diff options
| author | Jens Axboe <axboe@kernel.dk> | 2022-09-29 15:29:13 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-09-29 16:07:45 -0600 |
| commit | 46a525e199e4037516f7e498c18f065b09df32ac (patch) | |
| tree | 684cad58b89870c0f4050aaa05dd76315871658b /io_uring | |
| parent | b000145e9907809406d8164c3b2b8861d95aecd1 (diff) | |
| download | lwn-46a525e199e4037516f7e498c18f065b09df32ac.tar.gz lwn-46a525e199e4037516f7e498c18f065b09df32ac.zip | |
io_uring: don't gate task_work run on TIF_NOTIFY_SIGNAL
This isn't a reliable mechanism to tell if we have task_work pending, we
really should be looking at whether we have any items queued. This is
problematic if forward progress is gated on running said task_work. One
such example is reading from a pipe, where the write side has been closed
right before the read is started. The fput() of the file queues TWA_RESUME
task_work, and we need that task_work to be run before ->release() is
called for the pipe. If ->release() isn't called, then the read will sit
forever waiting on data that will never arise.
Fix this by io_run_task_work() so it checks if we have task_work pending
rather than rely on TIF_NOTIFY_SIGNAL for that. The latter obviously
doesn't work for task_work that is queued without TWA_SIGNAL.
Reported-by: Christiano Haesbaert <haesbaert@haesbaert.org>
Cc: stable@vger.kernel.org
Link: https://github.com/axboe/liburing/issues/665
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring')
| -rw-r--r-- | io_uring/io_uring.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h index 177bd55357d7..48ce2348c8c1 100644 --- a/io_uring/io_uring.h +++ b/io_uring/io_uring.h @@ -231,11 +231,11 @@ static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx) static inline int io_run_task_work(void) { - if (test_thread_flag(TIF_NOTIFY_SIGNAL)) { + if (task_work_pending(current)) { + if (test_thread_flag(TIF_NOTIFY_SIGNAL)) + clear_notify_signal(); __set_current_state(TASK_RUNNING); - clear_notify_signal(); - if (task_work_pending(current)) - task_work_run(); + task_work_run(); return 1; } |