diff options
| author | Hao Xu <haoxu@linux.alibaba.com> | 2021-09-11 22:40:52 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-09-13 04:27:47 +0300 |
| commit | 767a65e9f31789d80e41edd03a802314905e8fbf (patch) | |
| tree | efc0d0cf64e9e0b225c0c9435004b951381ea384 /fs/io-wq.c | |
| parent | 7a842fb589e3cdbe205bc16dc37c30cf13383159 (diff) | |
| download | linux-767a65e9f31789d80e41edd03a802314905e8fbf.tar.xz | |
io-wq: fix potential race of acct->nr_workers
Given max_worker is 1, and we currently have 1 running and it is
exiting. There may be race like:
io_wqe_enqueue worker1
no work there and timeout
unlock(wqe->lock)
->insert work
-->io_worker_exit
lock(wqe->lock)
->if(!nr_workers) //it's still 1
unlock(wqe->lock)
goto run_cancel
lock(wqe->lock)
nr_workers--
->dec_running
->worker creation fails
unlock(wqe->lock)
We enqueued one work but there is no workers, causes hung.
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io-wq.c')
| -rw-r--r-- | fs/io-wq.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/fs/io-wq.c b/fs/io-wq.c index a1685b40a4bf..3d4460df845c 100644 --- a/fs/io-wq.c +++ b/fs/io-wq.c @@ -176,7 +176,6 @@ static void io_worker_ref_put(struct io_wq *wq) static void io_worker_exit(struct io_worker *worker) { struct io_wqe *wqe = worker->wqe; - struct io_wqe_acct *acct = io_wqe_get_acct(worker); if (refcount_dec_and_test(&worker->ref)) complete(&worker->ref_done); @@ -186,7 +185,6 @@ static void io_worker_exit(struct io_worker *worker) if (worker->flags & IO_WORKER_F_FREE) hlist_nulls_del_rcu(&worker->nulls_node); list_del_rcu(&worker->all_list); - acct->nr_workers--; preempt_disable(); io_wqe_dec_running(worker); worker->flags = 0; @@ -569,6 +567,7 @@ loop: } /* timed out, exit unless we're the last worker */ if (last_timeout && acct->nr_workers > 1) { + acct->nr_workers--; raw_spin_unlock(&wqe->lock); __set_current_state(TASK_RUNNING); break; |