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authorBart Van Assche <bvanassche@acm.org>2022-10-18 23:29:49 +0300
committerMartin K. Petersen <martin.petersen@oracle.com>2022-10-22 06:25:59 +0300
commit978b7922d3dca672b41bb4b8ce6c06ab77112741 (patch)
treee54031ca580b303bb49ece4e575ed20f2cdf5676 /drivers/scsi
parent24b3e45ca9c53185baec34488efcb75bbe162f7a (diff)
downloadlinux-978b7922d3dca672b41bb4b8ce6c06ab77112741.tar.xz
scsi: core: Fix a race between scsi_done() and scsi_timeout()
If there is a race between scsi_done() and scsi_timeout() and if scsi_timeout() loses the race, scsi_timeout() should not reset the request timer. Hence change the return value for this case from BLK_EH_RESET_TIMER into BLK_EH_DONE. Although the block layer holds a reference on a request (req->ref) while calling a timeout handler, restarting the timer (blk_add_timer()) while a request is being completed is racy. Reviewed-by: Mike Christie <michael.christie@oracle.com> Cc: Keith Busch <kbusch@kernel.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Ming Lei <ming.lei@redhat.com> Cc: John Garry <john.garry@huawei.com> Cc: Hannes Reinecke <hare@suse.de> Reported-by: Adrian Hunter <adrian.hunter@intel.com> Fixes: 15f73f5b3e59 ("blk-mq: move failure injection out of blk_mq_complete_request") Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20221018202958.1902564-2-bvanassche@acm.org Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/scsi_error.c14
1 files changed, 3 insertions, 11 deletions
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 6995c8979230..02520f912306 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -343,19 +343,11 @@ enum blk_eh_timer_return scsi_timeout(struct request *req)
if (rtn == BLK_EH_DONE) {
/*
- * Set the command to complete first in order to prevent a real
- * completion from releasing the command while error handling
- * is using it. If the command was already completed, then the
- * lower level driver beat the timeout handler, and it is safe
- * to return without escalating error recovery.
- *
- * If timeout handling lost the race to a real completion, the
- * block layer may ignore that due to a fake timeout injection,
- * so return RESET_TIMER to allow error handling another shot
- * at this command.
+ * If scsi_done() has already set SCMD_STATE_COMPLETE, do not
+ * modify *scmd.
*/
if (test_and_set_bit(SCMD_STATE_COMPLETE, &scmd->state))
- return BLK_EH_RESET_TIMER;
+ return BLK_EH_DONE;
if (scsi_abort_command(scmd) != SUCCESS) {
set_host_byte(scmd, DID_TIME_OUT);
scsi_eh_scmd_add(scmd);