linux-kernel - Re: signalfd() not handling sigqueue() sigval data correctly

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Message-ID: <cfd18e0f0804092203s33f0ca5as92f47c4db0b0220f@mail.gmail.com>
Date:	Thu, 10 Apr 2008 07:03:18 +0200
From:	"Michael Kerrisk" <mtk.manpages@...glemail.com>
To:	"Davide Libenzi" <davidel@...ilserver.org>
Cc:	lkml <linux-kernel@...r.kernel.org>
Subject: Re: signalfd() not handling sigqueue() sigval data correctly

Hi Davide,

> > I was doing some playing about with signalfd(), and seem to have encountered a
> > bug: when a signalfd read() fetches data for a signal that was sent by
> > sigqueue(), the data accompanying the signal is not returned.  Instead
> > ssi_int/ssi_ptr is zero.
>
> Michael, can you give the patch below a spin? I tested it on my x86_64 box
> and seems to be working fine:
>
> Got signal 44
>   ssi_code= -1
>   ssi_pid = 6314
>   ssi_uid = 1000
>   ssi_int = 123
>   ssi_ptr = 7b

This works for me on x86-32.  Thanks Davide!

Cheers,

Michael

> ---
>  fs/signalfd.c |    7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> Index: linux-2.6.mod/fs/signalfd.c
> ===================================================================
> --- linux-2.6.mod.orig/fs/signalfd.c    2008-04-09 11:53:37.000000000 -0700
> +++ linux-2.6.mod/fs/signalfd.c 2008-04-09 12:05:46.000000000 -0700
> @@ -111,9 +111,14 @@
>                err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
>                err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
>                break;
> -       default: /* this is just in case for now ... */
> +       default:
> +               /*
> +                * This case catches also the signals queued by sigqueue().
> +                */
>                err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
>                err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
> +               err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
> +               err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
>                break;
>        }
>
>



-- 
Michael Kerrisk
Maintainer of the Linux man-pages project: http://www.kernel.org/doc/man-pages/
Want to report a man-pages bug? Look here:
http://www.kernel.org/doc/man-pages/reporting_bugs.html
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