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scsi: set timed out out mq requests to complete 

The scsi block layer requires requests claimed by the error handling be
completed by the error handler. A previous commit allowed completions
to proceed for blk-mq, breaking that assumption.

This patch prevents completions that may race with the timeout handler
by marking the state to complete, restoring the previous behavior.

Fixes: 12f5b931 ("blk-mq: Remove generation seqeunce")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
hifive-unleashed-5.1
Keith Busch 2018-07-23 08:37:51 -06:00 committed by Jens Axboe
parent 0fc09f9209
commit 065990bd19
1 changed files with 14 additions and 0 deletions
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14
drivers/scsi/scsi_error.c
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@ -296,6 +296,20 @@ enum blk_eh_timer_return scsi_times_out(struct request *req)
rtn = host->hostt->eh_timed_out(scmd);
if (rtn == BLK_EH_DONE) {
/*
* For blk-mq, we must set the request state to complete now
* before sending the request to the scsi error handler. This
* will prevent a use-after-free in the event the LLD manages
* to complete the request before the error handler finishes
* processing this timed out request.
*
* If the request was already completed, then the LLD beat the
* time out handler from transferring the request to the scsi
* error handler. In that case we can return immediately as no
* further action is required.
*/
if (req->q->mq_ops && !blk_mq_mark_complete(req))
return rtn;
if (scsi_abort_command(scmd) != SUCCESS) {
set_host_byte(scmd, DID_TIME_OUT);
scsi_eh_scmd_add(scmd);