Use ust_lock during sock_info operations for atomicity against fork

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

diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index 7cd6a227d66c3bede0f7e244a02038c2c8de668b..0cf5ecd9687536be5fc7794c4bfeb28ed135a11f 100644 (file)
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -35,6 +35,7 @@
 #include <time.h>
 #include <assert.h>
 #include <signal.h>
+#include <limits.h>
 #include <urcu/uatomic.h>
 #include <urcu/futex.h>
 #include <urcu/compiler.h>
@@ -52,7 +53,7 @@
 #include "tracepoint-internal.h"
 #include "lttng-tracer-core.h"
 #include "compat.h"
-#include "../libringbuffer/tlsfixup.h"
+#include "../libringbuffer/rb-init.h"
 #include "lttng-ust-statedump.h"
 #include "clock.h"
 #include "../libringbuffer/getcpu.h"
@@ -365,11 +366,11 @@ const char *get_lttng_home_dir(void)
 {
        const char *val;
 
-       val = (const char *) lttng_secure_getenv("LTTNG_HOME");
+       val = (const char *) lttng_getenv("LTTNG_HOME");
        if (val != NULL) {
                return val;
        }
-       return (const char *) lttng_secure_getenv("HOME");
+       return (const char *) lttng_getenv("HOME");
 }
 
 /*
@@ -470,7 +471,7 @@ long get_timeout(void)
        long constructor_delay_ms = LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS;
 
        if (!got_timeout_env) {
-               str_timeout = getenv("LTTNG_UST_REGISTER_TIMEOUT");
+               str_timeout = lttng_getenv("LTTNG_UST_REGISTER_TIMEOUT");
                got_timeout_env = 1;
        }
        if (str_timeout)
@@ -533,6 +534,19 @@ int get_constructor_timeout(struct timespec *constructor_timeout)
        return 1;
 }
 
+static
+void get_allow_blocking(void)
+{
+       const char *str_allow_blocking =
+               lttng_getenv("LTTNG_UST_ALLOW_BLOCKING");
+
+       if (str_allow_blocking) {
+               DBG("%s environment variable is set",
+                       "LTTNG_UST_ALLOW_BLOCKING");
+               lttng_ust_ringbuffer_set_allow_blocking();
+       }
+}
+
 static
 int register_to_sessiond(int socket, enum ustctl_socket_type type)
 {
@@ -1247,7 +1261,18 @@ char *get_map_shm(struct sock_info *sock_info)
                lttng_ust_unlock_fd_tracker();
                goto error;
        }
-       lttng_ust_add_fd_to_tracker(wait_shm_fd);
+
+       ret = lttng_ust_add_fd_to_tracker(wait_shm_fd);
+       if (ret < 0) {
+               ret = close(wait_shm_fd);
+               if (!ret) {
+                       PERROR("Error closing fd");
+               }
+               lttng_ust_unlock_fd_tracker();
+               goto error;
+       }
+
+       wait_shm_fd = ret;
        lttng_ust_unlock_fd_tracker();
 
        wait_shm_mmap = mmap(NULL, page_size, PROT_READ,
@@ -1339,7 +1364,7 @@ static
 void *ust_listener_thread(void *arg)
 {
        struct sock_info *sock_info = arg;
-       int sock, ret, prev_connect_failed = 0, has_waited = 0;
+       int sock, ret, prev_connect_failed = 0, has_waited = 0, fd;
        long timeout;
 
        lttng_ust_fixup_tls();
@@ -1371,6 +1396,10 @@ restart:
                prev_connect_failed = 0;
        }
 
+       if (ust_lock()) {
+               goto quit;
+       }
+
        if (sock_info->socket != -1) {
                /* FD tracker is updated by ustcomm_close_unix_sock() */
                ret = ustcomm_close_unix_sock(sock_info->socket);
@@ -1390,9 +1419,6 @@ restart:
                sock_info->notify_socket = -1;
        }
 
-       if (ust_lock()) {
-               goto quit;
-       }
 
        /*
         * Register. We need to perform both connect and sending
@@ -1419,9 +1445,21 @@ restart:
                ust_unlock();
                goto restart;
        }
-       lttng_ust_add_fd_to_tracker(ret);
-       lttng_ust_unlock_fd_tracker();
+       fd = ret;
+       ret = lttng_ust_add_fd_to_tracker(fd);
+       if (ret < 0) {
+               ret = close(fd);
+               if (ret) {
+                       PERROR("close on sock_info->socket");
+               }
+               ret = -1;
+               lttng_ust_unlock_fd_tracker();
+               ust_unlock();
+               goto quit;
+       }
+
        sock_info->socket = ret;
+       lttng_ust_unlock_fd_tracker();
 
        ust_unlock();
        /*
@@ -1490,9 +1528,22 @@ restart:
                ust_unlock();
                goto restart;
        }
-       lttng_ust_add_fd_to_tracker(ret);
-       lttng_ust_unlock_fd_tracker();
+
+       fd = ret;
+       ret = lttng_ust_add_fd_to_tracker(fd);
+       if (ret < 0) {
+               ret = close(fd);
+               if (ret) {
+                       PERROR("close on sock_info->notify_socket");
+               }
+               ret = -1;
+               lttng_ust_unlock_fd_tracker();
+               ust_unlock();
+               goto quit;
+       }
+
        sock_info->notify_socket = ret;
+       lttng_ust_unlock_fd_tracker();
 
        ust_unlock();
        /*
@@ -1654,6 +1705,7 @@ void __attribute__((constructor)) lttng_ust_init(void)
         * sessiond before the init functions are completed).
         */
        init_usterr();
+       lttng_ust_getenv_init();        /* Needs init_usterr() to be completed. */
        init_tracepoint();
        lttng_ust_init_fd_tracker();
        lttng_ust_clock_init();
@@ -1672,6 +1724,8 @@ void __attribute__((constructor)) lttng_ust_init(void)
 
        timeout_mode = get_constructor_timeout(&constructor_timeout);
 
+       get_allow_blocking();
+
        ret = sem_init(&constructor_wait, 0, 0);
        if (ret) {
                PERROR("sem_init");