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scsi: ufs: core: Let the sq_lock protect sq_tail_slot access

Message ID 1702913550-20631-1-git-send-email-quic_cang@quicinc.com
State New
Headers show
Series scsi: ufs: core: Let the sq_lock protect sq_tail_slot access | expand

Commit Message

Can Guo Dec. 18, 2023, 3:32 p.m. UTC
If access sq_tail_slot without the protection from the sq_lock, race
condition can have multiple SQEs copied to duplicate SQE slot(s), which can
lead to multiple incredible stability issues. Fix it by moving the *dest
initialization, in ufshcd_send_command(), back under protection from the
sq_lock.

Fixes: 3c85f087faec ("scsi: ufs: mcq: Use pointer arithmetic in ufshcd_send_command()")
Signed-off-by: Can Guo <quic_cang@quicinc.com>

Comments

Manivannan Sadhasivam Dec. 20, 2023, 5 p.m. UTC | #1
On Wed, Dec 20, 2023 at 08:35:18AM -0800, Bart Van Assche wrote:
> On 12/20/23 06:50, Manivannan Sadhasivam wrote:
> > On Mon, Dec 18, 2023 at 07:32:17AM -0800, Can Guo wrote:
> > > If access sq_tail_slot without the protection from the sq_lock, race
> > > condition can have multiple SQEs copied to duplicate SQE slot(s), which can
> > > lead to multiple incredible stability issues. Fix it by moving the *dest
> > > initialization, in ufshcd_send_command(), back under protection from the
> > > sq_lock.
> > > 
> > > Fixes: 3c85f087faec ("scsi: ufs: mcq: Use pointer arithmetic in ufshcd_send_command()")
> > 
> > Cc: stable@vger.kernel.org
> 
> Hmm ... is the "Cc: stable" tag really required if a "Fixes:" tag is present?
> 

Yes it is required as I pointed out in the other thread.

- Mani

> Bart.
>
Bao D. Nguyen Jan. 2, 2024, 8:33 p.m. UTC | #2
On 12/18/2023 7:32 AM, Can Guo wrote:
> If access sq_tail_slot without the protection from the sq_lock, race
> condition can have multiple SQEs copied to duplicate SQE slot(s), which can
> lead to multiple incredible stability issues. Fix it by moving the *dest
> initialization, in ufshcd_send_command(), back under protection from the
> sq_lock.
> 
> Fixes: 3c85f087faec ("scsi: ufs: mcq: Use pointer arithmetic in ufshcd_send_command()")
> Signed-off-by: Can Guo <quic_cang@quicinc.com>
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index ae9936f..2994aac 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -2274,9 +2274,10 @@ 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);

Reviewed and Tested-by: Bao D. Nguyen <quic_nguyenb@quicinc.com>
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Patch

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index ae9936f..2994aac 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -2274,9 +2274,10 @@  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);