[PATCH v1] ufs: get target SQ entry within critical section

[Kiwoong Kim]

In IO centric scenarios, especially during a period that
many IO requests are submitted to a same HW queue at the same
time, it's found that one reqeust overwrote a SQ entry
that had been already occupied by another request submitted
in the past. And it eventually led to command timed-out
because one of two requests were overwritten, which could not
be completed.

[   74.995185][  T176] exynos-ufs 17100000.ufs: ufshcd_abort: Device abort task at tag 30

Signed-off-by: Kiwoong Kim <kwmad.kim@xxxxxxxxxxx>
---
 drivers/ufs/core/ufshcd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 7bc3fc4..da1a9c0 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -2199,9 +2199,10 @@ void ufshcd_send_command(struct ufs_hba *hba, unsigned int task_tag,
 	if (is_mcq_enabled(hba)) {
 		int utrd_size = sizeof(struct utp_transfer_req_desc);
 		struct utp_transfer_req_desc *src = lrbp->utr_descriptor_ptr;
-		struct utp_transfer_req_desc *dest = hwq->sqe_base_addr + hwq->sq_tail_slot;
+		struct utp_transfer_req_desc *dest;
 
 		spin_lock(&hwq->sq_lock);
+		dest = hwq->sqe_base_addr + hwq->sq_tail_slot;
 		memcpy(dest, src, utrd_size);
 		ufshcd_inc_sq_tail(hwq);
 		spin_unlock(&hwq->sq_lock);
-- 
2.7.4