From 6f13ad1989875b5a0ce50b24211fd1fba093735f Mon Sep 17 00:00:00 2001 From: Jose Bollo Date: Fri, 2 Aug 2019 16:23:50 +0200 Subject: [PATCH] Avoid lock when child dies Interaction between pthread_cond_wait, pthread_broadcast and signal may lead to lock when the child of afb-daemon dies. To avoid that sad behavior, this commit defers the call to "job_exit" using lazy job queueing. Bug-AGL: SPEC-2720 Change-Id: Ifd1a56f4a439e1704f79a1291fa01f39b1640f29 Signed-off-by: Jose Bollo --- src/afb-session.c | 2 +- src/main-afb-daemon.c | 24 +++++++++++++++++------- 2 files changed, 18 insertions(+), 8 deletions(-) diff --git a/src/afb-session.c b/src/afb-session.c index 1bdb59db..61aa3f61 100644 --- a/src/afb-session.c +++ b/src/afb-session.c @@ -579,7 +579,7 @@ static int cookeyidx(const void *key) * @param makecb the creation function or NULL * @param freecb the release function or NULL * @param closure an argument for makecb or the value if makecb==NULL - * @param replace a boolean enforcing replecement of the previous value + * @param replace a boolean enforcing replacement of the previous value * * @return the value of the cookie * diff --git a/src/main-afb-daemon.c b/src/main-afb-daemon.c index 7b92905f..3421be81 100644 --- a/src/main-afb-daemon.c +++ b/src/main-afb-daemon.c @@ -403,15 +403,25 @@ static struct afb_hsrv *start_http_server() | execute_command +--------------------------------------------------------- */ -static void wait_child_and_exit() +static void exit_at_end() { + exit(0); +} + +static void wait_child(int signum, void* arg) +{ + pid_t pid = (pid_t)(intptr_t)arg; pid_t pidchld = childpid; - childpid = 0; - if (!SELF_PGROUP) - killpg(pidchld, SIGKILL); - waitpid(pidchld, NULL, 0); - exit(0); + if (pidchld == pid) { + childpid = 0; + if (!SELF_PGROUP) + killpg(pidchld, SIGKILL); + waitpid(pidchld, NULL, 0); + jobs_exit(exit_at_end); + } else { + waitpid(pid, NULL, 0); + } } static void on_sigchld(int signum, siginfo_t *info, void *uctx) @@ -421,7 +431,7 @@ static void on_sigchld(int signum, siginfo_t *info, void *uctx) case CLD_EXITED: case CLD_KILLED: case CLD_DUMPED: - jobs_exit(wait_child_and_exit); + jobs_queue_lazy(0, 0, wait_child, (void*)(intptr_t)info->si_pid); default: break; } -- 2.16.6