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fs: dlm: fix race between test_bit() and queue_work() 

commit eef6ec9bf3 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@vger.kernel.org
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexander Aring 2022-08-15 15:43:14 -04:00 committed by Greg Kroah-Hartman
parent aa59ac81e8
commit 4b47e7521a
1 changed files with 4 additions and 2 deletions
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6
fs/dlm/ast.c
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@ -200,13 +200,13 @@ void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
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);
@ -288,7 +288,9 @@ 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);