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authorHao Xu <haoxu@linux.alibaba.com>2021-09-12 03:40:52 +0800
committerJens Axboe <axboe@kernel.dk>2021-09-12 19:27:47 -0600
commit767a65e9f31789d80e41edd03a802314905e8fbf (patch)
treeefc0d0cf64e9e0b225c0c9435004b951381ea384 /fs
parent7a842fb589e3cdbe205bc16dc37c30cf13383159 (diff)
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')
-rw-r--r--fs/io-wq.c3
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;