This is a note to let you know that I've just added the patch titled
fs: dlm: fix race between test_bit() and queue_work()
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fs-dlm-fix-race-between-test_bit-and-queue_work.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From eef6ec9bf390e836a6c4029f3620fe49528aa1fe Mon Sep 17 00:00:00 2001
From: Alexander Aring <aahringo@xxxxxxxxxx>
Date: Mon, 15 Aug 2022 15:43:14 -0400
Subject: fs: dlm: fix race between test_bit() and queue_work()
From: Alexander Aring <aahringo@xxxxxxxxxx>
commit eef6ec9bf390e836a6c4029f3620fe49528aa1fe upstream.
This patch fixes a race by using ls_cb_mutex around the bit
operations and conditional code blocks for LSFL_CB_DELAY.
The function dlm_callback_stop() expects to stop all callbacks and
flush all currently queued onces. The set_bit() is not enough because
there can still be queue_work() after the workqueue was flushed.
To avoid queue_work() after set_bit(), surround both by ls_cb_mutex.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx>
Signed-off-by: David Teigland <teigland@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/dlm/ast.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/fs/dlm/ast.c
+++ b/fs/dlm/ast.c
@@ -198,13 +198,13 @@ void dlm_add_cb(struct dlm_lkb *lkb, uin
if (!prev_seq) {
kref_get(&lkb->lkb_ref);
+ mutex_lock(&ls->ls_cb_mutex);
if (test_bit(LSFL_CB_DELAY, &ls->ls_flags)) {
- mutex_lock(&ls->ls_cb_mutex);
list_add(&lkb->lkb_cb_list, &ls->ls_cb_delay);
- mutex_unlock(&ls->ls_cb_mutex);
} else {
queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
}
+ mutex_unlock(&ls->ls_cb_mutex);
}
out:
mutex_unlock(&lkb->lkb_cb_mutex);
@@ -284,7 +284,9 @@ void dlm_callback_stop(struct dlm_ls *ls
void dlm_callback_suspend(struct dlm_ls *ls)
{
+ mutex_lock(&ls->ls_cb_mutex);
set_bit(LSFL_CB_DELAY, &ls->ls_flags);
+ mutex_unlock(&ls->ls_cb_mutex);
if (ls->ls_callback_wq)
flush_workqueue(ls->ls_callback_wq);
Patches currently in stable-queue which might be from aahringo@xxxxxxxxxx are
queue-4.9/fs-dlm-handle-ebusy-first-in-lock-arg-validation.patch
queue-4.9/fs-dlm-fix-race-between-test_bit-and-queue_work.patch
