mdmon: wait for previous mdmon to exit during takeover

[thirdparty/mdadm.git] / mdmon.c

diff --git a/mdmon.c b/mdmon.c
index 0955fcc54a888557436d13ba018f65157dec6339..ff985d291ee9045ede3daf68c1184af3ee0384eb 100644 (file)
--- a/mdmon.c
+++ b/mdmon.c
@@ -171,6 +171,7 @@ static void try_kill_monitor(pid_t pid, char *devname, int sock)
        int fd;
        int n;
        long fl;
+       int rv;
 
        /* first rule of survival... don't off yourself */
        if (pid == getpid())
@@ -201,9 +202,16 @@ static void try_kill_monitor(pid_t pid, char *devname, int sock)
        fl &= ~O_NONBLOCK;
        fcntl(sock, F_SETFL, fl);
        n = read(sock, buf, 100);
-       /* Ignore result, it is just the wait that
-        * matters
-        */
+
+       /* If there is I/O going on it might took some time to get to
+        * clean state. Wait for monitor to exit fully to avoid races.
+        * Ping it with SIGUSR1 in case that it is sleeping  */
+       for (n = 0; n < 25; n++) {
+               rv = kill(pid, SIGUSR1);
+               if (rv < 0)
+                       break;
+               usleep(200000);
+       }
 }
 
 void remove_pidfile(char *devname)