Re: [PATCH AUTOSEL 6.6 054/139] net: tls: wait for async completion on last message

[Jakub Kicinski <kuba@kernel.org>]

On Wed, 25 Sep 2024 08:07:54 -0400 Sasha Levin wrote:
> From: Sascha Hauer <s.hauer@pengutronix.de>
> 
> [ Upstream commit 54001d0f2fdbc7852136a00f3e6fc395a9547ae5 ]
> 
> When asynchronous encryption is used KTLS sends out the final data at
> proto->close time. This becomes problematic when the task calling
> close() receives a signal. In this case it can happen that
> tcp_sendmsg_locked() called at close time returns -ERESTARTSYS and the
> final data is not sent.
> 
> The described situation happens when KTLS is used in conjunction with
> io_uring, as io_uring uses task_work_add() to add work to the current
> userspace task. A discussion of the problem along with a reproducer can
> be found in [1] and [2]
> 
> Fix this by waiting for the asynchronous encryption to be completed on
> the final message. With this there is no data left to be sent at close
> time.

I wouldn't backport this, it may cause perf regressions.