[multipathd] set the netlink uevent socket's rcv buf to 262,142

Doing so will help avoid dropping uevents during the time that the
listen pthread does not have a receive buffer posted.

Edward Goggin, EMC

diff --git a/libmultipath/uevent.c b/libmultipath/uevent.c
index 9113f14..3f078c5 100644 (file)
--- a/libmultipath/uevent.c
+++ b/libmultipath/uevent.c
@@ -49,6 +49,10 @@ int uevent_listen(int (*uev_trigger)(struct uevent *, void * trigger_data),
        int sock;
        struct sockaddr_nl snl;
        int retval;
+       int rcvbufsz = 128*1024;
+       int rcvsz = 0;
+       int rcvszsz = sizeof(rcvsz);
+       unsigned int *prcvszsz = (unsigned int *)&rcvszsz;
 
        memset(&snl, 0x00, sizeof(struct sockaddr_nl));
        snl.nl_family = AF_NETLINK;
@@ -61,6 +65,27 @@ int uevent_listen(int (*uev_trigger)(struct uevent *, void * trigger_data),
                return 1;
        }
 
+       /*
+        * try to avoid dropping uevents, even so, this is not a guarantee,
+        * but it does help to change the netlink uevent socket's
+        * receive buffer threshold from the default value of 106,496 to
+        * the maximum value of 262,142.
+        */
+       retval = setsockopt(sock, SOL_SOCKET, SO_RCVBUF, &rcvbufsz,
+                           sizeof(rcvbufsz));
+
+       if (retval < 0) {
+               condlog(0, "error setting receive buffer size for socket, exit\n");
+               exit(1);
+       }
+       retval = getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &rcvsz, prcvszsz);
+
+       if (retval < 0) {
+               condlog(0, "error setting receive buffer size for socket, exit\n");
+               exit(1);
+       }
+       condlog(3, "receive buffer size for socket is %u.\n", rcvsz);
+
        retval = bind(sock, (struct sockaddr *) &snl,
                      sizeof(struct sockaddr_nl));
        if (retval < 0) {