linux-kernel - Re: [PATCH AUTOSEL 6.14 26/31] um: Rewrite the sigio workaround based on epoll and tgkill

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Message-ID: <ab2a3e64-b8ef-4e27-9d73-3b08b4364528@antgroup.com>
Date: Tue, 08 Apr 2025 12:36:17 +0800
From: "Tiwei Bie" <tiwei.btw@...group.com>
To: Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Cc: Johannes Berg <johannes.berg@...el.com>, richard@....at,
 anton.ivanov@...bridgegreys.com, johannes@...solutions.net,
 benjamin.berg@...el.com, linux-um@...ts.infradead.org
Subject: Re: [PATCH AUTOSEL 6.14 26/31] um: Rewrite the sigio workaround based
 on epoll and tgkill

On 2025/4/8 02:10, Sasha Levin wrote:
> From: Tiwei Bie <tiwei.btw@...group.com>
> 
> [ Upstream commit 33c9da5dfb18c2ff5a88d01aca2cf253cd0ac3bc ]
> 
> The existing sigio workaround implementation removes FDs from the
> poll when events are triggered, requiring users to re-add them via
> add_sigio_fd() after processing. This introduces a potential race
> condition between FD removal in write_sigio_thread() and next_poll
> update in __add_sigio_fd(), and is inefficient due to frequent FD
> removal and re-addition. Rewrite the implementation based on epoll
> and tgkill for improved efficiency and reliability.
> 
> Signed-off-by: Tiwei Bie <tiwei.btw@...group.com>
> Link: https://patch.msgid.link/20250315161910.4082396-2-tiwei.btw@antgroup.com
> Signed-off-by: Johannes Berg <johannes.berg@...el.com>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  arch/um/drivers/random.c       |   2 +-
>  arch/um/drivers/rtc_user.c     |   2 +-
>  arch/um/include/shared/os.h    |   2 +-
>  arch/um/include/shared/sigio.h |   1 -
>  arch/um/kernel/sigio.c         |  26 ---
>  arch/um/os-Linux/sigio.c       | 330 +++++----------------------------
>  6 files changed, 47 insertions(+), 316 deletions(-)

Please drop this patch. Thanks! Details can be found here: 

https://lore.kernel.org/linux-um/ffa0b6af-523d-4e3e-9952-92f5b04b82b3@antgroup.com/

Regards,
Tiwei