.flags |= io_put_kbuf(req, 0);
-		io_req_complete_state(req);
 		io_req_add_compl_list(req);
 	} else {
 		req->cqe.flags |= io_put_kbuf(req, IO_URING_F_UNLOCKED);
Signature · 1 line
2.36.1
author
#12 lore raw

PATCH 9/25 io_uring: never defer-complete multi-apoll

In reply to Pavel Begunkov

Luckily, nnobody completes multi-apoll requests outside the polling functions, but don't set IO_URING_F_COMPLETE_DEFER in any case as there is nobody who is catching REQ_F_COMPLETE_INLINE, and so will leak requests if used.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
io_uring/io_uring.c +1 -1
index 8ce8d2516704..5156844ca2bb 100644
@@ -2149,7 +2149,7 @@ int io_poll_issue(struct io_kiocb *req, bool *locked)
 	io_tw_lock(req->ctx, locked);
 	if (unlikely(req->task->flags & PF_EXITING))
 		return -EFAULT;
-	return io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_COMPLETE_DEFER);
+	return io_issue_sqe(req, IO_URING_F_NONBLOCK);
 }
 
 struct io_wq_work *io_wq_free_work(struct io_wq_work *work)
Signature · 1 line
2.36.1
author
#13 lore raw

PATCH 10/25 io_uring: kill REQ_F_COMPLETE_INLINE

In reply to Pavel Begunkov

REQ_F_COMPLETE_INLINE is only needed to delay queueing into the completion list to io_queue_sqe() as __io_req_complete() is inlined and we don't want to bloat the kernel.

As now we complete in a more centralised fashion in io_issue_sqe() we can get rid of the flag and queue to the list directly.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring.c       | 20 ++++++++------------
 io_uring/io_uring.h       |  5 -----
 io_uring/io_uring_types.h |  3 ---
 3 files changed, 8 insertions(+), 20 deletions(-)
io_uring/io_uring.c +8 -12
index 5156844ca2bb..6c48d0c6dcd5 100644
@@ -1278,17 +1278,14 @@ static void io_req_complete_post32(struct io_kiocb *req, u64 extra1, u64 extra2)
 
 inline void __io_req_complete(struct io_kiocb *req, unsigned issue_flags)
 {
-	if (issue_flags & IO_URING_F_COMPLETE_DEFER)
-		io_req_complete_state(req);
-	else
-		io_req_complete_post(req);
+	io_req_complete_post(req);
 }
 
 void __io_req_complete32(struct io_kiocb *req, unsigned int issue_flags,
 			 u64 extra1, u64 extra2)
 {
 	if (issue_flags & IO_URING_F_COMPLETE_DEFER) {
-		io_req_complete_state(req);
+		io_req_add_compl_list(req);
 		req->extra1 = extra1;
 		req->extra2 = extra2;
 	} else {

@@ -2132,9 +2129,12 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 	if (creds)
 		revert_creds(creds);
 
-	if (ret == IOU_OK)
-		__io_req_complete(req, issue_flags);
-	else if (ret != IOU_ISSUE_SKIP_COMPLETE)
+	if (ret == IOU_OK) {
+		if (issue_flags & IO_URING_F_COMPLETE_DEFER)
+			io_req_add_compl_list(req);
+		else
+			io_req_complete_post(req);
+	} else if (ret != IOU_ISSUE_SKIP_COMPLETE)
 		return ret;
 
 	/* If the op doesn't have a file, we're not polling for it */

@@ -2299,10 +2299,6 @@ static inline void io_queue_sqe(struct io_kiocb *req)
 
 	ret = io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_COMPLETE_DEFER);
 
-	if (req->flags & REQ_F_COMPLETE_INLINE) {
-		io_req_add_compl_list(req);
-		return;
-	}
 	/*
 	 * We async punt it if the file wasn't marked NOWAIT, or if the file
 	 * doesn't support non-blocking read/write attempts
io_uring/io_uring.h +0 -5
index 26b669746d61..2141519e995a 100644
@@ -193,11 +193,6 @@ static inline bool io_run_task_work(void)
 	return false;
 }
 
-static inline void io_req_complete_state(struct io_kiocb *req)
-{
-	req->flags |= REQ_F_COMPLETE_INLINE;
-}
-
 static inline void io_tw_lock(struct io_ring_ctx *ctx, bool *locked)
 {
 	if (!*locked) {
io_uring/io_uring_types.h +0 -3
index 25e07c3f7b2a..3cf06f4a4d2e 100644
@@ -299,7 +299,6 @@ enum {
 	REQ_F_POLLED_BIT,
 	REQ_F_BUFFER_SELECTED_BIT,
 	REQ_F_BUFFER_RING_BIT,
-	REQ_F_COMPLETE_INLINE_BIT,
 	REQ_F_REISSUE_BIT,
 	REQ_F_CREDS_BIT,
 	REQ_F_REFCOUNT_BIT,

@@ -353,8 +352,6 @@ enum {
 	REQ_F_BUFFER_SELECTED	= BIT(REQ_F_BUFFER_SELECTED_BIT),
 	/* buffer selected from ring, needs commit */
 	REQ_F_BUFFER_RING	= BIT(REQ_F_BUFFER_RING_BIT),
-	/* completion is deferred through io_comp_state */
-	REQ_F_COMPLETE_INLINE	= BIT(REQ_F_COMPLETE_INLINE_BIT),
 	/* caller should reissue async */
 	REQ_F_REISSUE		= BIT(REQ_F_REISSUE_BIT),
 	/* supports async reads/writes */
Signature · 1 line
2.36.1
author
#14 lore raw

PATCH 11/25 io_uring: refactor io_req_task_complete()

In reply to Pavel Begunkov

Clean up io_req_task_complete() and deduplicate io_put_kbuf() calls.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)
io_uring/io_uring.c +10 -6
index 6c48d0c6dcd5..f3cae98471b8 100644
@@ -1857,15 +1857,19 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
 
 	return ret;
 }
-inline void io_req_task_complete(struct io_kiocb *req, bool *locked)
+
+void io_req_task_complete(struct io_kiocb *req, bool *locked)
 {
-	if (*locked) {
-		req->cqe.flags |= io_put_kbuf(req, 0);
+	if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) {
+		unsigned issue_flags = *locked ? IO_URING_F_UNLOCKED : 0;
+
+		req->cqe.flags |= io_put_kbuf(req, issue_flags);
+	}
+
+	if (*locked)
 		io_req_add_compl_list(req);
-	} else {
-		req->cqe.flags |= io_put_kbuf(req, IO_URING_F_UNLOCKED);
+	else
 		io_req_complete_post(req);
-	}
 }
 
 /*
Signature · 1 line
2.36.1
author
#15 lore raw

PATCH 12/25 io_uring: don't inline io_put_kbuf

In reply to Pavel Begunkov

io_put_kbuf() is huge, don't bloat the kernel with inlining.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/kbuf.c | 33 +++++++++++++++++++++++++++++++++
 io_uring/kbuf.h | 38 ++++++--------------------------------
 2 files changed, 39 insertions(+), 32 deletions(-)
io_uring/kbuf.c +33 -0
index 9cdbc018fd64..6f2adb481a0d 100644
@@ -81,6 +81,39 @@ static int io_buffer_add_list(struct io_ring_ctx *ctx,
 	return xa_err(xa_store(&ctx->io_bl_xa, bgid, bl, GFP_KERNEL));
 }
 
