mpt3sas/megaraid_sas : irq poll to avoid CPU hard and soft lockups

Patch for Fix-1 explained in PATCH 0.

---
 mpt3sas/mpt3sas_base.c | 67
++++++++++++++++++++++++++++++++++++++------------
 mpt3sas/mpt3sas_base.h |  4 +++
 2 files changed, 55 insertions(+), 17 deletions(-)

08237b8..0b351d4 100644

@@ -963,17 +963,15 @@ union reply_descriptor {  };
 
 /**
- * _base_interrupt - MPT adapter (IOC) specific interrupt handler.
- * @irq: irq number (not used)
- * @bus_id: bus identifier cookie == pointer to MPT_ADAPTER structure
- * @r: pt_regs pointer (not used)
+ * mpt3sas_process_reply_queue - Process the RDs from reply descriptor
+ queue
+ * @ reply_q- reply queue
+ * @ bugget- command completion budget
  *
- * Return IRQ_HANDLE if processed, else IRQ_NONE.
+ * Returns number of RDs processed.
  */
-static irqreturn_t
-_base_interrupt(int irq, void *bus_id)
+int
+mpt3sas_process_reply_queue(struct adapter_reply_queue *reply_q, u32
+budget)
 {
-	struct adapter_reply_queue *reply_q = bus_id;
 	union reply_descriptor rd;
 	u32 completed_cmds;

u8 request_desript_type;
@@ -985,18 +983,15 @@ _base_interrupt(int irq, void *bus_id)
Mpi2ReplyDescriptorsUnion_t *rpf;
u8 rc;

- if (ioc->mask_interrupts)
- return IRQ_NONE;
-
if (!atomic_add_unless(&reply_q->busy, 1, 1))
- return IRQ_NONE;
+ return 0;

rpf = &reply_q->reply_post_free[reply_q->reply_post_host_index]; request_desript_type = rpf->Default.ReplyFlags
& MPI2_RPY_DESCRIPT_FLAGS_TYPE_MASK;
if (request_desript_type == MPI2_RPY_DESCRIPT_FLAGS_UNUSED) {
atomic_dec(&reply_q->busy);
- return IRQ_NONE;
+ return 0;
}

completed_cmds = 0;
@@ -1072,7 +1067,7 @@ _base_interrupt(int irq, void *bus_id)
* So that FW can find enough entries to post the Reply
* Descriptors in the reply descriptor post queue. */
- if (completed_cmds > ioc->hba_queue_depth/3) {
+ if (completed_cmds == budget) {
if (ioc->combined_reply_queue) {
writel(reply_q->reply_post_host_index |
((msix_index & 7) <<
@@ -1084,6 +1079,8 @@ _base_interrupt(int irq, void *bus_id)

MPI2_RPHI_MSIX_INDEX_SHIFT),

&ioc->chip->ReplyPostHostIndex);
}
+ if (ioc->irqpoll_weight)
+ break;
completed_cmds = 1;
}
if (request_desript_type ==
MPI2_RPY_DESCRIPT_FLAGS_UNUSED) @@ -1098,14 +1095,14 @@ _base_interrupt(int irq, void *bus_id)

if (!completed_cmds) {
atomic_dec(&reply_q->busy);
- return IRQ_NONE;
+ return 0;
}

if (ioc->is_warpdrive) {
writel(reply_q->reply_post_host_index, ioc->reply_post_host_index[msix_index]); atomic_dec(&reply_q->busy);
- return IRQ_HANDLED;
+ return completed_cmds;
}

/* Update Reply Post Host Index.
@@ -1132,6 +1129,27 @@ _base_interrupt(int irq, void *bus_id)
MPI2_RPHI_MSIX_INDEX_SHIFT), &ioc->chip->ReplyPostHostIndex);
atomic_dec(&reply_q->busy);
+ return completed_cmds;
+}
+
+/**
+ * _base_interrupt - MPT adapter (IOC) specific interrupt handler.
+ * @irq: irq number (not used)
+ * @bus_id: bus identifier cookie == pointer to MPT_ADAPTER structure
+ * @r: pt_regs pointer (not used)
+ *
+ * Return IRQ_HANDLE if processed, else IRQ_NONE.
+ */
+static irqreturn_t
+_base_interrupt(int irq, void *bus_id)
+{
+ struct adapter_reply_queue *reply_q = bus_id;
+ struct MPT3SAS_ADAPTER *ioc = reply_q->ioc;
+
+ if (ioc->mask_interrupts)
+ return IRQ_NONE;
+
+ irq_poll_sched(&reply_q->irqpoll);
return IRQ_HANDLED;
}

