Add retry when bring up the network interface

During SW reset, the network interface could still be busy. This
commit adds a robust retry when the returning code is EBUSY.

Signed-off-by: Liming Sun <lsun@mellanox.com>

Author: lsun100

src/rshim.c

@@ -3187,10 +3187,9 @@ int rshim_register(rshim_backend_t *bd)
          sizeof(init_console_termios));
 
   bd->index = index;
-  if (rshim_dev_names[index] != bd->dev_name) {
+  if (rshim_dev_names[index])
     free(rshim_dev_names[index]);
-    rshim_dev_names[index] = bd->dev_name;
-  }
+  rshim_dev_names[index] = strdup(bd->dev_name);
   rshim_devs[index] = bd;
 
   for (i = 0; i < 2; i++) {

src/rshim_net.c

@@ -51,7 +51,7 @@ static int rshim_if_open(char *ifname, int index)
 {
   char cmd[128];
   struct ifreq ifr;
-  int s, fd, rc;
+  int s, fd, rc, retry;
 
   rc = system("modprobe tun");
   if (rc == -1)
@@ -67,8 +67,14 @@ static int rshim_if_open(char *ifname, int index)
   ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
   strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
 
-  if (ioctl(fd, TUNSETIFF, (void *) &ifr) < 0) {
-    RSHIM_ERR("ioctl failed: %m\n");
+  retry = 16;
+  do {
+    rc = ioctl(fd, TUNSETIFF, (void *) &ifr);
+    if (rc == -1 && retry)
+      sleep(1);
+  } while (rc == -1 && errno == EBUSY && retry--);
+  if (rc < 0) {
+    RSHIM_ERR("ioctl failed: %m, errno=%d\n", errno);
     close(fd);
     return -1;
   }