This is a note to let you know that I've just added the patch titled
scsi: hisi_sas: Fix memory ordering in hisi_sas_task_deliver()
to the 5.18-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-hisi_sas-fix-memory-ordering-in-hisi_sas_task_d.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9d1f2c535f8af2c7070cbe1cfd1828d44e4dbce1
Author: John Garry <john.garry@xxxxxxxxxx>
Date: Tue May 17 16:04:21 2022 +0800
scsi: hisi_sas: Fix memory ordering in hisi_sas_task_deliver()
[ Upstream commit 6c6ac8b7773f05f93dc4e4044686e059d1f78dea ]
The memories for the slot should be observed to be written prior to
observing the slot as ready.
Prior to commit 26fc0ea74fcb ("scsi: libsas: Drop SAS_TASK_AT_INITIATOR"),
we had a spin_lock() + spin_unlock() immediately before marking the slot as
ready. The spin_unlock() - with release semantics - caused the slot memory
to be observed to be written.
Now that the spin_lock() + spin_unlock() is gone, use a smp_wmb().
Link: https://lore.kernel.org/r/1652774661-12935-1-git-send-email-john.garry@xxxxxxxxxx
Fixes: 26fc0ea74fcb ("scsi: libsas: Drop SAS_TASK_AT_INITIATOR")
Reported-by: Yihang Li <liyihang6@xxxxxxxxxxxxx>
Tested-by: Yihang Li <liyihang6@xxxxxxxxxxxxx>
Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
index 86cbfab78dfe..849cc5fc86af 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_main.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
@@ -446,6 +446,8 @@ void hisi_sas_task_deliver(struct hisi_hba *hisi_hba,
return;
}
+ /* Make slot memories observable before marking as ready */
+ smp_wmb();
WRITE_ONCE(slot->ready, 1);
spin_lock(&dq->lock);
