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authorJens Axboe <axboe@kernel.dk>2020-08-06 19:41:50 -0600
committerJens Axboe <axboe@kernel.dk>2020-08-10 15:17:46 -0600
commit0ba9c9edcd152158a0e321a4c13ac1dfc571ff3d (patch)
tree550aaf132b452098435e9bf161214e682afed0f1 /fs/io_uring.c
parentf74441e6311a28f0ee89b9c8e296a33730f812fc (diff)
downloadlinux-0ba9c9edcd152158a0e321a4c13ac1dfc571ff3d.tar.bz2
io_uring: use TWA_SIGNAL for task_work uncondtionally
An earlier commit: b7db41c9e03b ("io_uring: fix regression with always ignoring signals in io_cqring_wait()") ensured that we didn't get stuck waiting for eventfd reads when it's registered with the io_uring ring for event notification, but we still have cases where the task can be waiting on other events in the kernel and need a bigger nudge to make forward progress. Or the task could be in the kernel and running, but on its way to blocking. This means that TWA_RESUME cannot reliably be used to ensure we make progress. Use TWA_SIGNAL unconditionally. Cc: stable@vger.kernel.org # v5.7+ Reported-by: Josef <josef.grieb@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
-rw-r--r--fs/io_uring.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index e9b27cdaa735..af6811ddcfbd 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1710,22 +1710,22 @@ static int io_req_task_work_add(struct io_kiocb *req, struct callback_head *cb)
{
struct task_struct *tsk = req->task;
struct io_ring_ctx *ctx = req->ctx;
- int ret, notify = TWA_RESUME;
+ int ret, notify;
/*
- * SQPOLL kernel thread doesn't need notification, just a wakeup.
- * If we're not using an eventfd, then TWA_RESUME is always fine,
- * as we won't have dependencies between request completions for
- * other kernel wait conditions.
+ * SQPOLL kernel thread doesn't need notification, just a wakeup. For
+ * all other cases, use TWA_SIGNAL unconditionally to ensure we're
+ * processing task_work. There's no reliable way to tell if TWA_RESUME
+ * will do the job.
*/
- if (ctx->flags & IORING_SETUP_SQPOLL)
- notify = 0;
- else if (ctx->cq_ev_fd)
+ notify = 0;
+ if (!(ctx->flags & IORING_SETUP_SQPOLL))
notify = TWA_SIGNAL;
ret = task_work_add(tsk, cb, notify);
if (!ret)
wake_up_process(tsk);
+
return ret;
}