+unsigned int __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags)
+{
+	unsigned int cflags;
+
+	/*
+	 * We can add this buffer back to two lists:
+	 *
+	 * 1) The io_buffers_cache list. This one is protected by the
+	 *    ctx->uring_lock. If we already hold this lock, add back to this
+	 *    list as we can grab it from issue as well.
+	 * 2) The io_buffers_comp list. This one is protected by the
+	 *    ctx->completion_lock.
+	 *
+	 * We migrate buffers from the comp_list to the issue cache list
+	 * when we need one.
+	 */
+	if (req->flags & REQ_F_BUFFER_RING) {
+		/* no buffers to recycle for this case */
+		cflags = __io_put_kbuf_list(req, NULL);
+	} else if (issue_flags & IO_URING_F_UNLOCKED) {
+		struct io_ring_ctx *ctx = req->ctx;
+
+		spin_lock(&ctx->completion_lock);
+		cflags = __io_put_kbuf_list(req, &ctx->io_buffers_comp);
+		spin_unlock(&ctx->completion_lock);
+	} else {
+		lockdep_assert_held(&req->ctx->uring_lock);
+
+		cflags = __io_put_kbuf_list(req, &req->ctx->io_buffers_cache);
+	}
+	return cflags;
+}
+
 static void __user *io_provided_buffer_select(struct io_kiocb *req, size_t *len,
 					      struct io_buffer_list *bl)
 {
io_uring/kbuf.h +6 -32
index 80b6df2c7535..5da3d4039aed 100644
@@ -47,6 +47,8 @@ int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags);
 int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
 int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg);
 
+unsigned int __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags);
+
 static inline bool io_do_buffer_select(struct io_kiocb *req)
 {
 	if (!(req->flags & REQ_F_BUFFER_SELECT))

@@ -70,7 +72,8 @@ static inline void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
 	__io_kbuf_recycle(req, issue_flags);
 }
 
-static unsigned int __io_put_kbuf(struct io_kiocb *req, struct list_head *list)
+static inline unsigned int __io_put_kbuf_list(struct io_kiocb *req,
+					      struct list_head *list)
 {
 	if (req->flags & REQ_F_BUFFER_RING) {
 		if (req->buf_list)

@@ -90,44 +93,15 @@ static inline unsigned int io_put_kbuf_comp(struct io_kiocb *req)
 
 	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
 		return 0;
-	return __io_put_kbuf(req, &req->ctx->io_buffers_comp);
+	return __io_put_kbuf_list(req, &req->ctx->io_buffers_comp);
 }
 
 static inline unsigned int io_put_kbuf(struct io_kiocb *req,
 				       unsigned issue_flags)
 {
-	unsigned int cflags;
 
 	if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)))
 		return 0;
-
-	/*
-	 * We can add this buffer back to two lists:
-	 *
-	 * 1) The io_buffers_cache list. This one is protected by the
-	 *    ctx->uring_lock. If we already hold this lock, add back to this
-	 *    list as we can grab it from issue as well.
-	 * 2) The io_buffers_comp list. This one is protected by the
-	 *    ctx->completion_lock.
-	 *
-	 * We migrate buffers from the comp_list to the issue cache list
-	 * when we need one.
-	 */
-	if (req->flags & REQ_F_BUFFER_RING) {
-		/* no buffers to recycle for this case */
-		cflags = __io_put_kbuf(req, NULL);
-	} else if (issue_flags & IO_URING_F_UNLOCKED) {
-		struct io_ring_ctx *ctx = req->ctx;
-
-		spin_lock(&ctx->completion_lock);
-		cflags = __io_put_kbuf(req, &ctx->io_buffers_comp);
-		spin_unlock(&ctx->completion_lock);
-	} else {
-		lockdep_assert_held(&req->ctx->uring_lock);
-
-		cflags = __io_put_kbuf(req, &req->ctx->io_buffers_cache);
-	}
-
-	return cflags;
+	return __io_put_kbuf(req, issue_flags);
 }
 #endif
Signature · 1 line
2.36.1
author
#16 lore raw

PATCH 13/25 io_uring: remove check_cq checking from hot paths

In reply to Pavel Begunkov

All ctx->check_cq events are slow path, don't test every single flag one by one in the hot path, but add a common guarding if.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)
io_uring/io_uring.c +19 -15
index f3cae98471b8..bd2aab895e29 100644
@@ -1807,24 +1807,25 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
 	int ret = 0;
 	unsigned long check_cq;
 
+	check_cq = READ_ONCE(ctx->check_cq);
+	if (unlikely(check_cq)) {
+		if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
+			__io_cqring_overflow_flush(ctx, false);
+		/*
+		 * Similarly do not spin if we have not informed the user of any
+		 * dropped CQE.
+		 */
+		if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT))
+			return -EBADR;
+	}
 	/*
 	 * Don't enter poll loop if we already have events pending.
 	 * If we do, we can potentially be spinning for commands that
 	 * already triggered a CQE (eg in error).
 	 */
-	check_cq = READ_ONCE(ctx->check_cq);
-	if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
-		__io_cqring_overflow_flush(ctx, false);
 	if (io_cqring_events(ctx))
 		return 0;
 
-	/*
-	 * Similarly do not spin if we have not informed the user of any
-	 * dropped CQE.
-	 */
-	if (unlikely(check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT)))
-		return -EBADR;
-
 	do {
 		/*
 		 * If a submit got punted to a workqueue, we can have the

@@ -2752,12 +2753,15 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
 	ret = io_run_task_work_sig();
 	if (ret || io_should_wake(iowq))
 		return ret;
+
 	check_cq = READ_ONCE(ctx->check_cq);
-	/* let the caller flush overflows, retry */
-	if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
-		return 1;
-	if (unlikely(check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT)))
-		return -EBADR;
+	if (unlikely(check_cq)) {
+		/* let the caller flush overflows, retry */
+		if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
+			return 1;
+		if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT))
+			return -EBADR;
+	}
 	if (!schedule_hrtimeout(&timeout, HRTIMER_MODE_ABS))
 		return -ETIME;
 	return 1;
Signature · 1 line
2.36.1
author
#17 lore raw

PATCH 14/25 io_uring: poll: remove unnecessary req->ref set

In reply to Pavel Begunkov

From: Hao Xu <[email protected]>

We now don't need to set req->refcount for poll requests since the reworked poll code ensures no request release race.

Signed-off-by Hao Xu <[email protected]>
Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/poll.c | 1 -
 1 file changed, 1 deletion(-)
io_uring/poll.c +0 -1
index b46973140ffd..be3dd77fa21c 100644
@@ -683,7 +683,6 @@ int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	if ((flags & IORING_POLL_ADD_MULTI) && (req->flags & REQ_F_CQE_SKIP))
 		return -EINVAL;
 
-	io_req_set_refcount(req);
 	req->apoll_events = poll->events = io_poll_parse_events(sqe, flags);
 	return 0;
 }
Signature · 1 line
2.36.1
author
#18 lore raw

PATCH 15/25 io_uring: switch cancel_hash to use per entry spinlock

In reply to Pavel Begunkov

From: Hao Xu <[email protected]>

Add a new io_hash_bucket structure so that each bucket in cancel_hash has separate spinlock. Use per entry lock for cancel_hash, this removes some completion lock invocation and remove contension between different cancel_hash entries.

Signed-off-by Hao Xu <[email protected]>
Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/cancel.c         | 14 ++++++-
 io_uring/cancel.h         |  6 +++
 io_uring/fdinfo.c         |  9 +++--
 io_uring/io_uring.c       |  8 ++--
 io_uring/io_uring_types.h |  2 +-
 io_uring/poll.c           | 80 ++++++++++++++++++++++++---------------
 6 files changed, 79 insertions(+), 40 deletions(-)
io_uring/cancel.c +12 -2
index 2e72231882b7..54a5e0a86b61 100644
@@ -93,14 +93,14 @@ int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd)
 	if (!ret)
 		return 0;
 
-	spin_lock(&ctx->completion_lock);
 	ret = io_poll_cancel(ctx, cd);
 	if (ret != -ENOENT)
 		goto out;
+	spin_lock(&ctx->completion_lock);
 	if (!(cd->flags & IORING_ASYNC_CANCEL_FD))
 		ret = io_timeout_cancel(ctx, cd);
-out:
 	spin_unlock(&ctx->completion_lock);
+out:
 	return ret;
 }
 

