On 15/09/21 1:28 am, Bart Van Assche wrote:

On 9/13/21 9:55 PM, Adrian Hunter wrote:

quoted

On 13/09/21 11:11 pm, Bart Van Assche wrote: >> What am I missing?

You have not responded to the issues raised by
"scsi: ufs: Synchronize SCSI and UFS error handling"

Because one of the follow-up messages to that patch was so cryptic that I
did not comprehend it. Anyway, based on the patch at the start of this email
thread I assume that the deadlock is caused by calling blk_get_request()
without the BLK_MQ_REQ_NOWAIT flag from inside a SCSI error handler. How
about fixing this by removing the code that submits a REQUEST SENSE command
and calling scsi_report_bus_reset() or scsi_report_device_reset() instead?
ufshcd_reset_and_restore() already uses that approach to make sure that the
unit attention condition triggered by a reset is not reported to the SCSI
command submitter. I think only if needs_restore == true and
needs_reset == false that ufshcd_err_handler() can trigger a UA condition
without calling scsi_report_bus_reset().

The following code from scsi_error.c makes sure that the UA after a reset
does not reach the upper-level driver:

    case NOT_READY:
    case UNIT_ATTENTION:
        /*
         * if we are expecting a cc/ua because of a bus reset that we
         * performed, treat this just as a retry.  otherwise this is
         * information that we should pass up to the upper-level driver
         * so that we can deal with it there.
         */
        if (scmd->device->expecting_cc_ua) {
            /*
             * Because some device does not queue unit
             * attentions correctly, we carefully check
             * additional sense code and qualifier so as
             * not to squash media change unit attention.
             */
            if (sshdr.asc != 0x28 || sshdr.ascq != 0x00) {
                scmd->device->expecting_cc_ua = 0;
                return NEEDS_RETRY;
            }
        }

Bart.

Thanks for the idea.  Unfortunately it does not work for pass-through
requests, refer scsi_noretry_cmd().  sdev_ufs_device and sdev_rpmb are
used with pass-through requests.