Re: [PATCH 4/6] ufs: Fix a race condition in the tracing code

Alim Akhtar
2019-12-27T01:22:01Z

On Wed, Dec 25, 2019 at 3:34 AM Bart Van Assche <bvanassche@acm.org> wrote:
>
> Starting execution of a command before tracing a command may cause the
> completion handler to free data while it is being traced. Fix this race
> by tracing a command before it is submitted.
>
> Cc: Bean Huo <beanhuo@micron.com>
> Cc: Can Guo <cang@codeaurora.org>
> Cc: Avri Altman <avri.altman@wdc.com>
> Cc: Stanley Chu <stanley.chu@mediatek.com>
> Cc: Tomas Winkler <tomas.winkler@intel.com>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
> drivers/scsi/ufs/ufshcd.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 80b028ba39e9..4d9bb1932b39 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1875,12 +1875,12 @@ void ufshcd_send_command(struct ufs_hba *hba, unsigned int task_tag)
> {
> hba->lrb[task_tag].issue_time_stamp = ktime_get();
> hba->lrb[task_tag].compl_time_stamp = ktime_set(0, 0);
> + ufshcd_add_command_trace(hba, task_tag, "send");
> ufshcd_clk_scaling_start_busy(hba);
> __set_bit(task_tag, &hba->outstanding_reqs);
> ufshcd_writel(hba, 1 << task_tag, REG_UTP_TRANSFER_REQ_DOOR_BELL);
> /* Make sure that doorbell is committed immediately */
> wmb();
> - ufshcd_add_command_trace(hba, task_tag, "send");
> }
>
> /**

--
Regards,
Alim