@@ -192,3 +192,13 @@ int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
 	io_req_set_res(req, ret, 0);
 	return IOU_OK;
 }
+
+void init_hash_table(struct io_hash_bucket *hash_table, unsigned size)
+{
+	unsigned int i;
+
+	for (i = 0; i < size; i++) {
+		spin_lock_init(&hash_table[i].lock);
+		INIT_HLIST_HEAD(&hash_table[i].list);
+	}
+}
io_uring/cancel.h +6 -0
index 4f35d8696325..556a7dcf160e 100644
@@ -4,3 +4,9 @@ int io_async_cancel_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags);
 
 int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd);
+void init_hash_table(struct io_hash_bucket *hash_table, unsigned size);
+
+struct io_hash_bucket {
+	spinlock_t		lock;
+	struct hlist_head	list;
+} ____cacheline_aligned_in_smp;
io_uring/fdinfo.c +6 -3
index fcedde4b4b1e..f941c73f5502 100644
@@ -13,6 +13,7 @@
 #include "io_uring.h"
 #include "sqpoll.h"
 #include "fdinfo.h"
+#include "cancel.h"
 
 #ifdef CONFIG_PROC_FS
 static __cold int io_uring_show_cred(struct seq_file *m, unsigned int id,

@@ -157,17 +158,19 @@ static __cold void __io_uring_show_fdinfo(struct io_ring_ctx *ctx,
 		mutex_unlock(&ctx->uring_lock);
 
 	seq_puts(m, "PollList:\n");
-	spin_lock(&ctx->completion_lock);
 	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
-		struct hlist_head *list = &ctx->cancel_hash[i];
+		struct io_hash_bucket *hb = &ctx->cancel_hash[i];
 		struct io_kiocb *req;
 
-		hlist_for_each_entry(req, list, hash_node)
+		spin_lock(&hb->lock);
+		hlist_for_each_entry(req, &hb->list, hash_node)
 			seq_printf(m, "  op=%d, task_works=%d\n", req->opcode,
 					task_work_pending(req->task));
+		spin_unlock(&hb->lock);
 	}
 
 	seq_puts(m, "CqOverflowList:\n");
+	spin_lock(&ctx->completion_lock);
 	list_for_each_entry(ocqe, &ctx->cq_overflow_list, list) {
 		struct io_uring_cqe *cqe = &ocqe->cqe;
io_uring/io_uring.c +5 -3
index bd2aab895e29..4e0f60ffc975 100644
@@ -717,11 +717,13 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	if (hash_bits <= 0)
 		hash_bits = 1;
 	ctx->cancel_hash_bits = hash_bits;
-	ctx->cancel_hash = kmalloc((1U << hash_bits) * sizeof(struct hlist_head),
-					GFP_KERNEL);
+	ctx->cancel_hash =
+		kmalloc((1U << hash_bits) * sizeof(struct io_hash_bucket),
+			GFP_KERNEL);
 	if (!ctx->cancel_hash)
 		goto err;
-	__hash_init(ctx->cancel_hash, 1U << hash_bits);
+
+	init_hash_table(ctx->cancel_hash, 1U << hash_bits);
 
 	ctx->dummy_ubuf = kzalloc(sizeof(*ctx->dummy_ubuf), GFP_KERNEL);
 	if (!ctx->dummy_ubuf)
io_uring/io_uring_types.h +1 -1
index 3cf06f4a4d2e..0dd3ab7eec4c 100644
@@ -222,7 +222,7 @@ struct io_ring_ctx {
 		 * manipulate the list, hence no extra locking is needed there.
 		 */
 		struct io_wq_work_list	iopoll_list;
-		struct hlist_head	*cancel_hash;
+		struct io_hash_bucket	*cancel_hash;
 		unsigned		cancel_hash_bits;
 		bool			poll_multi_queue;
io_uring/poll.c +49 -31

198 lines not on this page · raw message

Signature · 1 line
2.36.1
author
#19 lore raw

PATCH 16/25 io_uring: pass poll_find lock back

In reply to Pavel Begunkov

Instead of using implicit knowledge of what is locked or not after io_poll_find() and co returns, pass back a pointer to the locked bucket if any. If set the user must to unlock the spinlock.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/poll.c | 46 ++++++++++++++++++++++++++--------------------
 1 file changed, 26 insertions(+), 20 deletions(-)
io_uring/poll.c +26 -20
index ab4be4173cf3..ad25a964d4ed 100644
@@ -559,12 +559,15 @@ __cold bool io_poll_remove_all(struct io_ring_ctx *ctx, struct task_struct *tsk,
 }
 
 static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only,
-				     struct io_cancel_data *cd)
+				     struct io_cancel_data *cd,
+				     struct io_hash_bucket **out_bucket)
 {
 	struct io_kiocb *req;
 	u32 index = hash_long(cd->data, ctx->cancel_hash_bits);
 	struct io_hash_bucket *hb = &ctx->cancel_hash[index];
 
+	*out_bucket = NULL;
+
 	spin_lock(&hb->lock);
 	hlist_for_each_entry(req, &hb->list, hash_node) {
 		if (cd->data != req->cqe.user_data)

@@ -576,6 +579,7 @@ static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only,
 				continue;
 			req->cancel_seq = cd->seq;
 		}
+		*out_bucket = hb;
 		return req;
 	}
 	spin_unlock(&hb->lock);

@@ -583,11 +587,14 @@ static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only,
 }
 
 static struct io_kiocb *io_poll_file_find(struct io_ring_ctx *ctx,
-					  struct io_cancel_data *cd)
+					  struct io_cancel_data *cd,
+					  struct io_hash_bucket **out_bucket)
 {
 	struct io_kiocb *req;
 	int i;
 
+	*out_bucket = NULL;
+
 	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
 		struct io_hash_bucket *hb = &ctx->cancel_hash[i];
 

@@ -599,6 +606,7 @@ static struct io_kiocb *io_poll_file_find(struct io_ring_ctx *ctx,
 			if (cd->seq == req->cancel_seq)
 				continue;
 			req->cancel_seq = cd->seq;
+			*out_bucket = hb;
 			return req;
 		}
 		spin_unlock(&hb->lock);

@@ -617,23 +625,19 @@ static bool io_poll_disarm(struct io_kiocb *req)
 
 int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd)
 {
+	struct io_hash_bucket *bucket;
 	struct io_kiocb *req;
-	u32 index;
-	spinlock_t *lock;
 
 	if (cd->flags & (IORING_ASYNC_CANCEL_FD|IORING_ASYNC_CANCEL_ANY))
-		req = io_poll_file_find(ctx, cd);
+		req = io_poll_file_find(ctx, cd, &bucket);
 	else
-		req = io_poll_find(ctx, false, cd);
-	if (!req) {
-		return -ENOENT;
-	} else {
-		index = hash_long(req->cqe.user_data, ctx->cancel_hash_bits);
-		lock = &ctx->cancel_hash[index].lock;
-	}
-	io_poll_cancel_req(req);
-	spin_unlock(lock);
-	return 0;
+		req = io_poll_find(ctx, false, cd, &bucket);
+
+	if (req)
+		io_poll_cancel_req(req);
+	if (bucket)
+		spin_unlock(&bucket->lock);
+	return req ? 0 : -ENOENT;
 }
 
 static __poll_t io_poll_parse_events(const struct io_uring_sqe *sqe,

@@ -726,19 +730,21 @@ int io_poll_remove(struct io_kiocb *req, unsigned int issue_flags)
 	struct io_poll_update *poll_update = io_kiocb_to_cmd(req);
 	struct io_cancel_data cd = { .data = poll_update->old_user_data, };
 	struct io_ring_ctx *ctx = req->ctx;
-	u32 index = hash_long(cd.data, ctx->cancel_hash_bits);
-	spinlock_t *lock = &ctx->cancel_hash[index].lock;
+	struct io_hash_bucket *bucket;
 	struct io_kiocb *preq;
 	int ret2, ret = 0;
 	bool locked;
 
-	preq = io_poll_find(ctx, true, &cd);
+	preq = io_poll_find(ctx, true, &cd, &bucket);
+	if (preq)
+		ret2 = io_poll_disarm(preq);
+	if (bucket)
+		spin_unlock(&bucket->lock);
+
 	if (!preq) {
 		ret = -ENOENT;
 		goto out;
 	}
-	ret2 = io_poll_disarm(preq);
-	spin_unlock(lock);
 	if (!ret2) {
 		ret = -EALREADY;
 		goto out;
Signature · 1 line
2.36.1
author
#20 lore raw

