child_cleanup: reap as many child processes as possible

Under load it's possible multiple child processes have been killed before
we start processing the SIGCHILD signal, leaving zombie processes behind
everytime we miss a process.
Reap as many processes as possible instead of assuming one handler
call = one process like we currently did.

Can be reproduced by running the following commands in parallel:
 - tcpdump -i lo -w /tmp/test -C 1 -z /usr/bin/true
 - iperf3 -s
 - iperf3 -c localhost

diff --git a/tcpdump.c b/tcpdump.c
index f092e161634e663ccff4aefdb44e61f25def2460..b0d3aa5bd6deb1de1edf579b8fbb4f5ac6494ada 100644 (file)
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -2836,7 +2836,7 @@ cleanup(int signo _U_)
 static void
 child_cleanup(int signo _U_)
 {
-  wait(NULL);
+  while (waitpid(-1, NULL, WNOHANG) >= 0);
 }
 #endif /* HAVE_FORK && HAVE_VFORK */