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

[Can Guo <cang@codeaurora.org>]

On 2019-12-25 06:02, Bart Van Assche 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>
> ---
>  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");

How about moving it after __set_bit(task_tag, &hba->outstanding_reqs);?

Thanks,

Can Guo.

>  	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");
>  }
> 
>  /**