This is a note to let you know that I've just added the patch titled
scsi: ufs: core: Fix another task management completion race
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
scsi-ufs-core-fix-another-task-management-completion.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7fa3f5a8a4f74da9b14620fa3ef689deaef3b687
Author: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Date: Mon Nov 8 08:48:15 2021 +0200
scsi: ufs: core: Fix another task management completion race
[ Upstream commit 5cb37a26355d79ab290220677b1b57d28e99a895 ]
hba->outstanding_tasks, which is read under host_lock spinlock, tells the
interrupt handler what task management tags are in use by the driver. The
doorbell register bits indicate which tags are in use by the hardware. A
doorbell bit that is 0 is because the bit has yet to be set by the driver,
or because the task is complete. It is only possible to disambiguate the 2
cases, if reading/writing the doorbell register is synchronized with
reading/writing hba->outstanding_tasks.
For that reason, reading REG_UTP_TASK_REQ_DOOR_BELL must be done under
spinlock.
Link: https://lore.kernel.org/r/20211108064815.569494-3-adrian.hunter@xxxxxxxxx
Fixes: f5ef336fd2e4 ("scsi: ufs: core: Fix task management completion")
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 3d0da8b3fed8a..55f2e4d6f10b7 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6382,9 +6382,8 @@ static irqreturn_t ufshcd_tmc_handler(struct ufs_hba *hba)
irqreturn_t ret = IRQ_NONE;
int tag;
- pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL);
-
spin_lock_irqsave(hba->host->host_lock, flags);
+ pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL);
issued = hba->outstanding_tasks & ~pending;
for_each_set_bit(tag, &issued, hba->nutmrs) {
struct request *req = hba->tmf_rqs[tag];
