Date: Mon, 12 Jul 2010 00:08:43 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Garrett Cooper <yanegomi@gmail.com> Cc: hackers@freebsd.org Subject: Re: *sigpause hanging on 8.x+ Message-ID: <20100711210843.GQ2408@deviant.kiev.zoral.com.ua> In-Reply-To: <AANLkTikfxu3BjQE4nnNJ-VeNSDy9vhfXEhY1XQ4jWtY4@mail.gmail.com> References: <AANLkTikfxu3BjQE4nnNJ-VeNSDy9vhfXEhY1XQ4jWtY4@mail.gmail.com>
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On Sun, Jul 11, 2010 at 12:39:39PM -0700, Garrett Cooper wrote:
> So, long story short... I've basically ported the open posix testsuite
> to FreeBSD, and one of the tests tests out sigpause. Unfortunately the
> sucker hangs on my dev box at home.
>=20
> I've written a short testcase that demonstrates this. It prints out:
>=20
> $ ~/test_sigpause
> 0
>=20
> And proceeds to be unresponsive to signals (except SIGSTOP / SIGKILL,
> as expected).
>=20
> When I monkey around with libc's compat4.3 stuff a bit, this is what come=
s up:
>=20
> $ env LD_LIBRARY_PATH=3D$PWD:/usr/src/lib/libc/../libthr ~/test_sigpause
> 0
> before sigemptyset
> before _sigsuspend
>=20
> So it's getting stuck after calling _sigsuspend.
>=20
> I tried the same thing on a i386 8-STABLE VM and it hangs as well.
>=20
> I tried applying similar printfs in libthr but it's not hitting that
> code at all (it's now responding to SIGTERM though, which is
> interesting, but not too interesting to me).
>=20
> I also wrote similar code that exercised the functionality in
> sigsuspend, by calling sigprocmask beforehand, and it works.
>=20
> Thoughts?
>=20
> -Garrett
>=20
> Dev machine:
> FreeBSD bayonetta.local 9.0-CURRENT FreeBSD 9.0-CURRENT #1
> r206173:209901M: Sun Jul 11 04:18:42 PDT 2010
> root@:/usr/obj/usr/src/sys/BAYONETTA amd64
> VM:
> FreeBSD starr-bastion.localdomain 8.0-STABLE FreeBSD 8.0-STABLE #0
> r207913: Tue May 11 06:21:57 UTC 2010
> root@starr-bastion.localdomain:/usr/obj/usr/src/sys/GENERIC i386
>=20
> Index: compat-43/sigcompat.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> --- compat-43/sigcompat.c (revision 206173)
> +++ compat-43/sigcompat.c (working copy)
> @@ -36,6 +36,7 @@
> #include "namespace.h"
> #include <sys/param.h>
> #include <signal.h>
> +#include <stdio.h>
> #include <string.h>
> #include "un-namespace.h"
> #include "libc_private.h"
> @@ -102,7 +103,9 @@
> {
> sigset_t set;
>=20
> + printf("before sigemptyset\n");
> sigemptyset(&set);
> + printf("before _sigsuspend\n");
> set.__bits[0] =3D mask;
> return (_sigsuspend(&set));
> }
> @@ -111,10 +114,16 @@
> xsi_sigpause(int sig)
> {
> sigset_t set;
> + int rc;
>=20
> + printf("before sigemptyset\n");
> sigemptyset(&set);
> + printf("before sigaddset\n");
> sigaddset(&set, sig);
> - return (_sigsuspend(&set));
> + printf("before _sigsuspend\n");
> + rc =3D (_sigsuspend(&set));
> + printf("after _sigsuspend\n");
> + return rc;
> }
>=20
> int
>=20
> $ cat ~/test_sigpause.c
> #include <signal.h>
> #include <stdio.h>
>=20
> int
> main (void)
> {
> printf("0\n");
> fflush(stdout);
> (void) sigpause(1);
> return 0;
> }
> $ cat ~/test_sigsuspend.c
> #include <err.h>
> #include <signal.h>
>=20
> int
> main (void)
> {
> sigset_t oset;
> sigset_t nset;
> if (sigprocmask(1, &nset, &oset) =3D=3D -1)
> err(1, "sigprocmask(-1, &nset, &oset)");
> if (sigprocmask(-1, &nset, &oset) =3D=3D -1)
> err(1, "sigprocmask(-1, &nset, &oset)");
> return (sigsuspend(&nset));
> }
It seems I got a sigmask for sigpause inside the xsi_sigpause() backward.
On the other hand, I do not understand what is your issue with sigpause().
diff --git a/lib/libc/compat-43/sigcompat.c b/lib/libc/compat-43/sigcompat.c
index c3ba30a..bab9d5c 100644
--- a/lib/libc/compat-43/sigcompat.c
+++ b/lib/libc/compat-43/sigcompat.c
@@ -111,9 +111,12 @@ int
xsi_sigpause(int sig)
{
sigset_t set;
+ int error;
=20
- sigemptyset(&set);
- sigaddset(&set, sig);
+ error =3D _sigprocmask(SIG_BLOCK, NULL, &set);
+ if (error !=3D 0)
+ return (error);
+ sigdelset(&set, sig);
return (_sigsuspend(&set));
}
=20
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