forked from luck/tmp_suning_uos_patched
[SCSI] put stricter guards on queue dead checks
SCSI uses request_queue->queuedata == NULL as a signal that the queue is dying. We set this state in the sdev release function. However, this allows a small window where we release the last reference but haven't quite got to this stage yet and so something will try to take a reference in scsi_request_fn and oops. It's very rare, but we had a report here, so we're pushing this as a bug fix The actual fix is to set request_queue->queuedata to NULL in scsi_remove_device() before we drop the reference. This causes correct automatic rejects from scsi_request_fn as people who hold additional references try to submit work and prevents anything from getting a new reference to the sdev that way. Cc: stable@kernel.org Signed-off-by: James Bottomley <James.Bottomley@suse.de>
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@ -322,14 +322,8 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
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kfree(evt);
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}
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if (sdev->request_queue) {
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sdev->request_queue->queuedata = NULL;
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/* user context needed to free queue */
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scsi_free_queue(sdev->request_queue);
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/* temporary expedient, try to catch use of queue lock
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* after free of sdev */
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sdev->request_queue = NULL;
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}
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/* NULL queue means the device can't be used */
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sdev->request_queue = NULL;
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scsi_target_reap(scsi_target(sdev));
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@ -937,6 +931,12 @@ void __scsi_remove_device(struct scsi_device *sdev)
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if (sdev->host->hostt->slave_destroy)
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sdev->host->hostt->slave_destroy(sdev);
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transport_destroy_device(dev);
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/* cause the request function to reject all I/O requests */
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sdev->request_queue->queuedata = NULL;
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/* Freeing the queue signals to block that we're done */
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scsi_free_queue(sdev->request_queue);
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put_device(dev);
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}
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