[sctp] retry locking in case of failure

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>

diff --git a/libknet/transport_sctp.c b/libknet/transport_sctp.c
index b35a213cf13a48ae0f3277b28789808318a67801..e26eecdf00739b5f33d1612a9fcb4a80f5b0b1a9 100644 (file)
--- a/libknet/transport_sctp.c
+++ b/libknet/transport_sctp.c
@@ -15,6 +15,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <stdlib.h>
+#include <assert.h>
 
 #include "compat.h"
 #include "host.h"
@@ -274,6 +275,32 @@ exit_error:
        return err;
 }
 
+static void _lock_sleep_relock(knet_handle_t knet_h)
+{
+       int i = 0;
+
+       /* Don't hold onto the lock while sleeping */
+       pthread_rwlock_unlock(&knet_h->global_rwlock);
+
+       while (i < 5) {
+               usleep(knet_h->threads_timer_res / 16);
+               if (!pthread_rwlock_rdlock(&knet_h->global_rwlock)) {
+                       /*
+                        * lock acquired, we can go out
+                        */
+                       return;
+               } else {
+                       log_debug(knet_h, KNET_SUB_TRANSP_SCTP, "Unable to get read lock!");
+                       i++;
+               }
+       }
+       /*
+        * time to crash! if we cannot re-acquire the lock
+        * there is no easy way out of this one
+        */
+       assert(0);
+}
+
 int sctp_transport_tx_sock_error(knet_handle_t knet_h, int sockfd, int recv_err, int recv_errno)
 {
        sctp_connect_link_info_t *connect_info = knet_h->knet_transport_fd_tracker[sockfd].data;
@@ -300,10 +327,7 @@ int sctp_transport_tx_sock_error(knet_handle_t knet_h, int sockfd, int recv_err,
 #ifdef DEBUG
                        log_debug(knet_h, KNET_SUB_TRANSP_SCTP, "Sock: %d is overloaded. Slowing TX down", sockfd);
 #endif
-                       /* Don't hold onto the lock while sleeping */
-                       pthread_rwlock_unlock(&knet_h->global_rwlock);
-                       usleep(knet_h->threads_timer_res / 16);
-                       pthread_rwlock_rdlock(&knet_h->global_rwlock);
+                       _lock_sleep_relock(knet_h);
                        return 1;
                }
                return -1;
@@ -406,10 +430,7 @@ int sctp_transport_rx_sock_error(knet_handle_t knet_h, int sockfd, int recv_err,
         * Under RX pressure we need to give time to IPC to pick up the message
         */
 
-       /* Don't hold onto the lock while sleeping */
-       pthread_rwlock_unlock(&knet_h->global_rwlock);
-       usleep(knet_h->threads_timer_res / 2);
-       pthread_rwlock_rdlock(&knet_h->global_rwlock);
+       _lock_sleep_relock(knet_h);
        return 0;
 }