BUG/MAJOR: ssl: Fallback to private session cache if current lock mode is not supported.

Process shared mutex seems not supported on some OSs (FreeBSD).

This patch checks errors on mutex lock init to fallback
on a private session cache (per process cache) in error cases.
diff --git a/include/proto/shctx.h b/include/proto/shctx.h
index a84e4a6..e0c695d 100644
--- a/include/proto/shctx.h
+++ b/include/proto/shctx.h
@@ -28,6 +28,9 @@
 #define SHCTX_APPNAME "haproxy"
 #endif
 
+#define SHCTX_E_ALLOC_CACHE -1
+#define SHCTX_E_INIT_LOCK   -2
+
 /* Allocate shared memory context.
  * <size> is the number of allocated blocks into cache (default 128 bytes)
  * A block is large enough to contain a classic session (without client cert)
diff --git a/src/cfgparse.c b/src/cfgparse.c
index c4f092f..7176b59 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -6744,6 +6744,8 @@
 		 * remains NULL so that listeners can later detach.
 		 */
 		list_for_each_entry(bind_conf, &curproxy->conf.bind, by_fe) {
+			int alloc_ctx;
+
 			if (!bind_conf->is_ssl) {
 				if (bind_conf->default_ctx) {
 					Warning("Proxy '%s': A certificate was specified but SSL was not enabled on bind '%s' at [%s:%d] (use 'ssl').\n",
@@ -6758,10 +6760,18 @@
 				continue;
 			}
 
-			if (shared_context_init(global.tune.sslcachesize, (global.nbproc > 1) ? 1 : 0) < 0) {
-				Alert("Unable to allocate SSL session cache.\n");
-				cfgerr++;
-				continue;
+			alloc_ctx = shared_context_init(global.tune.sslcachesize, (global.nbproc > 1) ? 1 : 0);
+			if (alloc_ctx < 0) {
+				if (alloc_ctx == SHCTX_E_INIT_LOCK) {
+					Warning("Unable to init lock for the shared SSL session cache. Falling back to private cache.\n");
+					alloc_ctx = shared_context_init(global.tune.sslcachesize, 0);
+				}
+
+				if (alloc_ctx < 0) {
+					Alert("Unable to allocate SSL session cache.\n");
+					cfgerr++;
+					continue;
+				}
 			}
 
 			/* initialize all certificate contexts */
diff --git a/src/shctx.c b/src/shctx.c
index f259b9c..86e6056 100644
--- a/src/shctx.c
+++ b/src/shctx.c
@@ -532,19 +532,36 @@
 	                                      PROT_READ | PROT_WRITE, maptype | MAP_ANON, -1, 0);
 	if (!shctx || shctx == MAP_FAILED) {
 		shctx = NULL;
-		return -1;
+		return SHCTX_E_ALLOC_CACHE;
 	}
 
 #ifndef USE_PRIVATE_CACHE
+	if (maptype == MAP_SHARED) {
 #ifdef USE_SYSCALL_FUTEX
-	shctx->waiters = 0;
+		shctx->waiters = 0;
 #else
-	pthread_mutexattr_init(&attr);
-	pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
-	pthread_mutex_init(&shctx->mutex, &attr);
+		if (pthread_mutexattr_init(&attr)) {
+			munmap(shctx, sizeof(struct shared_context)+(size*sizeof(struct shared_block)));
+			shctx = NULL;
+			return SHCTX_E_INIT_LOCK;
+		}
+
+		if (pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED)) {
+			pthread_mutexattr_destroy(&attr);
+			munmap(shctx, sizeof(struct shared_context)+(size*sizeof(struct shared_block)));
+			shctx = NULL;
+			return SHCTX_E_INIT_LOCK;
+		}
+
+		if (pthread_mutex_init(&shctx->mutex, &attr)) {
+			pthread_mutexattr_destroy(&attr);
+			munmap(shctx, sizeof(struct shared_context)+(size*sizeof(struct shared_block)));
+			shctx = NULL;
+			return SHCTX_E_INIT_LOCK;
+		}
 #endif
-	if (maptype == MAP_SHARED)
 		use_shared_mem = 1;
+	}
 #endif
 
 	memset(&shctx->active.data.session.key, 0, sizeof(struct ebmb_node));