Re: [PATCH v10 2/2] ufs: core: requeue aborted request

[Bart Van Assche <bvanassche@acm.org>]

On 10/2/24 5:42 AM, Peter Wang (王信友) wrote:
> This patch merely aligns with the approach of SDB mode
> and does not involve the flow of scsi_done. Besides,
> I don't see any issue with concurrency between
> ufshcd_abort_one() calling ufshcd_try_to_abort_task()
> and scsi_done(). Can you point out the specific flow where
> the problem occurs? If there is one, shouldn't SDB mode
> have the same issue?

Hi Peter,

Correct, my comment applies to both legacy mode and MCQ mode. From the 
section in the UFS standard about ABORT TASK: "A response of FUNCTION
COMPLETE shall indicate that the command was aborted or was not in the 
task set." In other words, if a command completes just before 
ufshcd_try_to_abort_task() calls ufshcd_issue_tm_cmd(), then
ufshcd_try_to_abort_task() will call ufshcd_clear_cmd() for a command
that has already completed. In legacy mode, this call will succeed.
Hence, both ufshcd_compl_one_cqe() and ufshcd_abort_all() will call
ufshcd_release(hba). This will cause hba->clk_gating.active_reqs to be
decremented twice instead of only once. Do you agree that this can
happen and also that it should be prevented that this happens?

Thanks,

Bart.