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Message-ID: <8404022493c5ceda74807a3407e5a087425678e2.camel@redhat.com> Date: Thu, 26 Oct 2023 10:49:18 +0200 From: Paolo Abeni <pabeni@...hat.com> To: Sascha Hauer <s.hauer@...gutronix.de> Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Jens Axboe <axboe@...nel.dk>, kernel@...gutronix.de Subject: Re: [PATCH] net: Do not break out of sk_stream_wait_memory() with TIF_NOTIFY_SIGNAL On Thu, 2023-10-26 at 09:03 +0200, Sascha Hauer wrote: > On Tue, Oct 24, 2023 at 03:56:17PM +0200, Paolo Abeni wrote: > > On Mon, 2023-10-23 at 14:13 +0200, Sascha Hauer wrote: > > > It can happen that a socket sends the remaining data at close() time. > > > With io_uring and KTLS it can happen that sk_stream_wait_memory() bails > > > out with -512 (-ERESTARTSYS) because TIF_NOTIFY_SIGNAL is set for the > > > current task. This flag has been set in io_req_normal_work_add() by > > > calling task_work_add(). > > > > > > It seems signal_pending() is too broad, so this patch replaces it with > > > task_sigpending(), thus ignoring the TIF_NOTIFY_SIGNAL flag. > > > > This looks dangerous, at best. Other possible legit users setting > > TIF_NOTIFY_SIGNAL will be broken. > > > > Can't you instead clear TIF_NOTIFY_SIGNAL in io_run_task_work() ? > > I don't have an idea how io_run_task_work() comes into play here, but it > seems it already clears TIF_NOTIFY_SIGNAL: > > static inline int io_run_task_work(void) > { > /* > * Always check-and-clear the task_work notification signal. With how > * signaling works for task_work, we can find it set with nothing to > * run. We need to clear it for that case, like get_signal() does. > */ > if (test_thread_flag(TIF_NOTIFY_SIGNAL)) > clear_notify_signal(); > ... > } I see, io_run_task_work() is too late, sk_stream_wait_memory() is already woken up. I still think this patch is unsafe. What about explicitly handling the restart in tls_sw_release_resources_tx() ? The main point is that such function is called by inet_release() and the latter can't be re- started. Cheers, Paolo
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