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