Hello, Linus.
Another fix for a really old bug. It only affects drain_workqueue()
which isn't used often and even then triggers only during a pretty
small race window, so it isn't too surprising that it stayed hidden
for so long. The fix is straight-forward and low-risk. Kudos to Li
Bin for reporting and fixing the bug.
Thanks.
The following changes since commit 692b48258dda7c302e777d7d5f4217244478f1f6:
workqueue: replace pool->manager_arb mutex with a flag (2017-10-10 07:13:57
-0700)
are available in the git repository at:
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git for-4.14-fixes
for you to fetch changes up to cef572ad9bd7f85035ba8272e5352040e8be0152:
workqueue: Fix NULL pointer dereference (2017-10-30 07:56:01 -0700)
----------------------------------------------------------------
Li Bin (1):
workqueue: Fix NULL pointer dereference
kernel/workqueue_internal.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/workqueue_internal.h b/kernel/workqueue_internal.h
index 8635417..29fa81f 100644
--- a/kernel/workqueue_internal.h
+++ b/kernel/workqueue_internal.h
@@ -9,6 +9,7 @@
#include <linux/workqueue.h>
#include <linux/kthread.h>
+#include <linux/preempt.h>
struct worker_pool;
@@ -59,7 +60,7 @@ struct worker {
*/
static inline struct worker *current_wq_worker(void)
{
- if (current->flags & PF_WQ_WORKER)
+ if (in_task() && (current->flags & PF_WQ_WORKER))
return kthread_data(current);
return NULL;
}
