Messages in this thread Patch in this message | | | From | John Garry <> | Subject | [PATCH] scsi: hisi_sas: Fix memory ordering in hisi_sas_task_deliver() | Date | Tue, 17 May 2022 16:04:21 +0800 |
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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().
Fixes: 26fc0ea74fcb ("scsi: libsas: Drop SAS_TASK_AT_INITIATOR") Reported-by: Yihang Li <liyihang6@hisilicon.com> Tested-by: Yihang Li <liyihang6@hisilicon.com> Signed-off-by: John Garry <john.garry@huawei.com> --- Hi Martin, Please consider for v5.18, thanks!
diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c index 4bda2f6cb352..f56dd01230ce 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); -- 2.26.2
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