From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 11 Oct 2019 14:12:04 +0000 (-0400)
Subject: Revert "Fix: fd tracker: do not allow signal handlers to close lttng-ust FDs"
X-Git-Tag: v2.11.0-rc5~2
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=82192e53382381e9295dcea7d1b9cd46a3913e6a;p=lttng-ust.git

Revert "Fix: fd tracker: do not allow signal handlers to close lttng-ust FDs"

This reverts commit 01be959de2f1879fcd54a47a74ff443e2ef12f90.

Fixes: #1204
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/include/ust-fd.h b/include/ust-fd.h
index 327a5f95..a0155251 100644
--- a/include/ust-fd.h
+++ b/include/ust-fd.h
@@ -31,7 +31,6 @@ int lttng_ust_add_fd_to_tracker(int fd);
 void lttng_ust_delete_fd_from_tracker(int fd);
 void lttng_ust_lock_fd_tracker(void);
 void lttng_ust_unlock_fd_tracker(void);
-void lttng_ust_fd_tracker_register_thread(void);
 
 int lttng_ust_safe_close_fd(int fd, int (*close_cb)(int));
 int lttng_ust_safe_fclose_stream(FILE *stream, int (*fclose_cb)(FILE *stream));
diff --git a/liblttng-ust-comm/lttng-ust-fd-tracker.c b/liblttng-ust-comm/lttng-ust-fd-tracker.c
index 42c3984c..9659f349 100644
--- a/liblttng-ust-comm/lttng-ust-fd-tracker.c
+++ b/liblttng-ust-comm/lttng-ust-fd-tracker.c
@@ -77,20 +77,12 @@ 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. 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.
+ * system call override by LD_PRELOAD library. This also tracks 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;
@@ -102,7 +94,6 @@ 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)));
 }
 
@@ -357,7 +348,7 @@ int lttng_ust_safe_close_fd(int fd, int (*close_cb)(int fd))
 	 * If called from lttng-ust, we directly call close without
 	 * validating whether the FD is part of the tracked set.
 	 */
-	if (URCU_TLS(thread_fd_tracking))
+	if (URCU_TLS(ust_fd_mutex_nest))
 		return close_cb(fd);
 
 	lttng_ust_lock_fd_tracker();
@@ -393,7 +384,7 @@ int lttng_ust_safe_fclose_stream(FILE *stream, int (*fclose_cb)(FILE *stream))
 	 * If called from lttng-ust, we directly call fclose without
 	 * validating whether the FD is part of the tracked set.
 	 */
-	if (URCU_TLS(thread_fd_tracking))
+	if (URCU_TLS(ust_fd_mutex_nest))
 		return fclose_cb(stream);
 
 	fd = fileno(stream);
@@ -456,7 +447,7 @@ int lttng_ust_safe_closefrom_fd(int lowfd, int (*close_cb)(int fd))
 	 * If called from lttng-ust, we directly call close without
 	 * validating whether the FD is part of the tracked set.
 	 */
-	if (URCU_TLS(thread_fd_tracking)) {
+	if (URCU_TLS(ust_fd_mutex_nest)) {
 		for (i = lowfd; i < lttng_ust_max_fd; i++) {
 			if (close_cb(i) < 0) {
 				switch (errno) {
@@ -501,8 +492,3 @@ 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;
-}
diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index f91f8fd9..4d851978 100644
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -1457,7 +1457,6 @@ void *ust_listener_thread(void *arg)
 	long timeout;
 
 	lttng_ust_fixup_tls();
-	lttng_ust_fd_tracker_register_thread();
 	/*
 	 * If available, add '-ust' to the end of this thread's
 	 * process name