gssd: Don't wait for pthread_joinspthreads

To make gssd almost bullet proof from hanging
threads in the krb5 libs, only wait a second
for the thread to terminate.

If the termination takes longer add the th
id to a global and set an timeout. When
the timeout pops do the join again. If
the thread has still not terminate, set
another timeout. Continue this loop until
the thread terminates.

Signed-off-by: Steve Dickson <steved@redhat.com>

1 files changed, 81 insertions, 0 deletions

diff --git a/utils/gssd/gssd.c b/utils/gssd/gssd.c
index 844a7ae..0f76a88 100644
--- a/utils/gssd/gssd.c
+++ b/utils/gssd/gssd.c
@@ -362,8 +362,81 @@ gssd_destroy_client(struct clnt_info *clp)
 
 static void gssd_scan(void);
 
+static inline void gssd_sig_hold(int sig, sigset_t *mask)
+{
+	sigemptyset(mask);
+	sigaddset(mask, sig);
+	pthread_sigmask(SIG_BLOCK, mask, NULL);
+}
+static inline void gssd_sig_rel(sigset_t *mask)
+{
+	pthread_sigmask(SIG_UNBLOCK, mask, NULL);
+}
+
 #define JOIN_TIMOUT 1
+#define JOIN_ALARM 5
+
+#define TH_TBL_SZ 50
+TAILQ_HEAD(thread_list_head, threads) thread_list;
+struct threads {
+	TAILQ_ENTRY(threads) list;
+	pthread_t th;
+};
+struct threads th_tbl[TH_TBL_SZ];
+static inline void th_tbl_init(void);
+
+static inline void th_tbl_init()
+{
+	int i;
+	for (i = 0; i < TH_TBL_SZ; i++)
+		th_tbl[i].th = 0;
+}
+
+static void
+th_tbl_alarm(int signal)
+{
+	struct threads *thp;
+	int setalarm = 0;
+
+	printerr(2, "th_tbl_alarm signal %d\n", signal);
 
+	TAILQ_FOREACH(thp, &thread_list, list) {
+		if (pthread_tryjoin_np(thp->th, NULL) == 0) {
+			printerr(2, "th_tbl_alarm found 0x%x\n", thp->th);
+			thp->th = 0;
+		} else
+			setalarm++;
+	}
+	if (setalarm)
+		alarm(JOIN_ALARM);
+		
+}
+
+static int th_tbl_insert(pthread_t th)
+{
+	int i;
+	int status = 0;
+	sigset_t mask;
+
+	/* hold off any pending alarms */
+	gssd_sig_hold(SIGALRM, &mask);
+
+	for (i=0; i < TH_TBL_SZ; i++) {
+		if (th_tbl[i].th == 0) { /* free slot */
+			th_tbl[i].th = th;
+			TAILQ_INSERT_HEAD(&thread_list, &th_tbl[i], list);
+			status = 1;
+			printerr(2, "th_tbl_alarm set 0x%x\n", th);
+			break;
+		}
+	}
+	gssd_sig_rel(&mask);
+
+	if (status)
+		alarm(JOIN_ALARM);
+
+	return status;
+}
 /*
  * Try to join a terminated thread after a short wait.
  * If successful return 0 otherwise return 1 which 
@@ -381,6 +454,9 @@ static int gssd_try_join(pthread_t th)
 	if (pthread_timedjoin_np(th, NULL,  &ts) == 0)
 		return 0;
 
+	if (th_tbl_insert(th))
+		return 0;
+
 	printerr(2, "gssd_try_join: no join\n");
 	return 1;
 }
@@ -396,6 +472,7 @@ gssd_clnt_gssd_cb(int UNUSED(fd), short UNUSED(which), void *data)
 		printerr(0, "pthread_create failed: ret %d: %s\n", ret, strerror(errno)); 
 		return;
 	}
+
 	if (gssd_try_join(th))
 		pthread_join(th, NULL);
 }
@@ -946,6 +1023,7 @@ main(int argc, char *argv[])
 		exit(EXIT_FAILURE);
 	}
 
+	signal(SIGALRM, th_tbl_alarm);
 	signal(SIGINT, sig_die);
 	signal(SIGTERM, sig_die);
 	signal_set(&sighup_ev, SIGHUP, gssd_scan_cb, NULL);
@@ -953,6 +1031,9 @@ main(int argc, char *argv[])
 	event_set(&inotify_ev, inotify_fd, EV_READ | EV_PERSIST, gssd_inotify_cb, NULL);
 	event_add(&inotify_ev, NULL);
 
+	th_tbl_init();
+	TAILQ_INIT(&thread_list);
+
 	TAILQ_INIT(&topdir_list);
 	gssd_scan();
 	daemon_ready();