NOTE_TRACK, EVFILT_PROC, kqueue, and subreapers
Jilles Tjoelker
jilles at stack.nl
Sun Dec 11 22:23:32 UTC 2016
On Sun, Dec 11, 2016 at 07:54:51PM +0200, Konstantin Belousov wrote:
> On Sun, Dec 11, 2016 at 01:46:38PM +0100, Jilles Tjoelker wrote:
> > As reported in https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=213928
> > reapers do not receive SIGCHLD when inheriting zombies, although they do
> > receive SIGCHLD when an inherited descendant process later terminates
> > and are awakened when in a wait call for a matching process. This should
> > probably be fixed.
> I agree, in principle. Could you update your tests/sys/kern/reaper.c to
> include this scenario ?
I tested with the patch below. The new test case
reaper_sigchld_child_first already passes and I have marked
reaper_sigchld_grandchild_first as an expected timeout.
> Untested change to the kernel side is below.
> diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
> index f4f453c3556..92899740eef 100644
> --- a/sys/kern/kern_exit.c
> +++ b/sys/kern/kern_exit.c
> @@ -455,6 +455,12 @@ exit1(struct thread *td, int rval, int signo)
>
> if (!(q->p_flag & P_TRACED)) {
> proc_reparent(q, q->p_reaper);
> + if (q->p_state == PRS_ZOMBIE) {
> + PROC_LOCK(q->p_reaper);
> + pksignal(q->p_reaper, SIGCHLD, q->p_ksi);
> + wakeup(q->p_reaper);
> + PROC_UNLOCK(q->p_reaper);
> + }
> } else {
> /*
> * Traced processes are killed since their existence
This change makes reaper_sigchld_grandchild_first pass.
The wakeup added here is redundant with the one a few lines above:
if (q != NULL) /* only need this if any child is S_ZOMB */
wakeup(q->p_reaper);
This is also clear because reaper_wait_grandchild_first already passes.
Index: tests/sys/kern/reaper.c
===================================================================
--- tests/sys/kern/reaper.c (revision 309839)
+++ tests/sys/kern/reaper.c (working copy)
@@ -35,6 +35,11 @@
#include <signal.h>
#include <unistd.h>
+static void
+dummy_sighandler(int sig __unused, siginfo_t *info __unused, void *ctx __unused)
+{
+}
+
ATF_TC_WITHOUT_HEAD(reaper_wait_child_first);
ATF_TC_BODY(reaper_wait_child_first, tc)
{
@@ -129,6 +134,163 @@
ATF_CHECK_EQ(2, r);
}
+ATF_TC(reaper_sigchld_child_first);
+ATF_TC_HEAD(reaper_sigchld_child_first, tc)
+{
+ atf_tc_set_md_var(tc, "timeout", "2");
+}
+ATF_TC_BODY(reaper_sigchld_child_first, tc)
+{
+ struct sigaction act;
+ sigset_t mask;
+ siginfo_t info;
+ pid_t parent, child, grandchild, pid;
+ int r;
+ int pip[2];
+
+ /* Be paranoid. */
+ pid = waitpid(-1, NULL, WNOHANG);
+ ATF_REQUIRE(pid == -1 && errno == ECHILD);
+
+ act.sa_sigaction = dummy_sighandler;
+ act.sa_flags = SA_SIGINFO | SA_RESTART;
+ r = sigemptyset(&act.sa_mask);
+ ATF_REQUIRE_EQ(0, r);
+ r = sigaction(SIGCHLD, &act, NULL);
+ ATF_REQUIRE_EQ(0, r);
+
+ r = sigemptyset(&mask);
+ ATF_REQUIRE_EQ(0, r);
+ r = sigaddset(&mask, SIGCHLD);
+ ATF_REQUIRE_EQ(0, r);
+ r = sigprocmask(SIG_BLOCK, &mask, NULL);
+ ATF_REQUIRE_EQ(0, r);
+
+ parent = getpid();
+ r = procctl(P_PID, parent, PROC_REAP_ACQUIRE, NULL);
+ ATF_REQUIRE_EQ(0, r);
+
+ r = pipe(pip);
+ ATF_REQUIRE_EQ(0, r);
+
+ child = fork();
+ ATF_REQUIRE(child != -1);
