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authorBart Van Assche <bvanassche@acm.org>2012-06-29 19:36:07 +0400
committerJames Bottomley <JBottomley@Parallels.com>2012-07-20 11:58:41 +0400
commitb485462aca7df4e32bcf7efb6f84a69e8b640243 (patch)
tree744345ebe5c761a46a28a495fae82b6dd4d9e28b /drivers/scsi
parent84feb1664e5e6823105414df77740fda70846b99 (diff)
downloadlinux-b485462aca7df4e32bcf7efb6f84a69e8b640243.tar.xz
[SCSI] Stop accepting SCSI requests before removing a device
Avoid that the code for requeueing SCSI requests triggers a crash by making sure that that code isn't scheduled anymore after a device has been removed. Also, source code inspection of __scsi_remove_device() revealed a race condition in this function: no new SCSI requests must be accepted for a SCSI device after device removal started. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Mike Christie <michaelc@cs.wisc.edu> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/scsi_lib.c7
-rw-r--r--drivers/scsi/scsi_sysfs.c11
2 files changed, 13 insertions, 5 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 8af6a6497c4f..b58327758c58 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -155,13 +155,14 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
/*
* Requeue this command. It will go before all other commands
- * that are already in the queue.
+ * that are already in the queue. Schedule requeue work under
+ * lock such that the kblockd_schedule_work() call happens
+ * before blk_cleanup_queue() finishes.
*/
spin_lock_irqsave(q->queue_lock, flags);
blk_requeue_request(q, cmd->request);
- spin_unlock_irqrestore(q->queue_lock, flags);
-
kblockd_schedule_work(q, &device->requeue_work);
+ spin_unlock_irqrestore(q->queue_lock, flags);
}
/*
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 9aa578a5da11..d19d7e99626d 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -967,13 +967,20 @@ void __scsi_remove_device(struct scsi_device *sdev)
device_del(dev);
} else
put_device(&sdev->sdev_dev);
+
+ /*
+ * Stop accepting new requests and wait until all queuecommand() and
+ * scsi_run_queue() invocations have finished before tearing down the
+ * device.
+ */
scsi_device_set_state(sdev, SDEV_DEL);
+ blk_cleanup_queue(sdev->request_queue);
+ cancel_work_sync(&sdev->requeue_work);
+
if (sdev->host->hostt->slave_destroy)
sdev->host->hostt->slave_destroy(sdev);
transport_destroy_device(dev);
- /* Freeing the queue signals to block that we're done */
- blk_cleanup_queue(sdev->request_queue);
put_device(dev);
}