PATCH 17/25 io_uring: clean up io_try_cancel

In reply to Pavel Begunkov

Get rid of an unnecessary extra goto in io_try_cancel() and simplify the function.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/cancel.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
io_uring/cancel.c +2 -2
index 54a5e0a86b61..2f157aebd3a0 100644
@@ -95,12 +95,12 @@ int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd)
 
 	ret = io_poll_cancel(ctx, cd);
 	if (ret != -ENOENT)
-		goto out;
+		return ret;
+
 	spin_lock(&ctx->completion_lock);
 	if (!(cd->flags & IORING_ASYNC_CANCEL_FD))
 		ret = io_timeout_cancel(ctx, cd);
 	spin_unlock(&ctx->completion_lock);
-out:
 	return ret;
 }
Signature · 1 line
2.36.1
author
#21 lore raw

PATCH 18/25 io_uring: limit number hash buckets

In reply to Pavel Begunkov

Don't allocate to many hash/cancellation buckets, there might be too many, clamp it to 8 bits, or 256 * 64B = 16KB. We don't usually have too many requests, and 256 buckets should be enough, especially since we do hash search only in the cancellation path.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
io_uring/io_uring.c +5 -5
index 4e0f60ffc975..a203943f3d71 100644
@@ -710,12 +710,12 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 
 	/*
 	 * Use 5 bits less than the max cq entries, that should give us around
-	 * 32 entries per hash list if totally full and uniformly spread.
+	 * 32 entries per hash list if totally full and uniformly spread, but
+	 * don't keep too many buckets to not overconsume memory.
 	 */
-	hash_bits = ilog2(p->cq_entries);
-	hash_bits -= 5;
-	if (hash_bits <= 0)
-		hash_bits = 1;
+	hash_bits = ilog2(p->cq_entries) - 5;
+	hash_bits = clamp(hash_bits, 1, 8);
+
 	ctx->cancel_hash_bits = hash_bits;
 	ctx->cancel_hash =
 		kmalloc((1U << hash_bits) * sizeof(struct io_hash_bucket),
Signature · 1 line
2.36.1
author
#22 lore raw

PATCH 19/25 io_uring: clean up io_ring_ctx_alloc

In reply to Pavel Begunkov

Add a variable for the number of hash buckets in io_ring_ctx_alloc(), makes it more readable.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
io_uring/io_uring.c +6 -4
index a203943f3d71..89696efcead4 100644
@@ -700,6 +700,8 @@ static __cold void io_fallback_req_func(struct work_struct *work)
 static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 {
 	struct io_ring_ctx *ctx;
+	unsigned hash_buckets;
+	size_t hash_size;
 	int hash_bits;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);

@@ -715,15 +717,15 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	 */
 	hash_bits = ilog2(p->cq_entries) - 5;
 	hash_bits = clamp(hash_bits, 1, 8);
+	hash_buckets = 1U << hash_bits;
+	hash_size = hash_buckets * sizeof(struct io_hash_bucket);
 
 	ctx->cancel_hash_bits = hash_bits;
-	ctx->cancel_hash =
-		kmalloc((1U << hash_bits) * sizeof(struct io_hash_bucket),
-			GFP_KERNEL);
+	ctx->cancel_hash = kmalloc(hash_size, GFP_KERNEL);
 	if (!ctx->cancel_hash)
 		goto err;
 
-	init_hash_table(ctx->cancel_hash, 1U << hash_bits);
+	init_hash_table(ctx->cancel_hash, hash_buckets);
 
 	ctx->dummy_ubuf = kzalloc(sizeof(*ctx->dummy_ubuf), GFP_KERNEL);
 	if (!ctx->dummy_ubuf)
Signature · 1 line
2.36.1
author
#23 lore raw

PATCH 20/25 io_uring: use state completion infra for poll reqs

In reply to Pavel Begunkov

Use io_req_task_complete() for poll request completions, so it can utilise state completions and save lots of unnecessary locking.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/poll.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)
io_uring/poll.c +2 -6
index ad25a964d4ed..2688201e872a 100644
@@ -234,12 +234,8 @@ static void io_poll_task_func(struct io_kiocb *req, bool *locked)
 
 	io_poll_remove_entries(req);
 	io_poll_req_delete(req, ctx);
-	spin_lock(&ctx->completion_lock);
-	req->cqe.flags = 0;
-	__io_req_complete_post(req);
-	io_commit_cqring(ctx);
-	spin_unlock(&ctx->completion_lock);
-	io_cqring_ev_posted(ctx);
+	io_req_set_res(req, req->cqe.res, 0);
+	io_req_task_complete(req, locked);
 }
 
 static void io_apoll_task_func(struct io_kiocb *req, bool *locked)
Signature · 1 line
2.36.1
author
#24 lore raw

PATCH 21/25 io_uring: add IORING_SETUP_SINGLE_ISSUER

In reply to Pavel Begunkov

Add a new IORING_SETUP_SINGLE_ISSUER flag and the userspace visible part of it, i.e. put limitations of submitters. Also, don't allow it together with IOPOLL as we're not going to put it to good use.

Signed-off-by Pavel Begunkov <[email protected]>
---
 include/uapi/linux/io_uring.h |  5 ++++-
 io_uring/io_uring.c           |  9 ++++++---
 io_uring/io_uring_types.h     |  1 +
 io_uring/tctx.c               | 25 +++++++++++++++++++++++--
 io_uring/tctx.h               |  4 ++--
 5 files changed, 36 insertions(+), 8 deletions(-)
include/uapi/linux/io_uring.h +4 -1
index a41ddb8c5e1f..a3a691340d3e 100644
@@ -138,9 +138,12 @@ enum {
  * IORING_SQ_TASKRUN in the sq ring flags. Not valid with COOP_TASKRUN.
  */
 #define IORING_SETUP_TASKRUN_FLAG	(1U << 9)
-
 #define IORING_SETUP_SQE128		(1U << 10) /* SQEs are 128 byte */
 #define IORING_SETUP_CQE32		(1U << 11) /* CQEs are 32 byte */
+/*
+ * Only one task is allowed to submit requests
+ */
+#define IORING_SETUP_SINGLE_ISSUER	(1U << 12)
 
 enum io_uring_op {
 	IORING_OP_NOP,
io_uring/io_uring.c +6 -3
index 89696efcead4..af0bd74e78fa 100644
@@ -3020,6 +3020,8 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
 	io_destroy_buffers(ctx);
 	if (ctx->sq_creds)
 		put_cred(ctx->sq_creds);
+	if (ctx->submitter_task)
+		put_task_struct(ctx->submitter_task);
 
 	/* there are no registered resources left, nobody uses it */
 	if (ctx->rsrc_node)

@@ -3615,7 +3617,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 		}
 		ret = to_submit;
 	} else if (to_submit) {
-		ret = io_uring_add_tctx_node(ctx);
+		ret = __io_uring_add_tctx_node(ctx, false);
 		if (unlikely(ret))
 			goto out;
 

@@ -3752,7 +3754,7 @@ static int io_uring_install_fd(struct io_ring_ctx *ctx, struct file *file)
 	if (fd < 0)
 		return fd;
 
-	ret = io_uring_add_tctx_node(ctx);
+	ret = __io_uring_add_tctx_node(ctx, false);
 	if (ret) {
 		put_unused_fd(fd);
 		return ret;

@@ -3972,7 +3974,8 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
 			IORING_SETUP_CLAMP | IORING_SETUP_ATTACH_WQ |
 			IORING_SETUP_R_DISABLED | IORING_SETUP_SUBMIT_ALL |
 			IORING_SETUP_COOP_TASKRUN | IORING_SETUP_TASKRUN_FLAG |
-			IORING_SETUP_SQE128 | IORING_SETUP_CQE32))
+			IORING_SETUP_SQE128 | IORING_SETUP_CQE32 |
+			IORING_SETUP_SINGLE_ISSUER))
 		return -EINVAL;
 
 	return io_uring_create(entries, &p, params);
io_uring/io_uring_types.h +1 -0
index 0dd3ab7eec4c..faa1477bd754 100644
@@ -241,6 +241,7 @@ struct io_ring_ctx {
 	/* Keep this last, we don't need it for the fast path */
 
 	struct io_restriction		restrictions;
+	struct task_struct		*submitter_task;
 
