From owner-freebsd-hackers@freebsd.org Sun Dec 11 22:23:32 2016 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9D8B8C720DB for ; Sun, 11 Dec 2016 22:23:32 +0000 (UTC) (envelope-from jilles@stack.nl) Received: from mailout.stack.nl (mailout05.stack.nl [IPv6:2001:610:1108:5010::202]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mailout.stack.nl", Issuer "CA Cert Signing Authority" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 546F711B3 for ; Sun, 11 Dec 2016 22:23:32 +0000 (UTC) (envelope-from jilles@stack.nl) Received: from snail.stack.nl (snail.stack.nl [IPv6:2001:610:1108:5010::131]) by mailout.stack.nl (Postfix) with ESMTP id F098D41F5; Sun, 11 Dec 2016 23:23:28 +0100 (CET) Received: by snail.stack.nl (Postfix, from userid 1677) id DFA3D28494; Sun, 11 Dec 2016 23:23:28 +0100 (CET) Date: Sun, 11 Dec 2016 23:23:28 +0100 From: Jilles Tjoelker To: Konstantin Belousov Cc: FreeBSD Hackers , Jonathan de Boyne Pollard , supervision@list.skarnet.org Subject: Re: NOTE_TRACK, EVFILT_PROC, kqueue, and subreapers Message-ID: <20161211222328.GC17315@stack.nl> References: <20161201174837.GR3428@protected.rcdrun.com> <20161201125438.15230317@mydesk.domain.cxm> <20161206104020.6b2ebb30@eto-mona.office.smartweb.sk> <20161206102637.1ddd152a@mydesk.domain.cxm> <20161207155638.4b2dd629@eto-mona.office.smartweb.sk> <630ace89-e29b-d0d3-9f15-110d8dc3de08@NTLWorld.com> <20161208132842.5d7940bd@eto-mona.office.smartweb.sk> <20161211124637.GA17315@stack.nl> <20161211175451.GV54029@kib.kiev.ua> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161211175451.GV54029@kib.kiev.ua> User-Agent: Mutt/1.5.21 (2010-09-15) X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 11 Dec 2016 22:23:32 -0000 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 #include +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