linux-kernel - Re: [PATCH -mm] coredump: format_corename: don't append .%pid if multi-threaded

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Message-ID: <cfd18e0f0807220521x5faea19bn1f545b23b84ead6a@mail.gmail.com>
Date:	Tue, 22 Jul 2008 14:21:20 +0200
From:	"Michael Kerrisk" <mtk.manpages@...glemail.com>
To:	"Oleg Nesterov" <oleg@...sign.ru>
Cc:	"Alan Cox" <alan@...rguk.ukuu.org.uk>,
	"Roland McGrath" <roland@...hat.com>, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, andi@...stfloor.org
Subject: Re: [PATCH -mm] coredump: format_corename: don't append .%pid if multi-threaded

On Tue, Jul 22, 2008 at 2:18 PM, Oleg Nesterov <oleg@...sign.ru> wrote:
> If the coredumping is multi-threaded, format_corename() appends .%pid
> to the corename. This was needed before the proper multi-thread core
> dump support, now all the threads in the mm go into a single unified
> core file.
>
> Remove this special case, it is not even documented and we have "%p"
> and core_uses_pid.

Hi Oleg,

I have not thought about this at any length, but one question that
jumps to mind: could this feature still be useful for LinuxThreads,
where each thread does indeed have a separate PID?

Cheers,

Michael

>
> Signed-off-by: Oleg Nesterov <oleg@...sign.ru>
>
> --- 26-rc2/fs/exec.c~FORMAT_CORENAME_NO_MT_PID  2008-07-22 15:42:15.000000000 +0400
> +++ 26-rc2/fs/exec.c    2008-07-22 15:46:04.000000000 +0400
> @@ -1373,7 +1373,7 @@ EXPORT_SYMBOL(set_binfmt);
>  * name into corename, which must have space for at least
>  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
>  */
> -static int format_corename(char *corename, int nr_threads, long signr)
> +static int format_corename(char *corename, long signr)
>  {
>        const char *pat_ptr = core_pattern;
>        int ispipe = (*pat_ptr == '|');
> @@ -1480,8 +1480,7 @@ static int format_corename(char *corenam
>         * If core_pattern does not include a %p (as is the default)
>         * and core_uses_pid is set, then .%pid will be appended to
>         * the filename. Do not do this for piped commands. */
> -       if (!ispipe && !pid_in_pattern
> -           && (core_uses_pid || nr_threads)) {
> +       if (!ispipe && !pid_in_pattern && core_uses_pid) {
>                rc = snprintf(out_ptr, out_end - out_ptr,
>                              ".%d", task_tgid_vnr(current));
>                if (rc > out_end - out_ptr)
> @@ -1745,7 +1744,7 @@ int do_coredump(long signr, int exit_cod
>         * uses lock_kernel()
>         */
>        lock_kernel();
> -       ispipe = format_corename(corename, retval, signr);
> +       ispipe = format_corename(corename, signr);
>        unlock_kernel();
>        /*
>         * Don't bother to check the RLIMIT_CORE value if core_pattern points
>
>



-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
man-pages online: http://www.kernel.org/doc/man-pages/online_pages.html
Found a bug? http://www.kernel.org/doc/man-pages/reporting_bugs.html
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