 	/* slow path rsrc auxilary data, used by update/register */
 	struct io_rsrc_node		*rsrc_backup_node;
io_uring/tctx.c +23 -2
index 6adf659687f8..e3138a36cf39 100644
@@ -81,12 +81,32 @@ __cold int io_uring_alloc_task_context(struct task_struct *task,
 	return 0;
 }
 
-int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)
+static int io_register_submitter(struct io_ring_ctx *ctx)
+{
+	int ret = 0;
+
+	mutex_lock(&ctx->uring_lock);
+	if (!ctx->submitter_task)
+		ctx->submitter_task = get_task_struct(current);
+	else if (ctx->submitter_task != current)
+		ret = -EEXIST;
+	mutex_unlock(&ctx->uring_lock);
+
+	return ret;
+}
+
+int __io_uring_add_tctx_node(struct io_ring_ctx *ctx, bool submitter)
 {
 	struct io_uring_task *tctx = current->io_uring;
 	struct io_tctx_node *node;
 	int ret;
 
+	if ((ctx->flags & IORING_SETUP_SINGLE_ISSUER) && submitter) {
+		ret = io_register_submitter(ctx);
+		if (ret)
+			return ret;
+	}
+
 	if (unlikely(!tctx)) {
 		ret = io_uring_alloc_task_context(current, ctx);
 		if (unlikely(ret))

@@ -120,7 +140,8 @@ int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)
 		list_add(&node->ctx_node, &ctx->tctx_list);
 		mutex_unlock(&ctx->uring_lock);
 	}
-	tctx->last = ctx;
+	if (submitter)
+		tctx->last = ctx;
 	return 0;
 }
io_uring/tctx.h +2 -2
index 7684713e950f..dde82ce4d8e2 100644
@@ -34,7 +34,7 @@ struct io_tctx_node {
 int io_uring_alloc_task_context(struct task_struct *task,
 				struct io_ring_ctx *ctx);
 void io_uring_del_tctx_node(unsigned long index);
-int __io_uring_add_tctx_node(struct io_ring_ctx *ctx);
+int __io_uring_add_tctx_node(struct io_ring_ctx *ctx, bool submitter);
 void io_uring_clean_tctx(struct io_uring_task *tctx);
 
 void io_uring_unreg_ringfd(void);

@@ -52,5 +52,5 @@ static inline int io_uring_add_tctx_node(struct io_ring_ctx *ctx)
 
 	if (likely(tctx && tctx->last == ctx))
 		return 0;
-	return __io_uring_add_tctx_node(ctx);
+	return __io_uring_add_tctx_node(ctx, true);
 }
Signature · 1 line
2.36.1
author
#25 lore raw

Re: [PATCH for-next 21/25] io_uring: add IORING_SETUP_SINGLE_ISSUER

Quoted 3 lines · Pavel Begunkov

Add a new IORING_SETUP_SINGLE_ISSUER flag and the userspace visible part of it, i.e. put limitations of submitters. Also, don't allow it together with IOPOLL as we're not going to put it to good use.

Something goes wrong after rebase, need to change this one and will send out my tests for it later.

Quoted 148 lines
Signed-off-by Pavel Begunkov <[email protected]>
---
  include/uapi/linux/io_uring.h |  5 ++++-
  io_uring/io_uring.c           |  9 ++++++---
  io_uring/io_uring_types.h     |  1 +
  io_uring/tctx.c               | 25 +++++++++++++++++++++++--
  io_uring/tctx.h               |  4 ++--
  5 files changed, 36 insertions(+), 8 deletions(-)
include/uapi/linux/io_uring.h +4 -1
index a41ddb8c5e1f..a3a691340d3e 100644
@@ -138,9 +138,12 @@ enum {
   * IORING_SQ_TASKRUN in the sq ring flags. Not valid with COOP_TASKRUN.
   */
  #define IORING_SETUP_TASKRUN_FLAG	(1U << 9)
-
  #define IORING_SETUP_SQE128		(1U << 10) /* SQEs are 128 byte */
  #define IORING_SETUP_CQE32		(1U << 11) /* CQEs are 32 byte */
+/*
+ * Only one task is allowed to submit requests
+ */
+#define IORING_SETUP_SINGLE_ISSUER	(1U << 12)
 
  enum io_uring_op {
  	IORING_OP_NOP,
io_uring/io_uring.c +6 -3
index 89696efcead4..af0bd74e78fa 100644
@@ -3020,6 +3020,8 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
  	io_destroy_buffers(ctx);
  	if (ctx->sq_creds)
  		put_cred(ctx->sq_creds);
+	if (ctx->submitter_task)
+		put_task_struct(ctx->submitter_task);
 
  	/* there are no registered resources left, nobody uses it */
  	if (ctx->rsrc_node)

@@ -3615,7 +3617,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
  		}
  		ret = to_submit;
  	} else if (to_submit) {
-		ret = io_uring_add_tctx_node(ctx);
+		ret = __io_uring_add_tctx_node(ctx, false);
  		if (unlikely(ret))
  			goto out;
 

@@ -3752,7 +3754,7 @@ static int io_uring_install_fd(struct io_ring_ctx *ctx, struct file *file)
  	if (fd < 0)
  		return fd;
 
-	ret = io_uring_add_tctx_node(ctx);
+	ret = __io_uring_add_tctx_node(ctx, false);
  	if (ret) {
  		put_unused_fd(fd);
  		return ret;

@@ -3972,7 +3974,8 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
  			IORING_SETUP_CLAMP | IORING_SETUP_ATTACH_WQ |
  			IORING_SETUP_R_DISABLED | IORING_SETUP_SUBMIT_ALL |
  			IORING_SETUP_COOP_TASKRUN | IORING_SETUP_TASKRUN_FLAG |
-			IORING_SETUP_SQE128 | IORING_SETUP_CQE32))
+			IORING_SETUP_SQE128 | IORING_SETUP_CQE32 |
+			IORING_SETUP_SINGLE_ISSUER))
  		return -EINVAL;
 
  	return io_uring_create(entries, &p, params);
io_uring/io_uring_types.h +1 -0
index 0dd3ab7eec4c..faa1477bd754 100644
@@ -241,6 +241,7 @@ struct io_ring_ctx {
  	/* Keep this last, we don't need it for the fast path */
 
  	struct io_restriction		restrictions;
+	struct task_struct		*submitter_task;
 
  	/* slow path rsrc auxilary data, used by update/register */
  	struct io_rsrc_node		*rsrc_backup_node;
io_uring/tctx.c +23 -2
index 6adf659687f8..e3138a36cf39 100644
@@ -81,12 +81,32 @@ __cold int io_uring_alloc_task_context(struct task_struct *task,
  	return 0;
  }
 
-int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)
+static int io_register_submitter(struct io_ring_ctx *ctx)
+{
+	int ret = 0;
+
+	mutex_lock(&ctx->uring_lock);
+	if (!ctx->submitter_task)
+		ctx->submitter_task = get_task_struct(current);
+	else if (ctx->submitter_task != current)
+		ret = -EEXIST;
+	mutex_unlock(&ctx->uring_lock);
+
+	return ret;
+}
+
+int __io_uring_add_tctx_node(struct io_ring_ctx *ctx, bool submitter)
  {
  	struct io_uring_task *tctx = current->io_uring;
  	struct io_tctx_node *node;
  	int ret;
 
+	if ((ctx->flags & IORING_SETUP_SINGLE_ISSUER) && submitter) {
+		ret = io_register_submitter(ctx);
+		if (ret)
+			return ret;
+	}
+
  	if (unlikely(!tctx)) {
  		ret = io_uring_alloc_task_context(current, ctx);
  		if (unlikely(ret))

