Fix: Lock FD tracker across fork

[lttng-ust.git] / liblttng-ust-comm / lttng-ust-fd-tracker.c

diff --git a/liblttng-ust-comm/lttng-ust-fd-tracker.c b/liblttng-ust-comm/lttng-ust-fd-tracker.c
index 329339f98a038736fe528bc856bdeff1737b4c2b..282895911c65569c6a5050bb859b9e73383c1a5a 100644 (file)
--- a/liblttng-ust-comm/lttng-ust-fd-tracker.c
+++ b/liblttng-ust-comm/lttng-ust-fd-tracker.c
@@ -61,6 +61,9 @@
  * Protect the lttng_fd_set. Nests within the ust_lock, and therefore
  * within the libc dl lock. Therefore, we need to fixup the TLS before
  * nesting into this lock.
+ *
+ * The ust_safe_guard_fd_mutex nests within the ust_mutex. This mutex
+ * is also held across fork.
  */
 static pthread_mutex_t ust_safe_guard_fd_mutex = PTHREAD_MUTEX_INITIALIZER;
 /*
@@ -146,7 +149,7 @@ void lttng_ust_unlock_fd_tracker(void)
 
 static int dup_std_fd(int fd)
 {
-       int ret;
+       int ret, i;
        int fd_to_close[STDERR_FILENO + 1];
        int fd_to_close_count = 0;
        int dup_cmd = F_DUPFD; /* Default command */
@@ -171,7 +174,7 @@ static int dup_std_fd(int fd)
        }
 
        /* Perform dup */
-       for (int i = 0; i < STDERR_FILENO + 1; i++) {
+       for (i = 0; i < STDERR_FILENO + 1; i++) {
                ret = fcntl(fd, dup_cmd, 0);
                if (ret < 0) {
                        PERROR("fcntl dup fd");
@@ -192,7 +195,7 @@ static int dup_std_fd(int fd)
        }
 
        /* Close intermediary fds */
-       for (int i = 0; i < fd_to_close_count; i++) {
+       for (i = 0; i < fd_to_close_count; i++) {
                ret = close(fd_to_close[i]);
                if (ret) {
                        PERROR("close on temporary fd: %d.", fd_to_close[i]);