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Message-ID: <3CF2DCDE.CCBB499F@kegel.com>
Date: Mon, 27 May 2002 18:26:54 -0700
From: Dan Kegel <dank@kegel.com>
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To: Aaron Sethman <androsyn@ratbox.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        pwaechtler@loewe-komp.de, austin@digitalroadkill.net
Subject: Re: RT Sigio broken on 2.4.19-pre8
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Dan Kegel wrote:
> 
> Aaron Sethman wrote:
> > > > Using the Dan Kegel's Poller_bench utility I noticed that RT SIGIO is not
> > > > working on 2.4.19-pre8.  Basically sigtimedwait() is always returning
> > > > SIGIO.  Note that 2.4.18 works fine.
> > > > ... It seems rtsig-nr keeping rising slowly as the system runs.
> 
> That sounds like the way I'm clearing the signal queue is not working.
> Here's a minimal test case for clearing the signal queue.  Could
> you try it and tell me what it says?

Er, forgot to send the signal.  Corrected test case:

#include <stdio.h>
#include <signal.h>
#include <assert.h>

int main(int argc, char **argv)
{
    sigset_t sigset;
    siginfo_t info;
    static struct timespec timeout = {0,0};

    // block delivery of SIGRTMIN
    sigemptyset(&sigset);
    sigaddset(&sigset, SIGRTMIN);
    assert(0 == sigprocmask(SIG_BLOCK, &sigset, NULL));

    raise(SIGRTMIN);

    // clear signal queue
    assert(0 == signal(SIGRTMIN, SIG_IGN)); // POSIX says this clears the queue

    // Make sure that cleared the queue.  (Note that timeout is zero here.)
    assert(sigtimedwait(&sigset, &info, &timeout) != SIGRTMIN);

    printf("test passed\n");
    exit(0);
}