@@ -120,7 +140,8 @@ int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)
  		list_add(&node->ctx_node, &ctx->tctx_list);
  		mutex_unlock(&ctx->uring_lock);
  	}
-	tctx->last = ctx;
+	if (submitter)
+		tctx->last = ctx;
  	return 0;
  }
io_uring/tctx.h +2 -2
index 7684713e950f..dde82ce4d8e2 100644
@@ -34,7 +34,7 @@ struct io_tctx_node {
  int io_uring_alloc_task_context(struct task_struct *task,
  				struct io_ring_ctx *ctx);
  void io_uring_del_tctx_node(unsigned long index);
-int __io_uring_add_tctx_node(struct io_ring_ctx *ctx);
+int __io_uring_add_tctx_node(struct io_ring_ctx *ctx, bool submitter);
  void io_uring_clean_tctx(struct io_uring_task *tctx);
 
  void io_uring_unreg_ringfd(void);

@@ -52,5 +52,5 @@ static inline int io_uring_add_tctx_node(struct io_ring_ctx *ctx)
 
  	if (likely(tctx && tctx->last == ctx))
  		return 0;
-	return __io_uring_add_tctx_node(ctx);
+	return __io_uring_add_tctx_node(ctx, true);
  }
Signature · 1 line
Pavel Begunkov
author
#26 lore raw

PATCH 22/25 io_uring: pass hash table into poll_find

In reply to Pavel Begunkov

In preparation for having multiple cancellation hash tables, pass a table pointer into io_poll_find() and other poll cancel functions.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/poll.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)
io_uring/poll.c +14 -6
index 2688201e872a..b57e39082bac 100644
@@ -556,11 +556,12 @@ __cold bool io_poll_remove_all(struct io_ring_ctx *ctx, struct task_struct *tsk,
 
 static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only,
 				     struct io_cancel_data *cd,
+				     struct io_hash_bucket hash_table[],
 				     struct io_hash_bucket **out_bucket)
 {
 	struct io_kiocb *req;
 	u32 index = hash_long(cd->data, ctx->cancel_hash_bits);
-	struct io_hash_bucket *hb = &ctx->cancel_hash[index];
+	struct io_hash_bucket *hb = &hash_table[index];
 
 	*out_bucket = NULL;
 

@@ -584,6 +585,7 @@ static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only,
 
 static struct io_kiocb *io_poll_file_find(struct io_ring_ctx *ctx,
 					  struct io_cancel_data *cd,
+					  struct io_hash_bucket hash_table[],
 					  struct io_hash_bucket **out_bucket)
 {
 	struct io_kiocb *req;

@@ -592,7 +594,7 @@ static struct io_kiocb *io_poll_file_find(struct io_ring_ctx *ctx,
 	*out_bucket = NULL;
 
 	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
-		struct io_hash_bucket *hb = &ctx->cancel_hash[i];
+		struct io_hash_bucket *hb = &hash_table[i];
 
 		spin_lock(&hb->lock);
 		hlist_for_each_entry(req, &hb->list, hash_node) {

@@ -619,15 +621,16 @@ static bool io_poll_disarm(struct io_kiocb *req)
 	return true;
 }
 
-int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd)
+static int __io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
+			    struct io_hash_bucket hash_table[])
 {
 	struct io_hash_bucket *bucket;
 	struct io_kiocb *req;
 
 	if (cd->flags & (IORING_ASYNC_CANCEL_FD|IORING_ASYNC_CANCEL_ANY))
-		req = io_poll_file_find(ctx, cd, &bucket);
+		req = io_poll_file_find(ctx, cd, ctx->cancel_hash, &bucket);
 	else
-		req = io_poll_find(ctx, false, cd, &bucket);
+		req = io_poll_find(ctx, false, cd, ctx->cancel_hash, &bucket);
 
 	if (req)
 		io_poll_cancel_req(req);

@@ -636,6 +639,11 @@ int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd)
 	return req ? 0 : -ENOENT;
 }
 
+int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd)
+{
+	return __io_poll_cancel(ctx, cd, ctx->cancel_hash);
+}
+
 static __poll_t io_poll_parse_events(const struct io_uring_sqe *sqe,
 				     unsigned int flags)
 {

@@ -731,7 +739,7 @@ int io_poll_remove(struct io_kiocb *req, unsigned int issue_flags)
 	int ret2, ret = 0;
 	bool locked;
 
-	preq = io_poll_find(ctx, true, &cd, &bucket);
+	preq = io_poll_find(ctx, true, &cd, ctx->cancel_hash, &bucket);
 	if (preq)
 		ret2 = io_poll_disarm(preq);
 	if (bucket)
Signature · 1 line
2.36.1
author
#27 lore raw

PATCH 23/25 io_uring: introduce a struct for hash table

In reply to Pavel Begunkov

Instead of passing around a pointer to hash buckets, add a bit of type safety and wrap it into a structure.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/cancel.c         |  6 +++---
 io_uring/cancel.h         |  7 +------
 io_uring/fdinfo.c         |  4 ++--
 io_uring/io_uring.c       | 29 ++++++++++++++++------------
 io_uring/io_uring_types.h | 13 +++++++++++--
 io_uring/poll.c           | 40 +++++++++++++++++++++------------------
 6 files changed, 56 insertions(+), 43 deletions(-)
io_uring/cancel.c +3 -3
index 2f157aebd3a0..1ee7bacd447f 100644
@@ -193,12 +193,12 @@ int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
 	return IOU_OK;
 }
 
-void init_hash_table(struct io_hash_bucket *hash_table, unsigned size)
+void init_hash_table(struct io_hash_table *table, unsigned size)
 {
 	unsigned int i;
 
 	for (i = 0; i < size; i++) {
-		spin_lock_init(&hash_table[i].lock);
-		INIT_HLIST_HEAD(&hash_table[i].list);
+		spin_lock_init(&table->hbs[i].lock);
+		INIT_HLIST_HEAD(&table->hbs[i].list);
 	}
 }
io_uring/cancel.h +1 -6
index 556a7dcf160e..fd4cb1a2595d 100644
@@ -4,9 +4,4 @@ int io_async_cancel_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags);
 
 int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd);
-void init_hash_table(struct io_hash_bucket *hash_table, unsigned size);
-
-struct io_hash_bucket {
-	spinlock_t		lock;
-	struct hlist_head	list;
-} ____cacheline_aligned_in_smp;
+void init_hash_table(struct io_hash_table *table, unsigned size);
io_uring/fdinfo.c +2 -2
index f941c73f5502..344e7d90d557 100644
@@ -158,8 +158,8 @@ static __cold void __io_uring_show_fdinfo(struct io_ring_ctx *ctx,
 		mutex_unlock(&ctx->uring_lock);
 
 	seq_puts(m, "PollList:\n");
-	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
-		struct io_hash_bucket *hb = &ctx->cancel_hash[i];
+	for (i = 0; i < (1U << ctx->cancel_table.hash_bits); i++) {
+		struct io_hash_bucket *hb = &ctx->cancel_table.hbs[i];
 		struct io_kiocb *req;
 
 		spin_lock(&hb->lock);
io_uring/io_uring.c +17 -12
index af0bd74e78fa..64a945fe47f5 100644
@@ -697,11 +697,23 @@ static __cold void io_fallback_req_func(struct work_struct *work)
 	percpu_ref_put(&ctx->refs);
 }
 
+static int io_alloc_hash_table(struct io_hash_table *table, unsigned bits)
+{
+	unsigned hash_buckets = 1U << bits;
+	size_t hash_size = hash_buckets * sizeof(table->hbs[0]);
+
+	table->hbs = kmalloc(hash_size, GFP_KERNEL);
+	if (!table->hbs)
+		return -ENOMEM;
+
+	table->hash_bits = bits;
+	init_hash_table(table, hash_buckets);
+	return 0;
+}
+
 static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 {
 	struct io_ring_ctx *ctx;
-	unsigned hash_buckets;
-	size_t hash_size;
 	int hash_bits;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);

@@ -717,16 +729,9 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	 */
 	hash_bits = ilog2(p->cq_entries) - 5;
 	hash_bits = clamp(hash_bits, 1, 8);
-	hash_buckets = 1U << hash_bits;
-	hash_size = hash_buckets * sizeof(struct io_hash_bucket);
-
-	ctx->cancel_hash_bits = hash_bits;
-	ctx->cancel_hash = kmalloc(hash_size, GFP_KERNEL);
-	if (!ctx->cancel_hash)
+	if (io_alloc_hash_table(&ctx->cancel_table, hash_bits))
 		goto err;
 
