X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust-comm%2Flttng-ust-fd-tracker.c;h=42c3984cc2d3a390f941005f82a0315aa329c208;hb=48a143c09cc97bf7a2ace811277e7d60b294b5f6;hp=1118163a201af456ac6ed28d490e09f458af08ef;hpb=283f4bec47781f7a39dde82d02e53add02155f9c;p=lttng-ust.git

diff --git a/liblttng-ust-comm/lttng-ust-fd-tracker.c b/liblttng-ust-comm/lttng-ust-fd-tracker.c
index 1118163a..42c3984c 100644
--- a/liblttng-ust-comm/lttng-ust-fd-tracker.c
+++ b/liblttng-ust-comm/lttng-ust-fd-tracker.c
@@ -32,6 +32,8 @@
 #include <sys/time.h>
 #include <fcntl.h>
 #include <pthread.h>
+#include <signal.h>
+#include <stdbool.h>
 #include <urcu/compiler.h>
 #include <urcu/tls-compat.h>
 #include <urcu/system.h>
@@ -75,10 +77,20 @@ static int ust_safe_guard_saved_cancelstate;
 
 /*
  * Track whether we are within lttng-ust or application, for close
- * system call override by LD_PRELOAD library.
+ * system call override by LD_PRELOAD library. Threads registered
+ * as being lttng-ust listener threads need to perform fd tracker
+ * locking explicitly around their use of file descriptor manipulation
+ * functions.
  */
 static DEFINE_URCU_TLS(int, thread_fd_tracking);
 
+/*
+ * Track whether we are invoking close() from a signal handler nested on
+ * an application thread.
+ */
+static DEFINE_URCU_TLS(int, ust_fd_mutex_nest);
+
+
 /* fd_set used to book keep fd being used by lttng-ust. */
 static fd_set *lttng_fd_set;
 static int lttng_ust_max_fd;
@@ -91,6 +103,7 @@ static int init_done;
 void lttng_ust_fixup_fd_tracker_tls(void)
 {
 	asm volatile ("" : : "m" (URCU_TLS(thread_fd_tracking)));
+	asm volatile ("" : : "m" (URCU_TLS(ust_fd_mutex_nest)));
 }
 
 /*
@@ -134,37 +147,63 @@ void lttng_ust_init_fd_tracker(void)
 
 void lttng_ust_lock_fd_tracker(void)
 {
+	sigset_t sig_all_blocked, orig_mask;
 	int ret, oldstate;
 
 	ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
 	if (ret) {
 		ERR("pthread_setcancelstate: %s", strerror(ret));
 	}
-	URCU_TLS(thread_fd_tracking) = 1;
-	/*
-	 * Ensure the compiler don't move the store after the close()
-	 * call in case close() would be marked as leaf.
-	 */
-	cmm_barrier();
-	pthread_mutex_lock(&ust_safe_guard_fd_mutex);
-	ust_safe_guard_saved_cancelstate = oldstate;
+	sigfillset(&sig_all_blocked);
+	ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+	if (ret) {
+		ERR("pthread_sigmask: %s", strerror(ret));
+	}
+	if (!URCU_TLS(ust_fd_mutex_nest)++) {
+		/*
+		 * Ensure the compiler don't move the store after the close()
+		 * call in case close() would be marked as leaf.
+		 */
+		cmm_barrier();
+		pthread_mutex_lock(&ust_safe_guard_fd_mutex);
+		ust_safe_guard_saved_cancelstate = oldstate;
+	}
+	ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
+	if (ret) {
+		ERR("pthread_sigmask: %s", strerror(ret));
+	}
 }
 
 void lttng_ust_unlock_fd_tracker(void)
 {
+	sigset_t sig_all_blocked, orig_mask;
 	int ret, newstate, oldstate;
+	bool restore_cancel = false;
 
-	newstate = ust_safe_guard_saved_cancelstate;
-	pthread_mutex_unlock(&ust_safe_guard_fd_mutex);
+	sigfillset(&sig_all_blocked);
+	ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+	if (ret) {
+		ERR("pthread_sigmask: %s", strerror(ret));
+	}
 	/*
 	 * Ensure the compiler don't move the store before the close()
 	 * call, in case close() would be marked as leaf.
 	 */
 	cmm_barrier();
-	URCU_TLS(thread_fd_tracking) = 0;
-	ret = pthread_setcancelstate(newstate, &oldstate);
+	if (!--URCU_TLS(ust_fd_mutex_nest)) {
+		newstate = ust_safe_guard_saved_cancelstate;
+		restore_cancel = true;
+		pthread_mutex_unlock(&ust_safe_guard_fd_mutex);
+	}
+	ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
 	if (ret) {
-		ERR("pthread_setcancelstate: %s", strerror(ret));
+		ERR("pthread_sigmask: %s", strerror(ret));
+	}
+	if (restore_cancel) {
+		ret = pthread_setcancelstate(newstate, &oldstate);
+		if (ret) {
+			ERR("pthread_setcancelstate: %s", strerror(ret));
+		}
 	}
 }
 
@@ -255,7 +294,7 @@ int lttng_ust_add_fd_to_tracker(int fd)
 	 * constructors.
 	 */
 	lttng_ust_init_fd_tracker();
-	assert(URCU_TLS(thread_fd_tracking));
+	assert(URCU_TLS(ust_fd_mutex_nest));
 
 	if (IS_FD_STD(fd)) {
 		ret = dup_std_fd(fd);
@@ -288,7 +327,7 @@ void lttng_ust_delete_fd_from_tracker(int fd)
 	 */
 	lttng_ust_init_fd_tracker();
 
-	assert(URCU_TLS(thread_fd_tracking));
+	assert(URCU_TLS(ust_fd_mutex_nest));
 	/* Not a valid fd. */
 	assert(IS_FD_VALID(fd));
 	/* Deleting an fd which was not set. */
@@ -462,3 +501,8 @@ int lttng_ust_safe_closefrom_fd(int lowfd, int (*close_cb)(int fd))
 end:
 	return ret;
 }
+
+void lttng_ust_fd_tracker_register_thread(void)
+{
+	URCU_TLS(thread_fd_tracking) = 1;
+}