netdev - Re: [PATCH] net: Do not break out of sk_stream_wait_memory() with TIF_NOTIFY

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Date: Tue, 24 Oct 2023 15:56:17 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Sascha Hauer <s.hauer@...gutronix.de>, netdev@...r.kernel.org
Cc: 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 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() ?


Thanks!

Paolo