-	init_hash_table(ctx->cancel_hash, hash_buckets);
-
 	ctx->dummy_ubuf = kzalloc(sizeof(*ctx->dummy_ubuf), GFP_KERNEL);
 	if (!ctx->dummy_ubuf)
 		goto err;

@@ -767,7 +772,7 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	return ctx;
 err:
 	kfree(ctx->dummy_ubuf);
-	kfree(ctx->cancel_hash);
+	kfree(ctx->cancel_table.hbs);
 	kfree(ctx->io_bl);
 	xa_destroy(&ctx->io_bl_xa);
 	kfree(ctx);

@@ -3050,7 +3055,7 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
 	io_req_caches_free(ctx);
 	if (ctx->hash_map)
 		io_wq_put_hash(ctx->hash_map);
-	kfree(ctx->cancel_hash);
+	kfree(ctx->cancel_table.hbs);
 	kfree(ctx->dummy_ubuf);
 	kfree(ctx->io_bl);
 	xa_destroy(&ctx->io_bl_xa);
io_uring/io_uring_types.h +11 -2
index faa1477bd754..d1ce3735aca1 100644
@@ -7,6 +7,16 @@
 #include "io-wq.h"
 #include "filetable.h"
 
+struct io_hash_bucket {
+	spinlock_t		lock;
+	struct hlist_head	list;
+} ____cacheline_aligned_in_smp;
+
+struct io_hash_table {
+	struct io_hash_bucket	*hbs;
+	unsigned		hash_bits;
+};
+
 struct io_uring {
 	u32 head ____cacheline_aligned_in_smp;
 	u32 tail ____cacheline_aligned_in_smp;

@@ -222,8 +232,7 @@ struct io_ring_ctx {
 		 * manipulate the list, hence no extra locking is needed there.
 		 */
 		struct io_wq_work_list	iopoll_list;
-		struct io_hash_bucket	*cancel_hash;
-		unsigned		cancel_hash_bits;
+		struct io_hash_table	cancel_table;
 		bool			poll_multi_queue;
 
 		struct list_head	io_buffers_comp;
io_uring/poll.c +22 -18
index b57e39082bac..2f49d15cfcce 100644
@@ -73,9 +73,9 @@ static struct io_poll *io_poll_get_single(struct io_kiocb *req)
 
 static void io_poll_req_insert(struct io_kiocb *req)
 {
-	struct io_ring_ctx *ctx = req->ctx;
-	u32 index = hash_long(req->cqe.user_data, ctx->cancel_hash_bits);
-	struct io_hash_bucket *hb = &ctx->cancel_hash[index];
+	struct io_hash_table *table = &req->ctx->cancel_table;
+	u32 index = hash_long(req->cqe.user_data, table->hash_bits);
+	struct io_hash_bucket *hb = &table->hbs[index];
 
 	spin_lock(&hb->lock);
 	hlist_add_head(&req->hash_node, &hb->list);

@@ -84,8 +84,9 @@ static void io_poll_req_insert(struct io_kiocb *req)
 
 static void io_poll_req_delete(struct io_kiocb *req, struct io_ring_ctx *ctx)
 {
-	u32 index = hash_long(req->cqe.user_data, ctx->cancel_hash_bits);
-	spinlock_t *lock = &ctx->cancel_hash[index].lock;
+	struct io_hash_table *table = &req->ctx->cancel_table;
+	u32 index = hash_long(req->cqe.user_data, table->hash_bits);
+	spinlock_t *lock = &table->hbs[index].lock;
 
 	spin_lock(lock);
 	hash_del(&req->hash_node);

@@ -533,13 +534,15 @@ int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags)
 __cold bool io_poll_remove_all(struct io_ring_ctx *ctx, struct task_struct *tsk,
 			       bool cancel_all)
 {
+	struct io_hash_table *table = &ctx->cancel_table;
+	unsigned nr_buckets = 1U << table->hash_bits;
 	struct hlist_node *tmp;
 	struct io_kiocb *req;
 	bool found = false;
 	int i;
 
-	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
-		struct io_hash_bucket *hb = &ctx->cancel_hash[i];
+	for (i = 0; i < nr_buckets; i++) {
+		struct io_hash_bucket *hb = &table->hbs[i];
 
 		spin_lock(&hb->lock);
 		hlist_for_each_entry_safe(req, tmp, &hb->list, hash_node) {

@@ -556,12 +559,12 @@ __cold bool io_poll_remove_all(struct io_ring_ctx *ctx, struct task_struct *tsk,
 
 static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only,
 				     struct io_cancel_data *cd,
-				     struct io_hash_bucket hash_table[],
+				     struct io_hash_table *table,
 				     struct io_hash_bucket **out_bucket)
 {
 	struct io_kiocb *req;
-	u32 index = hash_long(cd->data, ctx->cancel_hash_bits);
-	struct io_hash_bucket *hb = &hash_table[index];
+	u32 index = hash_long(cd->data, table->hash_bits);
+	struct io_hash_bucket *hb = &table->hbs[index];
 
 	*out_bucket = NULL;
 

@@ -585,16 +588,17 @@ static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only,
 
 static struct io_kiocb *io_poll_file_find(struct io_ring_ctx *ctx,
 					  struct io_cancel_data *cd,
-					  struct io_hash_bucket hash_table[],
+					  struct io_hash_table *table,
 					  struct io_hash_bucket **out_bucket)
 {
+	unsigned nr_buckets = 1U << table->hash_bits;
 	struct io_kiocb *req;
 	int i;
 
 	*out_bucket = NULL;
 
-	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
-		struct io_hash_bucket *hb = &hash_table[i];
+	for (i = 0; i < nr_buckets; i++) {
+		struct io_hash_bucket *hb = &table->hbs[i];
 
 		spin_lock(&hb->lock);
 		hlist_for_each_entry(req, &hb->list, hash_node) {

@@ -622,15 +626,15 @@ static bool io_poll_disarm(struct io_kiocb *req)
 }
 
 static int __io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
-			    struct io_hash_bucket hash_table[])
+			    struct io_hash_table *table)
 {
 	struct io_hash_bucket *bucket;
 	struct io_kiocb *req;
 
 	if (cd->flags & (IORING_ASYNC_CANCEL_FD|IORING_ASYNC_CANCEL_ANY))
-		req = io_poll_file_find(ctx, cd, ctx->cancel_hash, &bucket);
+		req = io_poll_file_find(ctx, cd, table, &bucket);
 	else
-		req = io_poll_find(ctx, false, cd, ctx->cancel_hash, &bucket);
+		req = io_poll_find(ctx, false, cd, table, &bucket);
 
 	if (req)
 		io_poll_cancel_req(req);

@@ -641,7 +645,7 @@ static int __io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
 
 int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd)
 {
-	return __io_poll_cancel(ctx, cd, ctx->cancel_hash);
+	return __io_poll_cancel(ctx, cd, &ctx->cancel_table);
 }
 
 static __poll_t io_poll_parse_events(const struct io_uring_sqe *sqe,

@@ -739,7 +743,7 @@ int io_poll_remove(struct io_kiocb *req, unsigned int issue_flags)
 	int ret2, ret = 0;
 	bool locked;
 
-	preq = io_poll_find(ctx, true, &cd, ctx->cancel_hash, &bucket);
+	preq = io_poll_find(ctx, true, &cd, &ctx->cancel_table, &bucket);
 	if (preq)
 		ret2 = io_poll_disarm(preq);
 	if (bucket)
Signature · 1 line
2.36.1
author
#28 lore raw

PATCH 24/25 io_uring: propagate locking state to poll cancel

In reply to Pavel Begunkov

Poll cancellation will be soon need to grab ->uring_lock inside, pass the locking state, i.e. issue_flags, inside the cancellation functions.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/cancel.c  | 7 ++++---
 io_uring/cancel.h  | 3 ++-
 io_uring/poll.c    | 3 ++-
 io_uring/poll.h    | 3 ++-
 io_uring/timeout.c | 3 ++-
 5 files changed, 12 insertions(+), 7 deletions(-)
io_uring/cancel.c +4 -3
index 1ee7bacd447f..14fcd4fd10d9 100644
@@ -78,7 +78,8 @@ static int io_async_cancel_one(struct io_uring_task *tctx,
 	return ret;
 }
 
