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@xxxxxxx>
Cc: Mike Christie <michaelc@xxxxxxxxxxx>
Cc: James Bottomley <JBottomley@xxxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Joe Lawrence <jdl1291@xxxxxxxxx>
Cc: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
---
drivers/scsi/scsi_lib.c | 7 ++++---
drivers/scsi/scsi_sysfs.c | 11 +++++++++--
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 082c1e5..b722a8b 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -158,10 +158,11 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
* that are already in the queue.
*/
spin_lock_irqsave(q->queue_lock, flags);
- blk_requeue_request(q, cmd->request);
+ if (!blk_queue_dead(q)) {
+ blk_requeue_request(q, cmd->request);
+ kblockd_schedule_work(q, &device->requeue_work);
+ }
spin_unlock_irqrestore(q->queue_lock, flags);
-
- kblockd_schedule_work(q, &device->requeue_work);
}
/*
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 42c35ff..efffc92 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -966,13 +966,20 @@ 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);
}
--
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