mdmon: recreate socket/pid file on SIGHUP

Allow mdmon to start while /var/run/mdadm is readonly.  Later a SIGHUP
can trigger mdmon to drop its pid and socket once /var/run/mdadm is
writable.  Of course one needs the pid to send a HUP, that can be stored
in a distribution specific rw-init directory... For now, rely on a
killall -HUP mdmon to get the files dumped.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/mdstat.c b/mdstat.c
index 00714b48..ebdfc67b 100644
--- a/mdstat.c
+++ b/mdstat.c
@@ -280,7 +280,8 @@ void mdstat_wait_fd(int fd, const sigset_t *sigmask)
 	FD_ZERO(&rfds);
 	if (mdstat_fd >= 0)
 		FD_SET(mdstat_fd, &fds);
-	FD_SET(fd, &rfds);
+	if (fd >= 0)
+		FD_SET(fd, &rfds);
 	if (mdstat_fd > maxfd)
 		maxfd = mdstat_fd;