From owner-freebsd-hackers  Mon Dec 21 11:52:51 1998
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Received: (from majordom@localhost)
          by hub.freebsd.org (8.8.8/8.8.8) id LAA13409
          for freebsd-hackers-outgoing; Mon, 21 Dec 1998 11:52:51 -0800 (PST)
          (envelope-from owner-freebsd-hackers@FreeBSD.ORG)
Received: from tornado.cisco.com (tornado.cisco.com [171.69.104.22])
          by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id LAA13389
          for <hackers@FreeBSD.ORG>; Mon, 21 Dec 1998 11:52:43 -0800 (PST)
          (envelope-from lching@cisco.com)
Received: from lching-pc.cisco.com (lching-pc.cisco.com [171.69.206.55]) by tornado.cisco.com (8.8.5-Cisco.1/8.6.5) with ESMTP id OAA00903; Mon, 21 Dec 1998 14:52:32 -0500 (EST)
Received: from cisco.com (localhost.cisco.com [127.0.0.1])
	by lching-pc.cisco.com (8.8.8/8.8.8) with ESMTP id OAA08528;
	Mon, 21 Dec 1998 14:53:21 -0500 (EST)
	(envelope-from lching@cisco.com)
Message-ID: <367EA731.BFAB48C3@cisco.com>
Date: Mon, 21 Dec 1998 14:53:21 -0500
From: Larry Ching <lching@cisco.com>
X-Mailer: Mozilla 4.04 [en] (X11; I; FreeBSD 2.2.6-RELEASE i386)
MIME-Version: 1.0
To: Daniel Eischen <eischen@vigrid.com>
CC: hackers@FreeBSD.ORG, lching@cisco.com
Subject: Re: pthreads question
References: <199812211933.OAA01713@pcnet1.pcnet.com>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: owner-freebsd-hackers@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG

Daniel Eischen wrote:

> Larry Ching wrote:
>
> > > A quick glance of the code shows that this is what happens only
> > > if the signal is blocked in the thread.  If the signal is unblocked,
> > > then the thread should return with EINTR.  Use sigprocmask(2) to
> > > unblock the signal in the thread that you want to interrupt.
> >
> > Thank you for your help above.  The thread in question was making acall
> > to pthread_sigmask(SIG_UNBLOCK,...) to unblock the signal I
> > was using in pthread_kill().  I changed this call to
> > sigprocmask(SIG_UNBLOCK, ...) with no effect.  The thread remains
> > blocked in the read() call and no EINTR error code is returned.
> >
> > Any suggestions as to where to look next???
>
> You haven't set the action for the signal to SIG_IGN, have you?

There is this code segment in the thread to be killed:

  struct sigaction sa;
  sigset_t setUser1;

  sa.sa_handler = SigUsr1Handler;
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = 0;
  sigaction(SIGUSR1, &sa, NULL);

  sigemptyset(&setUser1);
  sigaddset(&setUser1, SIGUSR1);
  sigprocmask(SIG_UNBLOCK, &setUser1, NULL);
  //pthread_sigmask(SIG_UNBLOCK, &setUser1, NULL);

where SigUsr1Handler is defined as:

void SigUsr1Handler(int signal)
{
}

My understanding is that this guarantees the action to not
be SIG_IGN.  I don't understand why this is not sufficient
for the read() call to be interrupted.

> Got a simple prgram to demonstrate the problem?

No, but I will attempt to create one.

Larry Ching
Cisco Systems
lching@cisco.com



To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message