async_sas_ata_eh(), which will call scsi_eh_finish_cmd() in some case, would be performed simultaneously in sas_ata_strategy_handler(). In this case, ->host_failed may be decreased simultaneously in scsi_eh_finish_cmd() on different CPUs, and become abnormal. It will lead to permanently inequal between ->host_failed and ->host_busy. Then SCSI error handler thread won't become running, SCSI errors after that won't be handled forever. Use atomic type for ->host_failed to fix this race. Signed-off-by: Wei Fang <fangwei1@xxxxxxxxxx> --- drivers/ata/libata-eh.c | 2 +- drivers/scsi/libsas/sas_scsi_host.c | 5 +++-- drivers/scsi/scsi.c | 2 +- drivers/scsi/scsi_error.c | 15 +++++++++------ drivers/scsi/scsi_lib.c | 3 ++- include/scsi/scsi_host.h | 2 +- 6 files changed, 17 insertions(+), 12 deletions(-) diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c index 961acc7..a0e7612 100644 --- a/drivers/ata/libata-eh.c +++ b/drivers/ata/libata-eh.c @@ -606,7 +606,7 @@ void ata_scsi_error(struct Scsi_Host *host) ata_scsi_port_error_handler(host, ap); /* finish or retry handled scmd's and clean up */ - WARN_ON(host->host_failed || !list_empty(&eh_work_q)); + WARN_ON(atomic_read(&host->host_failed) || !list_empty(&eh_work_q)); DPRINTK("EXIT\n"); } diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c index 519dac4..8d74003 100644 --- a/drivers/scsi/libsas/sas_scsi_host.c +++ b/drivers/scsi/libsas/sas_scsi_host.c @@ -757,7 +757,8 @@ retry: spin_unlock_irq(shost->host_lock); SAS_DPRINTK("Enter %s busy: %d failed: %d\n", - __func__, atomic_read(&shost->host_busy), shost->host_failed); + __func__, atomic_read(&shost->host_busy), + atomic_read(&shost->host_failed)); /* * Deal with commands that still have SAS tasks (i.e. they didn't * complete via the normal sas_task completion mechanism), @@ -800,7 +801,7 @@ out: SAS_DPRINTK("--- Exit %s: busy: %d failed: %d tries: %d\n", __func__, atomic_read(&shost->host_busy), - shost->host_failed, tries); + atomic_read(&shost->host_failed), tries); } enum blk_eh_timer_return sas_scsi_timed_out(struct scsi_cmnd *cmd) diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index 1deb6ad..7840915 100644 --- a/drivers/scsi/scsi.c +++ b/drivers/scsi/scsi.c @@ -527,7 +527,7 @@ void scsi_log_completion(struct scsi_cmnd *cmd, int disposition) scmd_printk(KERN_INFO, cmd, "scsi host busy %d failed %d\n", atomic_read(&cmd->device->host->host_busy), - cmd->device->host->host_failed); + atomic_read(&cmd->device->host->host_failed)); } } } diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index 984ddcb..f37666f 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -62,7 +62,8 @@ static int scsi_try_to_abort_cmd(struct scsi_host_template *, /* called with shost->host_lock held */ void scsi_eh_wakeup(struct Scsi_Host *shost) { - if (atomic_read(&shost->host_busy) == shost->host_failed) { + if (atomic_read(&shost->host_busy) == + atomic_read(&shost->host_failed)) { trace_scsi_eh_wakeup(shost); wake_up_process(shost->ehandler); SCSI_LOG_ERROR_RECOVERY(5, shost_printk(KERN_INFO, shost, @@ -250,7 +251,7 @@ int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag) eh_flag &= ~SCSI_EH_CANCEL_CMD; scmd->eh_eflags |= eh_flag; list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q); - shost->host_failed++; + atomic_inc(&shost->host_failed); scsi_eh_wakeup(shost); out_unlock: spin_unlock_irqrestore(shost->host_lock, flags); @@ -1127,7 +1128,7 @@ static int scsi_eh_action(struct scsi_cmnd *scmd, int rtn) */ void scsi_eh_finish_cmd(struct scsi_cmnd *scmd, struct list_head *done_q) { - scmd->device->host->host_failed--; + atomic_dec(&scmd->device->host->host_failed); scmd->eh_eflags = 0; list_move_tail(&scmd->eh_entry, done_q); } @@ -2190,8 +2191,10 @@ int scsi_error_handler(void *data) if (kthread_should_stop()) break; - if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) || - shost->host_failed != atomic_read(&shost->host_busy)) { + if ((atomic_read(&shost->host_failed) == 0 && + shost->host_eh_scheduled == 0) || + (atomic_read(&shost->host_failed) != + atomic_read(&shost->host_busy))) { SCSI_LOG_ERROR_RECOVERY(1, shost_printk(KERN_INFO, shost, "scsi_eh_%d: sleeping\n", @@ -2205,7 +2208,7 @@ int scsi_error_handler(void *data) shost_printk(KERN_INFO, shost, "scsi_eh_%d: waking up %d/%d/%d\n", shost->host_no, shost->host_eh_scheduled, - shost->host_failed, + atomic_read(&shost->host_failed), atomic_read(&shost->host_busy))); /* diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 8106515..fb3cc5d 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -318,7 +318,8 @@ void scsi_device_unbusy(struct scsi_device *sdev) atomic_dec(&starget->target_busy); if (unlikely(scsi_host_in_recovery(shost) && - (shost->host_failed || shost->host_eh_scheduled))) { + (atomic_read(&shost->host_failed) || + shost->host_eh_scheduled))) { spin_lock_irqsave(shost->host_lock, flags); scsi_eh_wakeup(shost); spin_unlock_irqrestore(shost->host_lock, flags); diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index fcfa3d7..654435f 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -576,7 +576,7 @@ struct Scsi_Host { atomic_t host_busy; /* commands actually active on low-level */ atomic_t host_blocked; - unsigned int host_failed; /* commands that failed. + atomic_t host_failed; /* commands that failed. protected by host_lock */ unsigned int host_eh_scheduled; /* EH scheduled without command */ -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html