From 86b61156743b7ebdc049450a6f88452890fd9a61 Mon Sep 17 00:00:00 2001
From: Jakub Hrozek <jhrozek@redhat.com>
Date: Mon, 13 Aug 2012 15:30:39 +0200
Subject: Use PTHREAD_MUTEX_ROBUST to avoid deadlock in the client

https://fedorahosted.org/sssd/ticket/1460
---
 src/sss_client/common.c | 96 +++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 90 insertions(+), 6 deletions(-)

(limited to 'src/sss_client')

diff --git a/src/sss_client/common.c b/src/sss_client/common.c
index 59eae3b1f..5b1751593 100644
--- a/src/sss_client/common.c
+++ b/src/sss_client/common.c
@@ -976,24 +976,108 @@ errno_t sss_strnlen(const char *str, size_t maxlen, size_t *len)
 }
 
 #if HAVE_PTHREAD
-static pthread_mutex_t sss_nss_mutex = PTHREAD_MUTEX_INITIALIZER;
-static pthread_mutex_t sss_pam_mutex = PTHREAD_MUTEX_INITIALIZER;
+typedef void (*sss_mutex_init)(void);
 
+struct sss_mutex {
+    pthread_mutex_t mtx;
+
+    pthread_once_t once;
+    sss_mutex_init init;
+};
+
+static void sss_nss_mt_init(void);
+static void sss_pam_mt_init(void);
+
+static struct sss_mutex sss_nss_mtx = { .mtx  = PTHREAD_MUTEX_INITIALIZER,
+                                        .once = PTHREAD_ONCE_INIT,
+                                        .init = sss_nss_mt_init };
+
+static struct sss_mutex sss_pam_mtx = { .mtx  = PTHREAD_MUTEX_INITIALIZER,
+                                        .once = PTHREAD_ONCE_INIT,
+                                        .init = sss_pam_mt_init };
+
+
+/* Wrappers for robust mutex support */
+static int sss_mutexattr_setrobust (pthread_mutexattr_t *attr)
+{
+#ifdef HAVE_PTHREAD_MUTEXATTR_SETROBUST
+    return pthread_mutexattr_setrobust(attr, PTHREAD_MUTEX_ROBUST);
+#elif  HAVE_PTHREAD_MUTEXATTR_SETROBUST_NP
+    return pthread_mutexattr_setrobust_np(attr, PTHREAD_MUTEX_ROBUST_NP);
+#else
+#warning Robust mutexes are not supported on this platform.
+    return 0;
+#endif
+}
+
+static int sss_mutex_consistent(pthread_mutex_t *mtx)
+{
+#ifdef HAVE_PTHREAD_MUTEX_CONSISTENT
+    return pthread_mutex_consistent(mtx);
+#elif HAVE_PTHREAD_MUTEX_CONSISTENT_NP
+    return pthread_mutex_consistent_np(mtx);
+#else
+#warning Robust mutexes are not supported on this platform.
+    return 0;
+#endif
+}
+
+/* Generic mutex init, lock, unlock functions */
+static void sss_mt_init(struct sss_mutex *m)
+{
+    pthread_mutexattr_t attr;
+
+    if (pthread_mutexattr_init(&attr) != 0) {
+        return;
+    }
+    if (sss_mutexattr_setrobust(&attr) != 0) {
+        return;
+    }
+
+    pthread_mutex_init(&m->mtx, &attr);
+    pthread_mutexattr_destroy(&attr);
+}
+
+static void sss_mt_lock(struct sss_mutex *m)
+{
+    pthread_once(&m->once, m->init);
+    if (pthread_mutex_lock(&m->mtx) == EOWNERDEAD) {
+        sss_cli_close_socket();
+        sss_mutex_consistent(&m->mtx);
+    }
+}
+
+static void sss_mt_unlock(struct sss_mutex *m)
+{
+    pthread_mutex_unlock(&m->mtx);
+}
+
+/* NSS mutex wrappers */
+static void sss_nss_mt_init(void)
+{
+    sss_mt_init(&sss_nss_mtx);
+}
 void sss_nss_lock(void)
 {
-    pthread_mutex_lock(&sss_nss_mutex);
+    sss_mt_lock(&sss_nss_mtx);
 }
 void sss_nss_unlock(void)
 {
-    pthread_mutex_unlock(&sss_nss_mutex);
+    sss_mt_unlock(&sss_nss_mtx);
+}
+
+/* NSS mutex wrappers */
+static void sss_pam_mt_init(void)
+{
+    sss_mt_init(&sss_pam_mtx);
 }
 void sss_pam_lock(void)
 {
-    pthread_mutex_lock(&sss_pam_mutex);
+    sss_mt_lock(&sss_pam_mtx);
 }
 void sss_pam_unlock(void)
 {
-    pthread_mutex_unlock(&sss_pam_mutex);
+    sss_mt_unlock(&sss_pam_mtx);
 }
 
 #else
-- 
cgit