Avoid that the sdev reference count can drop to zero before a queue is run by scsi_run_queue().
Signed-off-by: Bart Van Assche <bvanass...@acm.org> Reported-and-tested-by: Chanho Min <chanho....@lge.com> Reference: http://lkml.org/lkml/2012/8/2/96 Acked-by: Tejun Heo <t...@kernel.org> Reviewed-by: Mike Christie <micha...@cs.wisc.edu> Cc: Jens Axboe <ax...@kernel.dk> Cc: <sta...@vger.kernel.org> --- drivers/scsi/scsi_lib.c | 16 +++++++++++----- drivers/scsi/scsi_sysfs.c | 14 +++++++++++++- 2 files changed, 24 insertions(+), 6 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index f1bf5af..5c67339 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -452,11 +452,17 @@ static void scsi_run_queue(struct request_queue *q) continue; } - spin_unlock(shost->host_lock); - spin_lock(sdev->request_queue->queue_lock); - __blk_run_queue(sdev->request_queue); - spin_unlock(sdev->request_queue->queue_lock); - spin_lock(shost->host_lock); + /* + * Obtain a reference before unlocking the host_lock such that + * the sdev can't disappear before blk_run_queue() is invoked. + */ + get_device(&sdev->sdev_gendev); + spin_unlock_irqrestore(shost->host_lock, flags); + + blk_run_queue(sdev->request_queue); + put_device(&sdev->sdev_gendev); + + spin_lock_irqsave(shost->host_lock, flags); } /* put any unprocessed entries back */ list_splice(&starved_list, &shost->starved_list); diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index ce5224c..2ff7ba5 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -348,7 +348,6 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) starget->reap_ref++; list_del(&sdev->siblings); list_del(&sdev->same_target_siblings); - list_del(&sdev->starved_entry); spin_unlock_irqrestore(sdev->host->host_lock, flags); cancel_work_sync(&sdev->event_work); @@ -956,6 +955,8 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev) void __scsi_remove_device(struct scsi_device *sdev) { struct device *dev = &sdev->sdev_gendev; + struct Scsi_Host *shost = sdev->host; + unsigned long flags; if (sdev->is_visible) { if (scsi_device_set_state(sdev, SDEV_CANCEL) != 0) @@ -977,6 +978,17 @@ void __scsi_remove_device(struct scsi_device *sdev) blk_cleanup_queue(sdev->request_queue); cancel_work_sync(&sdev->requeue_work); + /* + * Remove a SCSI device from the starved list after blk_cleanup_queue() + * finished such that scsi_request_fn() can't add it back to that list. + * Also remove an sdev from the starved list before invoking + * put_device() such that get_device() is guaranteed to succeed for an + * sdev present on the starved list. + */ + spin_lock_irqsave(shost->host_lock, flags); + list_del(&sdev->starved_entry); + spin_unlock_irqrestore(shost->host_lock, flags); + if (sdev->host->hostt->slave_destroy) sdev->host->hostt->slave_destroy(sdev); transport_destroy_device(dev); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
