Fix: perform TLS fixup in all UST entry points from each thread

Each entry point into lttng-ust that end up taking the ust lock need to
perform a TLS fixup for each thread. Add a TLS fixup in both listener
threads, in fork and base address dump helper libs, and in app context
and tracepoint probe registration/unregistration functions, which can be
called from application threads.

Those ensure we don't take the libc dl lock within the ust lock when
performing the TLS lazy fixup.

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

diff --git a/liblttng-ust/lttng-probes.c b/liblttng-ust/lttng-probes.c
index bba5cd345238b25db0340c77c52ae991584a30a9..4b5259230d97d5cec6e524b0b607162a31ab8d5a 100644 (file)
--- a/liblttng-ust/lttng-probes.c
+++ b/liblttng-ust/lttng-probes.c
@@ -194,6 +194,8 @@ int lttng_probe_register(struct lttng_probe_desc *desc)
 {
        int ret = 0;
 
+       lttng_ust_fixup_tls();
+
        /*
         * If version mismatch, don't register, but don't trigger assert
         * on caller. The version check just prints an error.
@@ -234,6 +236,8 @@ int ltt_probe_register(struct lttng_probe_desc *desc)
 
 void lttng_probe_unregister(struct lttng_probe_desc *desc)
 {
+       lttng_ust_fixup_tls();
+
        if (!check_provider_version(desc))
                return;
 

diff --git a/liblttng-ust/lttng-tracer-core.h b/liblttng-ust/lttng-tracer-core.h
index 4e0d2c69d70f2510811a80432e22ab2a43e79a3b..f8a60640b9e9cce65dc394852c0f117d8300c625 100644 (file)
--- a/liblttng-ust/lttng-tracer-core.h
+++ b/liblttng-ust/lttng-tracer-core.h
@@ -50,4 +50,6 @@ void lttng_ust_sockinfo_session_enabled(void *owner);
 
 void lttng_ust_malloc_wrapper_init(void);
 
+void lttng_ust_fixup_tls(void);
+
 #endif /* _LTTNG_TRACER_CORE_H */

diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index 7842af795da31e4f59eb800c9c5a58e94517ba85..373a1c2df6b177e4bd6bc2378359e19bd713b87a 100644 (file)
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -370,6 +370,16 @@ void lttng_fixup_urcu_bp_tls(void)
        rcu_read_unlock();
 }
 
+void lttng_ust_fixup_tls(void)
+{
+       lttng_fixup_urcu_bp_tls();
+       lttng_fixup_ringbuffer_tls();
+       lttng_fixup_vtid_tls();
+       lttng_fixup_nest_count_tls();
+       lttng_fixup_procname_tls();
+       lttng_fixup_ust_mutex_nest_tls();
+}
+
 int lttng_get_notify_socket(void *owner)
 {
        struct sock_info *info = owner;
@@ -1218,6 +1228,8 @@ void *ust_listener_thread(void *arg)
        int sock, ret, prev_connect_failed = 0, has_waited = 0;
        long timeout;
 
+       lttng_ust_fixup_tls();
+
        /* Restart trying to connect to the session daemon */
 restart:
        if (prev_connect_failed) {
@@ -1481,12 +1493,7 @@ void __attribute__((constructor)) lttng_ust_init(void)
         * to be the dynamic linker mutex) and ust_lock, taken within
         * the ust lock.
         */
-       lttng_fixup_urcu_bp_tls();
-       lttng_fixup_ringbuffer_tls();
-       lttng_fixup_vtid_tls();
-       lttng_fixup_nest_count_tls();
-       lttng_fixup_procname_tls();
-       lttng_fixup_ust_mutex_nest_tls();
+       lttng_ust_fixup_tls();
 
        /*
         * We want precise control over the order in which we construct
@@ -1717,6 +1724,9 @@ void ust_before_fork(sigset_t *save_sigset)
        sigset_t all_sigs;
        int ret;
 
+       /* Fixup lttng-ust TLS. */
+       lttng_ust_fixup_tls();
+
        if (URCU_TLS(lttng_ust_nest_count))
                return;
        /* Disable signals */

diff --git a/liblttng-ust/lttng-ust-statedump.c b/liblttng-ust/lttng-ust-statedump.c
index 4f989bca9729acb2e931cd614b6520756c4fc9ee..b4d93fdddfe8b67922e29b235975dbd3e77e778b 100644 (file)
--- a/liblttng-ust/lttng-ust-statedump.c
+++ b/liblttng-ust/lttng-ust-statedump.c
@@ -218,6 +218,12 @@ int do_baddr_statedump(void *owner)
        if (getenv("LTTNG_UST_WITHOUT_BADDR_STATEDUMP"))
                return 0;
 
+       /*
+        * Fixup lttng-ust TLS when called from dlopen/dlclose
+        * instrumentation.
+        */
+       lttng_ust_fixup_tls();
+
        data.owner = owner;
        data.exec_found = 0;
        /*