liblttng-ust-comm: move `_unlock_fd_tracker()` after `close()` on error paths

Right now, receiving an error from `lttng_ust_add_fd_to_tracker()` means that
the fd was _not_ added to the fd set. So the `lttng_ust_safe_close_fd()`
(overriding `close()`) call will indeed close the fd as expected. So, it
doesn't matter if the `close()` is before or after the `_unlock_`.

Even considering that, I believe that it's clearer and more common to
have all related operations within the `_lock_` and  `_unlock_`
functions. Also, `lttng_ust_add_fd_to_tracker()` might be modified in
the future and fail for some other reason.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Id29a6ab004cfd5ca601615e1a70c74cf754b12e2

diff --git a/liblttng-ust-comm/lttng-ust-comm.c b/liblttng-ust-comm/lttng-ust-comm.c
index 543465edf2fe2e2ee703a0d62e1b4c800d5d2f0d..9f2bdd5b3f80b650c04bbb6cb5ff37af74317880 100644 (file)
--- a/liblttng-ust-comm/lttng-ust-comm.c
+++ b/liblttng-ust-comm/lttng-ust-comm.c
@@ -631,12 +631,12 @@ ssize_t ustcomm_recv_channel_from_sessiond(int sock,
 
        ret = lttng_ust_add_fd_to_tracker(wakeup_fd);
        if (ret < 0) {
-               lttng_ust_unlock_fd_tracker();
                ret = close(wakeup_fd);
                if (ret) {
                        PERROR("close on wakeup_fd");
                }
                len = -EIO;
+               lttng_ust_unlock_fd_tracker();
                goto error_recv;
        }
 
@@ -677,19 +677,18 @@ int ustcomm_recv_stream_from_sessiond(int sock,
 
        ret = lttng_ust_add_fd_to_tracker(fds[0]);
        if (ret < 0) {
-               lttng_ust_unlock_fd_tracker();
                ret = close(fds[0]);
                if (ret) {
                        PERROR("close on received shm_fd");
                }
                ret = -EIO;
+               lttng_ust_unlock_fd_tracker();
                goto error;
        }
        *shm_fd = ret;
 
        ret = lttng_ust_add_fd_to_tracker(fds[1]);
        if (ret < 0) {
-               lttng_ust_unlock_fd_tracker();
                ret = close(*shm_fd);
                if (ret) {
                        PERROR("close on shm_fd");
@@ -700,6 +699,7 @@ int ustcomm_recv_stream_from_sessiond(int sock,
                        PERROR("close on received wakeup_fd");
                }
                ret = -EIO;
+               lttng_ust_unlock_fd_tracker();
                goto error;
        }
        *wakeup_fd = ret;