linux-kernel - Re: [PATCH v3 4/7] linux/signal.h: Ignore SIGINFO by default in new tasks

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Message-ID: <780cb05e-a749-77a0-dabc-bd09982aa028@suse.cz>
Date:   Thu, 30 Apr 2020 08:53:56 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     Arseny Maslennikov <ar@...msu.ru>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Rob Landley <rob@...dley.net>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Pavel Machek <pavel@....cz>, linux-api@...r.kernel.org,
        "Vladimir D. Seleznev" <vseleznv@...linux.org>
Subject: Re: [PATCH v3 4/7] linux/signal.h: Ignore SIGINFO by default in new
 tasks

On 30. 04. 20, 8:42, Arseny Maslennikov wrote:
> This matches the behaviour of other Unix-like systems that have SIGINFO
> and causes less harm to processes that do not install handlers for this
> signal, making the keyboard status character non-fatal for them.
> 
> This is implemented with the assumption that SIGINFO is defined
> to be equivalent to SIGPWR; still, there is no reason for PWR to
> result in termination of the signal recipient anyway — it does not
> indicate there is a fatal problem with the recipient's execution
> context (like e.g. FPE/ILL do), and we have TERM/KILL for explicit
> termination requests.
> 
> To put it another way:
> The only scenario where system behaviour actually changes is when the
> signal recipient has default disposition for SIGPWR. If a process
> chose to interpret a SIGPWR as an incentive to cleanly terminate, it
> would supply its own handler — and this commit does not affect processes
> with non-default handlers.
> 
> Signed-off-by: Arseny Maslennikov <ar@...msu.ru>
> ---
>  include/linux/signal.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/signal.h b/include/linux/signal.h
> index 05bacd2ab..dc31da8fc 100644
> --- a/include/linux/signal.h
> +++ b/include/linux/signal.h
> @@ -369,7 +369,7 @@ extern bool unhandled_signal(struct task_struct *tsk, int sig);
>   *	|  SIGSYS/SIGUNUSED  |	coredump 	|
>   *	|  SIGSTKFLT         |	terminate	|
>   *	|  SIGWINCH          |	ignore   	|
> - *	|  SIGPWR            |	terminate	|
> + *	|  SIGPWR            |	ignore   	|

You need to update signal.7 too:
https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/man7/signal.7#n285

thanks,
-- 
js
suse labs