Adapt lttng-ust to use multiflavor symbols from liburcu 0.11

[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 511b9cf4a88214c0225ff8a7e15a63cbca32145e..a09f676a42978146fd8d7d12b1e2638738c37334 100644 (file)
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -27,6 +27,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <dlfcn.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <errno.h>
@@ -59,6 +60,9 @@
 #include "../libringbuffer/getcpu.h"
 #include "getenv.h"
 
+/* Concatenate lttng ust shared library name with its major version number. */
+#define LTTNG_UST_LIB_SO_NAME "liblttng-ust.so." LTTNG_UST_LIBRARY_VERSION_MAJOR
+
 /*
  * Has lttng ust comm constructor been called ?
  */
@@ -1261,7 +1265,18 @@ 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,
@@ -1353,7 +1368,7 @@ 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();
@@ -1385,6 +1400,10 @@ 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);
@@ -1404,9 +1423,6 @@ restart:
                sock_info->notify_socket = -1;
        }
 
-       if (ust_lock()) {
-               goto quit;
-       }
 
        /*
         * Register. We need to perform both connect and sending
@@ -1433,9 +1449,21 @@ 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();
        /*
@@ -1504,9 +1532,22 @@ 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();
        /*
@@ -1648,6 +1689,7 @@ void __attribute__((constructor)) lttng_ust_init(void)
        pthread_attr_t thread_attr;
        int timeout_mode;
        int ret;
+       void *handle;
 
        if (uatomic_xchg(&initialized, 1) == 1)
                return;
@@ -1661,6 +1703,26 @@ void __attribute__((constructor)) lttng_ust_init(void)
 
        lttng_ust_loaded = 1;
 
+       /*
+        * We need to ensure that the liblttng-ust library is not unloaded to avoid
+        * the unloading of code used by the ust_listener_threads as we can not
+        * reliably know when they exited. To do that, manually load
+        * liblttng-ust.so to increment the dynamic loader's internal refcount for
+        * this library so it never becomes zero, thus never gets unloaded from the
+        * address space of the process. Since we are already running in the
+        * constructor of the LTTNG_UST_LIB_SO_NAME library, calling dlopen will
+        * simply increment the refcount and no additionnal work is needed by the
+        * dynamic loader as the shared library is already loaded in the address
+        * space. As a safe guard, we use the RTLD_NODELETE flag to prevent
+        * unloading of the UST library if its refcount becomes zero (which should
+        * never happen). Do the return value check but discard the handle at the
+        * end of the function as it's not needed.
+        */
+       handle = dlopen(LTTNG_UST_LIB_SO_NAME, RTLD_LAZY | RTLD_NODELETE);
+       if (!handle) {
+               ERR("dlopen of liblttng-ust shared library (%s).", LTTNG_UST_LIB_SO_NAME);
+       }
+
        /*
         * We want precise control over the order in which we construct
         * our sub-libraries vs starting to receive commands from
@@ -1907,7 +1969,7 @@ void ust_before_fork(sigset_t *save_sigset)
        pthread_mutex_lock(&ust_fork_mutex);
 
        ust_lock_nocheck();
-       rcu_bp_before_fork();
+       urcu_bp_before_fork();
 }
 
 static void ust_after_fork_common(sigset_t *restore_sigset)
@@ -1931,7 +1993,7 @@ void ust_after_fork_parent(sigset_t *restore_sigset)
        if (URCU_TLS(lttng_ust_nest_count))
                return;
        DBG("process %d", getpid());
-       rcu_bp_after_fork_parent();
+       urcu_bp_after_fork_parent();
        /* Release mutexes and reenable signals */
        ust_after_fork_common(restore_sigset);
 }
@@ -1949,10 +2011,12 @@ void ust_after_fork_child(sigset_t *restore_sigset)
 {
        if (URCU_TLS(lttng_ust_nest_count))
                return;
+       lttng_context_vpid_reset();
        lttng_context_vtid_reset();
+       lttng_context_procname_reset();
        DBG("process %d", getpid());
        /* Release urcu mutexes */
-       rcu_bp_after_fork_child();
+       urcu_bp_after_fork_child();
        lttng_ust_cleanup(0);
        /* Release mutexes and reenable signals */
        ust_after_fork_common(restore_sigset);