Filter: Implement stack-based interpreter

[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 1a1f7181df22c262c4e3bb5a4546cac97ee95793..cca5dcf83716d9ce0e854305185689290b3e72aa 100644 (file)
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -43,6 +43,7 @@
 #include <lttng/ust.h>
 #include <ust-comm.h>
 #include <usterr-signal-safe.h>
+#include <helper.h>
 #include "tracepoint-internal.h"
 #include "ltt-tracer-core.h"
 #include "compat.h"
@@ -78,6 +79,12 @@ static sem_t constructor_wait;
  */
 static int sem_count = { 2 };
 
+/*
+ * Counting nesting within lttng-ust. Used to ensure that calling fork()
+ * from liblttng-ust does not execute the pre/post fork handlers.
+ */
+static int __thread lttng_ust_nest_count;
+
 /*
  * Info about socket and associated listener thread.
  */
@@ -130,6 +137,15 @@ extern void ltt_ring_buffer_client_overwrite_exit(void);
 extern void ltt_ring_buffer_client_discard_exit(void);
 extern void ltt_ring_buffer_metadata_client_exit(void);
 
+/*
+ * Force a read (imply TLS fixup for dlopen) of TLS variables.
+ */
+static
+void lttng_fixup_nest_count_tls(void)
+{
+       asm volatile ("" : : "m" (lttng_ust_nest_count));
+}
+
 static
 int setup_local_apps(void)
 {
@@ -266,6 +282,66 @@ int handle_message(struct sock_info *sock_info,
                else
                        ret = lttng_ust_objd_unref(lum->handle);
                break;
+       case LTTNG_UST_FILTER:
+       {
+               /* Receive filter data */
+               struct lttng_ust_filter_bytecode *bytecode;
+
+               if (lum->u.filter.data_size > FILTER_BYTECODE_MAX_LEN) {
+                       ERR("Filter data size is too large: %u bytes\n",
+                               lum->u.filter.data_size);
+                       ret = -EINVAL;
+                       goto error;
+               }
+               bytecode = zmalloc(sizeof(*bytecode) + lum->u.filter.data_size);
+               if (!bytecode) {
+                       ret = -ENOMEM;
+                       goto error;
+               }
+               len = ustcomm_recv_unix_sock(sock, bytecode->data,
+                               lum->u.filter.data_size);
+               switch (len) {
+               case 0: /* orderly shutdown */
+                       ret = 0;
+                       free(bytecode);
+                       goto error;
+               case -1:
+                       DBG("Receive failed from lttng-sessiond with errno %d", errno);
+                       if (errno == ECONNRESET) {
+                               ERR("%s remote end closed connection\n", sock_info->name);
+                               ret = -EINVAL;
+                               free(bytecode);
+                               goto error;
+                       }
+                       ret = -EINVAL;
+                       goto end;
+               default:
+                       if (len == lum->u.filter.data_size) {
+                               DBG("filter data received\n");
+                               break;
+                       } else {
+                               ERR("incorrect filter data message size: %zd\n", len);
+                               ret = -EINVAL;
+                               free(bytecode);
+                               goto end;
+                       }
+               }
+               bytecode->len = lum->u.filter.data_size;
+               bytecode->reloc_offset = lum->u.filter.reloc_offset;
+               if (ops->cmd) {
+                       ret = ops->cmd(lum->handle, lum->cmd,
+                                       (unsigned long) bytecode,
+                                       &args);
+                       if (ret) {
+                               free(bytecode);
+                       }
+                       /* don't free bytecode if everything went fine. */
+               } else {
+                       ret = -ENOSYS;
+                       free(bytecode);
+               }
+               break;
+       }
        default:
                if (ops->cmd)
                        ret = ops->cmd(lum->handle, lum->cmd,
@@ -481,7 +557,9 @@ int get_wait_shm(struct sock_info *sock_info, size_t mmap_size)
         * If the open failed because the file did not exist, try
         * creating it ourself.
         */
+       lttng_ust_nest_count++;
        pid = fork();
+       lttng_ust_nest_count--;
        if (pid > 0) {
                int status;
 
@@ -664,7 +742,7 @@ error:
  * This thread does not allocate any resource, except within
  * handle_message, within mutex protection. This mutex protects against
  * fork and exit.
- * The other moment it allocates resources is at socket connexion, which
+ * The other moment it allocates resources is at socket connection, which
  * is also protected by the mutex.
  */
 static
@@ -864,6 +942,7 @@ void __attribute__((constructor)) lttng_ust_init(void)
        lttng_fixup_event_tls();
        lttng_fixup_ringbuffer_tls();
        lttng_fixup_vtid_tls();
+       lttng_fixup_nest_count_tls();
 
        /*
         * We want precise control over the order in which we construct
@@ -895,15 +974,20 @@ void __attribute__((constructor)) lttng_ust_init(void)
        sigfillset(&sig_all_blocked);
        ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask);
        if (ret) {
-               PERROR("pthread_sigmask: %s", strerror(ret));
+               ERR("pthread_sigmask: %s", strerror(ret));
        }
 
        ret = pthread_create(&global_apps.ust_listener, NULL,
                        ust_listener_thread, &global_apps);
-
+       if (ret) {
+               ERR("pthread_create global: %s", strerror(ret));
+       }
        if (local_apps.allowed) {
                ret = pthread_create(&local_apps.ust_listener, NULL,
                                ust_listener_thread, &local_apps);
+               if (ret) {
+                       ERR("pthread_create local: %s", strerror(ret));
+               }
        } else {
                handle_register_done(&local_apps);
        }
@@ -911,7 +995,7 @@ void __attribute__((constructor)) lttng_ust_init(void)
        /* Restore original signal mask in parent */
        ret = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL);
        if (ret) {
-               PERROR("pthread_sigmask: %s", strerror(ret));
+               ERR("pthread_sigmask: %s", strerror(ret));
        }
 
        switch (timeout_mode) {
@@ -987,12 +1071,14 @@ void __attribute__((destructor)) lttng_ust_exit(void)
        /* cancel threads */
        ret = pthread_cancel(global_apps.ust_listener);
        if (ret) {
-               ERR("Error cancelling global ust listener thread");
+               ERR("Error cancelling global ust listener thread: %s",
+                       strerror(ret));
        }
        if (local_apps.allowed) {
                ret = pthread_cancel(local_apps.ust_listener);
                if (ret) {
-                       ERR("Error cancelling local ust listener thread");
+                       ERR("Error cancelling local ust listener thread: %s",
+                               strerror(ret));
                }
        }
        /*
@@ -1024,6 +1110,8 @@ void ust_before_fork(sigset_t *save_sigset)
        sigset_t all_sigs;
        int ret;
 
+       if (lttng_ust_nest_count)
+               return;
        /* Disable signals */
        sigfillset(&all_sigs);
        ret = sigprocmask(SIG_BLOCK, &all_sigs, save_sigset);
@@ -1049,6 +1137,8 @@ static void ust_after_fork_common(sigset_t *restore_sigset)
 
 void ust_after_fork_parent(sigset_t *restore_sigset)
 {
+       if (lttng_ust_nest_count)
+               return;
        DBG("process %d", getpid());
        rcu_bp_after_fork_parent();
        /* Release mutexes and reenable signals */
@@ -1066,6 +1156,8 @@ void ust_after_fork_parent(sigset_t *restore_sigset)
  */
 void ust_after_fork_child(sigset_t *restore_sigset)
 {
+       if (lttng_ust_nest_count)
+               return;
        DBG("process %d", getpid());
        /* Release urcu mutexes */
        rcu_bp_after_fork_child();