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[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>
This commit is contained in:
Bart Van Assche 2012-06-29 15:36:07 +00:00 committed by James Bottomley
parent 84feb1664e
commit b485462aca
2 changed files with 13 additions and 5 deletions
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7
drivers/scsi/scsi_lib.c
View File

@ -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);
}
/*

11
drivers/scsi/scsi_sysfs.c
View File

@ -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);
}