@@ -2285,6 +2303,20 @@ _base_check_enable_msix(struct MPT3SAS_ADAPTER *ioc)
return 0;
}

+int mpt3sas_irqpoll(struct irq_poll *irqpoll, int budget) {
+ struct adapter_reply_queue *reply_q;
+ int num_entries = 0;
+
+ reply_q = container_of(irqpoll, struct adapter_reply_queue,
irqpoll);
+
+ num_entries = mpt3sas_process_reply_queue(reply_q, budget);
+ if (num_entries < budget)
+ irq_poll_complete(irqpoll);
+
+ return num_entries;
+}
+
/**
* _base_free_irq - free irq
* @ioc: per adapter object
@@ -2301,6 +2333,7 @@ _base_free_irq(struct MPT3SAS_ADAPTER *ioc)

list_for_each_entry_safe(reply_q, next, &ioc->reply_queue_list,
list) {
list_del(&reply_q->list);
+ irq_poll_disable(&reply_q->irqpoll);
free_irq(pci_irq_vector(ioc->pdev, reply_q->msix_index),
reply_q);
kfree(reply_q);
@@ -2348,6 +2381,7 @@ _base_request_irq(struct MPT3SAS_ADAPTER *ioc, u8 index)

INIT_LIST_HEAD(&reply_q->list); list_add_tail(&reply_q->list, &ioc->reply_queue_list);
+ irq_poll_init(&reply_q->irqpoll, ioc->irqpoll_weight,
+mpt3sas_irqpoll);
return 0;
}

@@ -2482,6 +2516,7 @@ _base_enable_msix(struct MPT3SAS_ADAPTER *ioc)
}

ioc->msix_enable = 1;
+ ioc->irqpoll_weight = 50;
ioc->reply_queue_count = r;
for (i = 0; i < ioc->reply_queue_count; i++) {
r = _base_request_irq(ioc, i);

60f42ca..456d928 100644

@@ -66,6 +66,7 @@
 #include <scsi/scsi_eh.h>
 #include <linux/pci.h>
 #include <linux/poll.h>
+#include <linux/irq_poll.h>
 
 #include "mpt3sas_debug.h"
 #include "mpt3sas_trigger_diag.h"

@@ -846,6 +847,8 @@ struct _event_ack_list {  struct adapter_reply_queue {
 	struct MPT3SAS_ADAPTER	*ioc;
 	u8			msix_index;
+	u32			max_budget;
+	struct irq_poll		irqpoll;
 	u32			reply_post_host_index;
 	Mpi2ReplyDescriptorsUnion_t *reply_post_free;
 	char			name[MPT_NAME_LENGTH];

@@ -1353,6 +1356,7 @@ struct MPT3SAS_ADAPTER {
 	u16		device_remove_in_progress_sz;
 	u8		is_gen35_ioc;
 	u8		atomic_desc_capable;
+	u32		irqpoll_weight;
 	PUT_SMID_IO_FP_HIP put_smid_scsi_io;
 	PUT_SMID_IO_FP_HIP put_smid_fast_path;
 	PUT_SMID_IO_FP_HIP put_smid_hi_priority;

--
2.5.5

Ahm, PATCH 0 a.k.a the cover letter doesn't get merged so the git history won't have an explanation at all. Please write a proper commit message.

Thanks,
Johannes

Johannes Thumshirn                                          Storage
[email protected]                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

and

history

For now I am looking for input from linux community regarding approach used in my solution.
I will convert RFC to PATCH and most suitable header I will attach with each patch. Hope it is OK.

Current RFC has changes included for mpt3sas. Same logic will be followed for megaraid_sas as well. Just for reference I have posted changes of mpt3sas and not included megaraid_sas.