On 19/11/22 01:37, Bart Van Assche wrote:
> Fix the following issues in ufshcd_poll():
> - If polling succeeds, return a positive value.
> - Do not complete polling requests from interrupt context because the
> block layer expects these requests to be completed from thread
> context. From block/bio.c:
>
> If REQ_ALLOC_CACHE is set, the final put of the bio MUST be done
> from process context, not hard/soft IRQ.
>
> Fixes: eaab9b573054 ("scsi: ufs: Implement polling support")
> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
Reviewed-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
>
> Changes compared to v1:
> - Made sure that polled requests are not completed from interrupt context.
>
> drivers/ufs/core/ufshcd.c | 28 ++++++++++++++++++++++++++--
> 1 file changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 768cb49d269c..b4bf3c3bef0c 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -5344,6 +5344,26 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba,
> }
> }
>
> +/* Any value that is not an existing queue number is fine for this constant. */
> +enum {
> + UFSHCD_POLL_FROM_INTERRUPT_CONTEXT = -1
> +};
> +
> +static void ufshcd_clear_polled(struct ufs_hba *hba,
> + unsigned long *completed_reqs)
> +{
> + int tag;
> +
> + for_each_set_bit(tag, completed_reqs, hba->nutrs) {
> + struct scsi_cmnd *cmd = hba->lrb[tag].cmd;
> +
> + if (!cmd)
> + continue;
> + if (scsi_cmd_to_rq(cmd)->cmd_flags & REQ_POLLED)
> + __clear_bit(tag, completed_reqs);
> + }
> +}
> +
> /*
> * Returns > 0 if one or more commands have been completed or 0 if no
> * requests have been completed.
> @@ -5360,13 +5380,17 @@ static int ufshcd_poll(struct Scsi_Host *shost, unsigned int queue_num)
> WARN_ONCE(completed_reqs & ~hba->outstanding_reqs,
> "completed: %#lx; outstanding: %#lx\n", completed_reqs,
> hba->outstanding_reqs);
> + if (queue_num == UFSHCD_POLL_FROM_INTERRUPT_CONTEXT) {
> + /* Do not complete polled requests from interrupt context. */
> + ufshcd_clear_polled(hba, &completed_reqs);
> + }
> hba->outstanding_reqs &= ~completed_reqs;
> spin_unlock_irqrestore(&hba->outstanding_lock, flags);
>
> if (completed_reqs)
> __ufshcd_transfer_req_compl(hba, completed_reqs);
>
> - return completed_reqs;
> + return completed_reqs != 0;
> }
>
> /**
> @@ -5397,7 +5421,7 @@ static irqreturn_t ufshcd_transfer_req_compl(struct ufs_hba *hba)
> * Ignore the ufshcd_poll() return value and return IRQ_HANDLED since we
> * do not want polling to trigger spurious interrupt complaints.
> */
> - ufshcd_poll(hba->host, 0);
> + ufshcd_poll(hba->host, UFSHCD_POLL_FROM_INTERRUPT_CONTEXT);
>
> return IRQ_HANDLED;
> }
