linux-kernel - Re: [PATCH] kernel/signal.c: Export symbol __lock_task

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Message-ID: <20200622062527.GA6516@redhat.com>
Date:   Mon, 22 Jun 2020 08:25:28 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Alexander Kapshuk <alexander.kapshuk@...il.com>
Cc:     linux-kernel@...r.kernel.org, christian.brauner@...ntu.com,
        ebiederm@...ssion.com, akpm@...ux-foundation.org,
        liuzhiqiang26@...wei.com, joel@...lfernandes.org,
        paulmck@...ux.vnet.ibm.com, asmadeus@...ewreck.org,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] kernel/signal.c: Export symbol __lock_task_sighand

On 06/21, Alexander Kapshuk wrote:
>
> Export symbol __lock_task_sighand, so it is accessible from code compiled
> as modules.
> This fixes the following modpost error:
> ERROR: modpost: "__lock_task_sighand" [net/9p/9pnet.ko] undefined!
>
> Where __lock_task_sighand is called via lock_task_sighand in net/9p/client.c
> See https://lore.kernel.org/lkml/20200620201456.14304-1-alexander.kapshuk@gmail.com/.

Why?

current->sighand is stable and can't go away. Unless "current" is exiting and
has already passed exit_notify(). So I don't think net/9p needs this helper.

However, the games with TIF_SIGPENDING doesn't look right in any case.

Oleg.