+ if (child == 0) {
+ if (close(pip[1]) != 0)
+ _exit(100);
+ grandchild = fork();
+ if (grandchild == -1)
+ _exit(101);
+ else if (grandchild == 0) {
+ if (read(pip[0], &(uint8_t){ 0 }, 1) != 0)
+ _exit(102);
+ if (getppid() != parent)
+ _exit(103);
+ _exit(2);
+ } else
+ _exit(3);
+ }
+
+ r = sigwaitinfo(&mask, &info);
+ ATF_REQUIRE_EQ(SIGCHLD, r);
+ ATF_CHECK_EQ(SIGCHLD, info.si_signo);
+ ATF_CHECK_EQ(CLD_EXITED, info.si_code);
+ ATF_CHECK_EQ(3, info.si_status);
+ ATF_CHECK_EQ(child, info.si_pid);
+
+ pid = waitpid(child, NULL, 0);
+ ATF_REQUIRE_EQ(child, pid);
+
+ r = close(pip[1]);
+ ATF_REQUIRE_EQ(0, r);
+
+ r = sigwaitinfo(&mask, &info);
+ ATF_REQUIRE_EQ(SIGCHLD, r);
+ ATF_CHECK_EQ(SIGCHLD, info.si_signo);
+ ATF_CHECK_EQ(CLD_EXITED, info.si_code);
+ ATF_CHECK_EQ(2, info.si_status);
+ grandchild = info.si_pid;
+ ATF_REQUIRE(grandchild > 0);
+ ATF_REQUIRE(grandchild != parent);
+ ATF_REQUIRE(grandchild != child);
+
+ pid = waitpid(-1, NULL, 0);
+ ATF_REQUIRE_EQ(grandchild, pid);
+
+ r = close(pip[0]);
+ ATF_REQUIRE_EQ(0, r);
+}
+
+ATF_TC(reaper_sigchld_grandchild_first);
+ATF_TC_HEAD(reaper_sigchld_grandchild_first, tc)
+{
+ atf_tc_set_md_var(tc, "timeout", "2");
+}
+ATF_TC_BODY(reaper_sigchld_grandchild_first, tc)
+{
+ struct sigaction act;
+ sigset_t mask;
+ siginfo_t info;
+ pid_t parent, child, grandchild, pid;
+ int r;
+
+ atf_tc_expect_timeout("bug 213928");
+
+ /* Be paranoid. */
+ pid = waitpid(-1, NULL, WNOHANG);
+ ATF_REQUIRE(pid == -1 && errno == ECHILD);
+
+ act.sa_sigaction = dummy_sighandler;
+ act.sa_flags = SA_SIGINFO | SA_RESTART;
+ r = sigemptyset(&act.sa_mask);
+ ATF_REQUIRE_EQ(0, r);
+ r = sigaction(SIGCHLD, &act, NULL);
+ ATF_REQUIRE_EQ(0, r);
+
+ r = sigemptyset(&mask);
+ ATF_REQUIRE_EQ(0, r);
+ r = sigaddset(&mask, SIGCHLD);
+ ATF_REQUIRE_EQ(0, r);
+ r = sigprocmask(SIG_BLOCK, &mask, NULL);
+ ATF_REQUIRE_EQ(0, r);
+
+ parent = getpid();
+ r = procctl(P_PID, parent, PROC_REAP_ACQUIRE, NULL);
+ ATF_REQUIRE_EQ(0, r);
+
+ child = fork();
+ ATF_REQUIRE(child != -1);
+ if (child == 0) {
+ grandchild = fork();
+ if (grandchild == -1)
+ _exit(101);
+ else if (grandchild == 0)
+ _exit(2);
+ else {
+ if (waitid(P_PID, grandchild, NULL,
+ WNOWAIT | WEXITED) != 0)
+ _exit(102);
+ _exit(3);
+ }
+ }
+
+ pid = waitpid(child, NULL, 0);
+ ATF_REQUIRE_EQ(child, pid);
+
+ r = sigwaitinfo(&mask, &info);
+ ATF_REQUIRE_EQ(SIGCHLD, r);
+ ATF_CHECK_EQ(SIGCHLD, info.si_signo);
+ ATF_CHECK_EQ(CLD_EXITED, info.si_code);
+ ATF_CHECK_EQ(2, info.si_status);
+ grandchild = info.si_pid;
+ ATF_REQUIRE(grandchild > 0);
+ ATF_REQUIRE(grandchild != parent);
+ ATF_REQUIRE(grandchild != child);
+
+ pid = waitpid(-1, NULL, 0);
+ ATF_REQUIRE_EQ(grandchild, pid);
+}
+
ATF_TC_WITHOUT_HEAD(reaper_status);
ATF_TC_BODY(reaper_status, tc)
{
@@ -484,6 +646,8 @@
ATF_TP_ADD_TC(tp, reaper_wait_child_first);
ATF_TP_ADD_TC(tp, reaper_wait_grandchild_first);
+ ATF_TP_ADD_TC(tp, reaper_sigchld_child_first);
+ ATF_TP_ADD_TC(tp, reaper_sigchld_grandchild_first);
ATF_TP_ADD_TC(tp, reaper_status);
ATF_TP_ADD_TC(tp, reaper_getpids);
ATF_TP_ADD_TC(tp, reaper_kill_badsig);
--
Jilles Tjoelker
More information about the freebsd-hackers
mailing list