On 9/8/21 12:18 PM, Hao Xu wrote: > Hi Jens, Pavel, > I have a question about _async_wake(), would there be cases like > this: > async_cancel/poll_remove interrupt > spin_lock_irq() > list del poll->wait_entry event happens but irq disabled > so interrupt delays > spin_unlock_irq() > generate cqe > async_wake() called and > generate cqe wake_up*() looks for queued callbacks under that same spin, so it won't find that cancelled entry and so won't call io_async_wake(). There might be other similar (or not) problematic cases, though. > If it exists, there may be multiple -ECANCELED cqes for one req, > we may do something like this to avoid it: > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 30d959416eba..7822b2f9e890 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -5023,9 +5023,12 @@ static int __io_async_wake(struct io_kiocb *req, struct io_poll_iocb *poll, > if (mask && !(mask & poll->events)) > return 0; > > - trace_io_uring_task_add(req->ctx, req->opcode, req->user_data, mask); > + if (list_empty(&poll->wait.entry)) > + return 0; > + else > + list_del_init(&poll->wait.entry); > > - list_del_init(&poll->wait.entry); > + trace_io_uring_task_add(req->ctx, req->opcode, req->user_data, mask); > > req->result = mask; > req->io_task_work.func = func; -- Pavel Begunkov
