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Re: [commit+7.6] testsuite: Add more valgrind kills on cleanup
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: gdb-patches at sourceware dot org
- Date: Mon, 18 Mar 2013 06:38:44 +0100
- Subject: Re: [commit+7.6] testsuite: Add more valgrind kills on cleanup
- References: <20130317204746.GA18446@host2.jankratochvil.net>
On Sun, 17 Mar 2013 21:47:46 +0100, Jan Kratochvil wrote:
> As Tom asked off-list before this case was not caught by 'orphanripper'
> http://pkgs.fedoraproject.org/cgit/gdb.git/tree/gdb-orphanripper.c
> present in Fedora GDB as this tool got stale waiting on fd EOF with stuck
> valgrind had this fd open for writing. This was exactly the reason why
> I wrote 'orphanripper' and its SIGCHLD handling should have caught that, I do
> not yet understand why 'orphanripper' failed in this case.
I found a race that kernel reports Z (Zombie) state for a process but
'kill (child, 0)' still returns 0 at that moment. So the code parses
/proc/CHILD/stat now.
It is now unrelated to FSF GDB but it was discussed the 'orphanripper'
testsuite wrapper could be upstreamed.
Jan
diff --git a/gdb-orphanripper.c b/gdb-orphanripper.c
index f8e3f49..d79d93c 100644
--- a/gdb-orphanripper.c
+++ b/gdb-orphanripper.c
@@ -47,13 +47,10 @@
static const char *progname;
-static volatile int signal_chld_hit = 0;
static volatile pid_t child;
static void signal_chld (int signo)
{
- if (child && kill (child, 0) != 0)
- signal_chld_hit = 1;
}
static volatile int signal_alrm_hit = 0;
@@ -104,6 +101,44 @@ static int read_out (int amaster)
return 1;
}
+/* kill (child, 0) == 0 sometimes even when CHILD's state is already "Z". */
+
+static int child_exited (void)
+{
+ char buf[200];
+ int fd, i, retval;
+ ssize_t got;
+ char *state;
+
+ snprintf (buf, sizeof (buf), "/proc/%ld/stat", (long) child);
+ fd = open (buf, O_RDONLY);
+ if (fd == -1)
+ {
+ perror ("open (/proc/CHILD/stat)");
+ exit (EXIT_FAILURE);
+ }
+ got = read (fd, buf, sizeof(buf));
+ if (got <= 0)
+ {
+ perror ("read (/proc/CHILD/stat)");
+ exit (EXIT_FAILURE);
+ }
+ if (close (fd) != 0)
+ {
+ perror ("close (/proc/CHILD/stat)");
+ exit (EXIT_FAILURE);
+ }
+ i = sscanf (buf, "%*d%*s%ms", &state);
+ if (i != 1)
+ {
+ perror ("sscanf (/proc/CHILD/stat)");
+ exit (EXIT_FAILURE);
+ }
+ retval = strcmp (state, "Z") == 0;
+ free (state);
+ return retval;
+}
+
static int spawn (char **argv, int timeout)
{
pid_t child_got;
@@ -157,6 +192,11 @@ static int spawn (char **argv, int timeout)
assert (i == STDIN_FILENO);
#endif
+ i = sigemptyset (&set);
+ assert (i == 0);
+ i = sigprocmask (SIG_SETMASK, &set, NULL);
+ assert (i == 0);
+
/* Do not setpgrp(2) in the parent process as the process-group
is shared for the whole sh(1) pipeline we could be a part
of. The process-group is set according to PID of the first
@@ -206,7 +246,7 @@ static int spawn (char **argv, int timeout)
i = ppoll (&pollfd, 1, NULL, &set);
if (i == -1 && errno == EINTR)
{
- if (signal_chld_hit)
+ if (child_exited ())
break;
/* Non-CHILD child may have exited. */
continue;
@@ -230,7 +270,7 @@ static int spawn (char **argv, int timeout)
exit (EXIT_FAILURE);
}
/* Child exited? */
- if (signal_chld_hit)
+ if (child_exited ())
break;
}
@@ -279,12 +319,10 @@ static int spawn (char **argv, int timeout)
exit (EXIT_FAILURE);
}
- /* In the POLLHUP case we may not have seen SIGCHLD so far. */
+ /* Not used in fact. */
i = sigprocmask (SIG_SETMASK, &set, NULL);
assert (i == 0);
- assert (signal_chld_hit != 0);
-
/* Do not unset O_NONBLOCK as a stale child (the whole purpose of this
program) having open its output pty would block us in read_out. */
#if 0