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From: Daniel Jacobowitz <dan@debian.org>
To: "Udo A. Steinberg" <us15@os.inf.tu-dresden.de>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: ptrace Issues
Date: Sat, 21 Jun 2003 15:55:31 -0400	[thread overview]
Message-ID: <20030621195531.GA25700@nevyn.them.org> (raw)
In-Reply-To: <20030509004759.46182eca.us15@os.inf.tu-dresden.de>

On Fri, May 09, 2003 at 12:47:59AM +0200, Udo A. Steinberg wrote:
> 
> Hi all,
> 
> I have discovered that recently I can no longer attach via strace to 
> already running processes for a long time. Specifically I have a daemon which
> sleeps in select and periodically wakes up from SIGALRM signals. As soon as a
> signal hits, strace quits on 2.5.69, however, it works fine on 2.4.21-rc.
> Can someone shed some light on what's going on?

Sorry it took so long...

> root@Corona:~> strace -p 527
> --- SIGSTOP (Stopped (signal)) ---
> --- SIGSTOP (Stopped (signal)) ---
> select(7, [0 3 6], [], NULL, NULL)      = ? ERESTARTNOHAND (To be restarted)
> --- SIGALRM (Alarm clock) ---
> root@Corona:~> echo $?
> 0

I can't explain why it works for you on 2.4.21-rc.  Were they the same
system and strace version?

The short answer appears to be: this is a bug in strace, not a bug in
the kernel.  If you get 4.4.98, it'll work.  There was an off-by-one
bug in parsing /proc/%d/status for the list of signals.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer

      reply	other threads:[~2003-06-21 19:41 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-05-08 22:47 ptrace Issues Udo A. Steinberg
2003-06-21 19:55 ` Daniel Jacobowitz [this message]

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