s3: Avoid starving locks when many processes die at the same time

In g_lock_unlock we have a little race between the process_exists and
messaging_send call: We only send to 5 waiters now, they all might have died
between us checking their existence and sending the message. This change makes
g_lock_lock retry at least once every minute.

diff --git a/source3/lib/g_lock.c b/source3/lib/g_lock.c
index 512c0680d9f00992defc58705dbfde4d4e5948c1..33ebe948038353b76116c78ad7ee54de073403d9 100644 (file)
--- a/source3/lib/g_lock.c
+++ b/source3/lib/g_lock.c
@@ -298,7 +298,6 @@ NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
        NTSTATUS status;
        bool retry = false;
        struct timeval timeout_end;
-       struct timeval timeout_remaining;
        struct timeval time_now;
 
        DEBUG(10, ("Trying to acquire lock %d for %s\n", (int)lock_type,
@@ -339,6 +338,7 @@ NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
                fd_set *r_fds = NULL;
                int max_fd = 0;
                int ret;
+               struct timeval select_timeout;
 
                status = g_lock_trylock(ctx, name, lock_type);
                if (NT_STATUS_IS_OK(status)) {
@@ -395,12 +395,10 @@ NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
                }
 #endif
 
-               time_now = timeval_current();
-               timeout_remaining = timeval_until(&time_now, &timeout_end);
+               select_timeout = timeval_set(60, 0);
 
                ret = sys_select(max_fd + 1, r_fds, NULL, NULL,
-                                &timeout_remaining);
-
+                                &select_timeout);
                if (ret == -1) {
                        if (errno != EINTR) {
                                DEBUG(1, ("error calling select: %s\n",
@@ -421,7 +419,7 @@ NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
                                break;
                        } else {
                                DEBUG(10, ("select returned 0 but timeout not "
-                                          "not expired: strange - retrying\n"));
+                                          "not expired, retrying\n"));
                        }
                } else if (ret != 1) {
                        DEBUG(1, ("invalid return code of select: %d\n", ret));