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io_uring: halt SQO submission on ctx exit

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io_sq_thread_finish() is called in io_ring_ctx_free(), so SQPOLL task is
potentially running submitting new requests. It's not a disaster because
of using a "try" variant of percpu_ref_get, but is far from nice.

Remove ctx from the sqd ctx list earlier, before cancellation loop, so
SQPOLL can't find it and so won't submit new requests.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-03-14 20:57:11 +00:00 committed by Jens Axboe
parent 09a6f4efaa
commit f6d54255f4
1 changed files with 8 additions and 0 deletions
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8
fs/io_uring.c
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@ -8564,6 +8564,14 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
io_unregister_personality(ctx, index);
mutex_unlock(&ctx->uring_lock);
/* prevent SQPOLL from submitting new requests */
if (ctx->sq_data) {
io_sq_thread_park(ctx->sq_data);
list_del_init(&ctx->sqd_list);
io_sqd_update_thread_idle(ctx->sq_data);
io_sq_thread_unpark(ctx->sq_data);
}
io_kill_timeouts(ctx, NULL, NULL);
io_poll_remove_all(ctx, NULL, NULL);