This is a note to let you know that I've just added the patch titled
[SCSI] put stricter guards on queue dead checks
to the 2.6.32-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.32.git;a=summary
The filename of the patch is:
put-stricter-guards-on-queue-dead-checks.patch
and it can be found in the queue-2.6.32 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.32 longterm
tree,
please let <[email protected]> know about it.
>From 86cbfb5607d4b81b1a993ff689bbd2addd5d3a9b Mon Sep 17 00:00:00 2001
From: James Bottomley <[email protected]>
Date: Fri, 22 Apr 2011 10:39:59 -0500
Subject: [SCSI] put stricter guards on queue dead checks
From: James Bottomley <[email protected]>
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 <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/scsi/scsi_sysfs.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -318,14 +318,8 @@ static void scsi_device_dev_release_user
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));
@@ -925,6 +919,12 @@ void __scsi_remove_device(struct scsi_de
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);
}
Patches currently in longterm-queue-2.6.32 which might be from
[email protected] are
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/slub-fix-panic-with-discontigmem.patch
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/pmcraid-reject-negative-request-size.patch
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/mpt2sas-prevent-heap-overflows-and-unchecked-reads.patch
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/put-stricter-guards-on-queue-dead-checks.patch
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/set-memory-ranges-in-n_normal_memory-when-onlined.patch
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