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authorJames Bottomley <James.Bottomley@suse.de>2011-04-22 10:39:59 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2011-05-09 15:06:35 -0700
commit1f74c190e1e97a38823c07fdc71780580a0fc03f (patch)
treed43044a1069b1cf6a7757a73302028900d5fc3a2 /drivers
parent52adc5764d7cbeddce5e70aac1a14f534d004b60 (diff)
downloadlinux-linaro-android-1f74c190e1e97a38823c07fdc71780580a0fc03f.tar.gz
put stricter guards on queue dead checks
commit 86cbfb5607d4b81b1a993ff689bbd2addd5d3a9b upstream. 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. Signed-off-by: James Bottomley <James.Bottomley@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/scsi/scsi_sysfs.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 490ce213204..360b7cbadb4 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -322,14 +322,8 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
kfree(evt);
}
- if (sdev->request_queue) {
- sdev->request_queue->queuedata = NULL;
- /* user context needed to free queue */
- scsi_free_queue(sdev->request_queue);
- /* temporary expedient, try to catch use of queue lock
- * after free of sdev */
- sdev->request_queue = NULL;
- }
+ /* NULL queue means the device can't be used */
+ sdev->request_queue = NULL;
scsi_target_reap(scsi_target(sdev));
@@ -937,6 +931,12 @@ void __scsi_remove_device(struct scsi_device *sdev)
if (sdev->host->hostt->slave_destroy)
sdev->host->hostt->slave_destroy(sdev);
transport_destroy_device(dev);
+
+ /* cause the request function to reject all I/O requests */
+ sdev->request_queue->queuedata = NULL;
+
+ /* Freeing the queue signals to block that we're done */
+ scsi_free_queue(sdev->request_queue);
put_device(dev);
}