From 4b418105a73181eb59d2b83c6e788eaafd0e7caa Mon Sep 17 00:00:00 2001
From: Adrian Muzyka <adrian.muzyka@consult.red>
Date: Thu, 4 Jul 2024 10:21:04 +0000
Subject: [PATCH] sigchld_handler_service: Iterate over all service children

If more than one service child is killed,
the SIGCHLD signals can be coalesced, causing service
to miss worker exit and perform clean-up
---
 memcr.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/memcr.c b/memcr.c
index 08c5c84..5fbc6b8 100644
--- a/memcr.c
+++ b/memcr.c
@@ -915,7 +915,7 @@ static void clear_pid_on_worker_exit_non_blocking(pid_t worker)
 {
 	for (int i=0; i<CHECKPOINTED_PIDS_LIMIT; ++i) {
 		if (checkpoint_service_data[i].worker == worker) {
-			fprintf(stdout, "[+] Clearing pid: %d with worker: %d ...\n",
+			fprintf(stdout, "[+] Clearing pid: %d with worker: %d on worker exit ...\n",
 				checkpoint_service_data[i].pid, worker);
 			cleanup_pid(checkpoint_service_data[i].pid);
 			checkpoint_service_data[i].pid = PID_INVALID;
@@ -2248,12 +2248,13 @@ static void sigchld_handler_service(int sig, siginfo_t *sip, void *notused)
 {
 	int status;
 	int _errno;
+	pid_t pid;
 
 	_errno = errno;
-	if (sip->si_pid == waitpid(sip->si_pid, &status, WNOHANG)) {
-		fprintf(stdout, "[+] Worker %d exit.\n", sip->si_pid);
-		clear_pid_on_worker_exit_non_blocking(sip->si_pid);
+	while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
+		clear_pid_on_worker_exit_non_blocking(pid);
 	}
+
 	errno = _errno;
 }