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FAILED: patch "[PATCH] bus: mhi: ep: Change state_lock to mutex" failed to apply to 6.2-stable tree

PATCH [email protected] 1 participant 1 message Mar 7, 2023

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The patch below does not apply to the 6.2-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.2.y
git checkout FETCH_HEAD
git cherry-pick -x 1ddc7618294084fff8d673217a9479550990ee84
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '[email protected]' --subject-prefix 'PATCH 6.2.y' HEAD^..

Possible dependencies:

1ddc76182940 ("bus: mhi: ep: Change state_lock to mutex") 47a1dcaea073 ("bus: mhi: ep: Power up/down MHI stack during MHI RESET")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1ddc7618294084fff8d673217a9479550990ee84 Mon Sep 17 00:00:00 2001
From: Manivannan Sadhasivam <[email protected]>
Date: Mon, 23 Jan 2023 12:59:45 +0530
Subject: [PATCH] bus: mhi: ep: Change state_lock to mutex

state_lock, the spinlock type is meant to protect race against concurrent MHI state transitions. In mhi_ep_set_m0_state(), while the state_lock is being held, the channels are resumed in mhi_ep_resume_channels() if the previous state was M3. This causes sleeping in atomic bug, since mhi_ep_resume_channels() use mutex internally.

Since the state_lock is supposed to be held throughout the state change, it is not ideal to drop the lock before calling mhi_ep_resume_channels(). So to fix this issue, let's change the type of state_lock to mutex. This would also allow holding the lock throughout all state transitions thereby avoiding any potential race.

Cc <[email protected]> # 5.19
Fixes e4b7b5f0f30a ("bus: mhi: ep: Add support for suspending and resuming channels")
Reported-by Dan Carpenter <[email protected]>
Reviewed-by Jeffrey Hugo <[email protected]>
Signed-off-by Manivannan Sadhasivam <[email protected]>
drivers/bus/mhi/ep/main.c +5 -3
index bcaaba97ef63..528c00b232bf 100644
@@ -1001,11 +1001,11 @@ static void mhi_ep_reset_worker(struct work_struct *work)
 
 	mhi_ep_power_down(mhi_cntrl);
 
-	spin_lock_bh(&mhi_cntrl->state_lock);
+	mutex_lock(&mhi_cntrl->state_lock);
+
 	/* Reset MMIO to signal host that the MHI_RESET is completed in endpoint */
 	mhi_ep_mmio_reset(mhi_cntrl);
 	cur_state = mhi_cntrl->mhi_state;
-	spin_unlock_bh(&mhi_cntrl->state_lock);
 
 	/*
 	 * Only proceed further if the reset is due to SYS_ERR. The host will

@@ -1014,6 +1014,8 @@ static void mhi_ep_reset_worker(struct work_struct *work)
 	 */
 	if (cur_state == MHI_STATE_SYS_ERR)
 		mhi_ep_power_up(mhi_cntrl);
+
+	mutex_unlock(&mhi_cntrl->state_lock);
 }
 
 /*

@@ -1386,8 +1388,8 @@ int mhi_ep_register_controller(struct mhi_ep_cntrl *mhi_cntrl,
 
 	INIT_LIST_HEAD(&mhi_cntrl->st_transition_list);
 	INIT_LIST_HEAD(&mhi_cntrl->ch_db_list);
-	spin_lock_init(&mhi_cntrl->state_lock);
 	spin_lock_init(&mhi_cntrl->list_lock);
+	mutex_init(&mhi_cntrl->state_lock);
 	mutex_init(&mhi_cntrl->event_lock);
 
 	/* Set MHI version and AMSS EE before enumeration */
drivers/bus/mhi/ep/sm.c +24 -18

104 lines not on this page · raw message

include/linux/mhi_ep.h +2 -2
index 478aece17046..f198a8ac7ee7 100644
@@ -70,8 +70,8 @@ struct mhi_ep_db_info {
  * @cmd_ctx_cache_phys: Physical address of the host command context cache
  * @chdb: Array of channel doorbell interrupt info
  * @event_lock: Lock for protecting event rings
- * @list_lock: Lock for protecting state transition and channel doorbell lists
  * @state_lock: Lock for protecting state transitions
+ * @list_lock: Lock for protecting state transition and channel doorbell lists
  * @st_transition_list: List of state transitions
  * @ch_db_list: List of queued channel doorbells
  * @wq: Dedicated workqueue for handling rings and state changes

@@ -117,8 +117,8 @@ struct mhi_ep_cntrl {
 
 	struct mhi_ep_db_info chdb[4];
 	struct mutex event_lock;
+	struct mutex state_lock;
 	spinlock_t list_lock;
-	spinlock_t state_lock;
 
 	struct list_head st_transition_list;
 	struct list_head ch_db_list;