From 7daf480483e60898f30e0a2a84fecada7a7cfac0 Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Mon, 31 Mar 2014 16:37:34 +0200 Subject: [PATCH] [SCSI] Fix USB deadlock caused by SCSI error handling USB requires that every command be aborted first before we escalate to reset. In particular, USB will deadlock if we try to reset first before aborting the command. Unfortunately, the flag we use to tell if a command has already been aborted: SCSI_EH_ABORT_SCHEDULED is not cleared properly leading to cases where we can requeue a command with the flag set and proceed immediately to reset if it fails (thus causing USB to deadlock). Fix by clearing the SCSI_EH_ABORT_SCHEDULED flag if it has been set. Which means this will be the second time scsi_abort_command() has been called for the same command. IE the first abort went out, did its thing, but now the same command has timed out again. So this flag gets cleared, and scsi_abort_command() returns FAILED, and _no_ asynchronous abort is being scheduled. scsi_times_out() will then proceed to call scsi_eh_scmd_add(). But as we've cleared the SCSI_EH_ABORT_SCHEDULED flag the SCSI_EH_CANCEL_CMD flag will continue to be set, and the command will be aborted with the main SCSI EH routine. Reported-by: Alan Stern Tested-by: Andreas Reis Signed-off-by: Hannes Reinecke Signed-off-by: James Bottomley --- drivers/scsi/scsi_error.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index 2953bfa92da7..ad064d2d730b 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -189,6 +189,7 @@ scsi_abort_command(struct scsi_cmnd *scmd) /* * Retry after abort failed, escalate to next level. */ + scmd->eh_eflags &= ~SCSI_EH_ABORT_SCHEDULED; SCSI_LOG_ERROR_RECOVERY(3, scmd_printk(KERN_INFO, scmd, "scmd %p previous abort failed\n", scmd));