-int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd)
+int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd,
+		  unsigned issue_flags)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 	int ret;

@@ -93,7 +94,7 @@ int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd)
 	if (!ret)
 		return 0;
 
-	ret = io_poll_cancel(ctx, cd);
+	ret = io_poll_cancel(ctx, cd, issue_flags);
 	if (ret != -ENOENT)
 		return ret;
 

@@ -136,7 +137,7 @@ static int __io_async_cancel(struct io_cancel_data *cd, struct io_kiocb *req,
 	int ret, nr = 0;
 
 	do {
-		ret = io_try_cancel(req, cd);
+		ret = io_try_cancel(req, cd, issue_flags);
 		if (ret == -ENOENT)
 			break;
 		if (!all)
io_uring/cancel.h +2 -1
index fd4cb1a2595d..8dd259dc383e 100644
@@ -3,5 +3,6 @@
 int io_async_cancel_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags);
 
-int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd);
+int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd,
+		  unsigned int issue_flags);
 void init_hash_table(struct io_hash_table *table, unsigned size);
io_uring/poll.c +2 -1
index 2f49d15cfcce..db7357de7f8c 100644
@@ -643,7 +643,8 @@ static int __io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
 	return req ? 0 : -ENOENT;
 }
 
-int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd)
+int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
+		   unsigned issue_flags)
 {
 	return __io_poll_cancel(ctx, cd, &ctx->cancel_table);
 }
io_uring/poll.h +2 -1
index cc75c1567a84..fa3e19790281 100644
@@ -24,7 +24,8 @@ int io_poll_add(struct io_kiocb *req, unsigned int issue_flags);
 int io_poll_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 int io_poll_remove(struct io_kiocb *req, unsigned int issue_flags);
 
-int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd);
+int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
+		   unsigned issue_flags);
 int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags);
 bool io_poll_remove_all(struct io_ring_ctx *ctx, struct task_struct *tsk,
 			bool cancel_all);
io_uring/timeout.c +2 -1
index 89000aae65d9..0b3751959e88 100644
@@ -262,6 +262,7 @@ int io_timeout_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd)
 
 static void io_req_task_link_timeout(struct io_kiocb *req, bool *locked)
 {
+	unsigned issue_flags = *locked ? 0 : IO_URING_F_UNLOCKED;
 	struct io_timeout *timeout = io_kiocb_to_cmd(req);
 	struct io_kiocb *prev = timeout->prev;
 	int ret = -ENOENT;

@@ -273,7 +274,7 @@ static void io_req_task_link_timeout(struct io_kiocb *req, bool *locked)
 				.data		= prev->cqe.user_data,
 			};
 
-			ret = io_try_cancel(req, &cd);
+			ret = io_try_cancel(req, &cd, issue_flags);
 		}
 		io_req_set_res(req, ret ?: -ETIME, 0);
 		io_req_complete_post(req);
Signature · 1 line
2.36.1
author
#29 lore raw

PATCH 25/25 io_uring: mutex locked poll hashing

In reply to Pavel Begunkov

Currently we do two extra spin lock/unlock pairs to add a poll/apoll request to the cancellation hash table and remove it from there.

On the submission side we often already hold ->uring_lock and tw completion is likely to hold it as well. Add a second cancellation hash table protected by ->uring_lock. In concerns for latency because of a need to have the mutex locked on the completion side, use the new table only in following cases:

1) IORING_SETUP_SINGLE_ISSUER: only one task grabs uring_lock, so there is no contention and so the main tw hander will always end up grabbing it before calling into callbacks.

2) IORING_SETUP_SQPOLL: same as with single issuer, only one task is using ->uring_lock.

3) apoll: we normally grab the lock on the completion side anyway to execute the request, so it's free.

Signed-off-by Pavel Begunkov <[email protected]>
---
 io_uring/io_uring.c       |   9 +++-
 io_uring/io_uring_types.h |   4 ++
 io_uring/poll.c           | 111 ++++++++++++++++++++++++++++++--------
 3 files changed, 102 insertions(+), 22 deletions(-)
io_uring/io_uring.c +8 -1
index 64a945fe47f5..169947b3679e 100644
@@ -731,6 +731,8 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	hash_bits = clamp(hash_bits, 1, 8);
 	if (io_alloc_hash_table(&ctx->cancel_table, hash_bits))
 		goto err;
+	if (io_alloc_hash_table(&ctx->cancel_table_locked, hash_bits))
+		goto err;
 
 	ctx->dummy_ubuf = kzalloc(sizeof(*ctx->dummy_ubuf), GFP_KERNEL);
 	if (!ctx->dummy_ubuf)

@@ -773,6 +775,7 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 err:
 	kfree(ctx->dummy_ubuf);
 	kfree(ctx->cancel_table.hbs);
+	kfree(ctx->cancel_table_locked.hbs);
 	kfree(ctx->io_bl);
 	xa_destroy(&ctx->io_bl_xa);
 	kfree(ctx);

@@ -3056,6 +3059,7 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
 	if (ctx->hash_map)
 		io_wq_put_hash(ctx->hash_map);
 	kfree(ctx->cancel_table.hbs);
+	kfree(ctx->cancel_table_locked.hbs);
 	kfree(ctx->dummy_ubuf);
 	kfree(ctx->io_bl);
 	xa_destroy(&ctx->io_bl_xa);

@@ -3217,12 +3221,13 @@ static __cold void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
 		__io_cqring_overflow_flush(ctx, true);
 	xa_for_each(&ctx->personalities, index, creds)
 		io_unregister_personality(ctx, index);
+	if (ctx->rings)
+		io_poll_remove_all(ctx, NULL, true);
 	mutex_unlock(&ctx->uring_lock);
 
 	/* failed during ring init, it couldn't have issued any requests */
 	if (ctx->rings) {
 		io_kill_timeouts(ctx, NULL, true);
-		io_poll_remove_all(ctx, NULL, true);
 		/* if we failed setting up the ctx, we might not have any rings */
 		io_iopoll_try_reap_events(ctx);
 	}

@@ -3347,7 +3352,9 @@ static __cold void io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
 		}
 
 		ret |= io_cancel_defer_files(ctx, task, cancel_all);
+		mutex_lock(&ctx->uring_lock);
 		ret |= io_poll_remove_all(ctx, task, cancel_all);
+		mutex_unlock(&ctx->uring_lock);
 		ret |= io_kill_timeouts(ctx, task, cancel_all);
 		if (task)
 			ret |= io_run_task_work();
io_uring/io_uring_types.h +4 -0
index d1ce3735aca1..6c3c3c88223a 100644
@@ -189,6 +189,7 @@ struct io_ring_ctx {
 		struct xarray		io_bl_xa;
 		struct list_head	io_buffers_cache;
 
+		struct io_hash_table	cancel_table_locked;
 		struct list_head	cq_overflow_list;
 		struct list_head	apoll_cache;
 		struct xarray		personalities;

@@ -323,6 +324,7 @@ enum {
 	/* keep async read/write and isreg together and in order */
 	REQ_F_SUPPORT_NOWAIT_BIT,
 	REQ_F_ISREG_BIT,
+	REQ_F_HASH_LOCKED_BIT,
 
 	/* not a real bit, just to check we're not overflowing the space */
 	__REQ_F_LAST_BIT,

@@ -388,6 +390,8 @@ enum {
 	REQ_F_APOLL_MULTISHOT	= BIT(REQ_F_APOLL_MULTISHOT_BIT),
 	/* recvmsg special flag, clear EPOLLIN */
 	REQ_F_CLEAR_POLLIN	= BIT(REQ_F_CLEAR_POLLIN_BIT),
+	/* hashed into ->cancel_hash_locked */
+	REQ_F_HASH_LOCKED	= BIT(REQ_F_HASH_LOCKED_BIT),
 };
 
 typedef void (*io_req_tw_func_t)(struct io_kiocb *req, bool *locked);
io_uring/poll.c +90 -21

195 lines not on this page · raw message

Signature · 1 line
2.36.1