This patch fixes a bug which may result race condition
between btrfs_start_workers() and worker_loop().
btrfs_start_workers() executed in a parent thread writes
on workers->worker and worker_loop() in a child thread
reads workers->worker. However, there is no synchronization
enforcing the order of two operations.
This patch makes btrfs_start_workers() writes workers->worker
before it starts a child thread with worker_loop() in order to
resolve possible race condition.
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -273,10 +273,10 @@
INIT_LIST_HEAD(&worker->worker_list);
spin_lock_init(&worker->lock);
atomic_set(&worker->num_pending, 0);
+ worker->workers = workers;
worker->task = kthread_run(worker_loop, worker,
"btrfs-%s-%d",
workers->name,
workers->num_workers + i);
- worker->workers = workers;
if (IS_ERR(worker->task)) {
kfree(worker);
ret = PTR_ERR(worker->task);
--
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