Add the notify UST application scheme
[lttng-tools.git] / ltt-sessiond / main.c
index a3335292bc0760746a701f0426d79a6a011dd34a..85ac06be9e32c2967417513b7902d2b226b303ba 100644 (file)
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
- * Copyright (C) 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/mman.h>
 #include <sys/mount.h>
 #include <sys/resource.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <sys/wait.h>
+#include <urcu/futex.h>
 #include <unistd.h>
 
 #include <ltt-kconsumerd.h>
@@ -45,6 +48,7 @@
 #include "futex.h"
 #include "kernel-ctl.h"
 #include "ltt-sessiond.h"
+#include "shm.h"
 #include "traceable-app.h"
 #include "ust-ctl.h"
 #include "utils.h"
@@ -75,6 +79,7 @@ static char apps_unix_sock_path[PATH_MAX];                            /* Global application Unix socket
 static char client_unix_sock_path[PATH_MAX];                   /* Global client Unix socket path */
 static char kconsumerd_err_unix_sock_path[PATH_MAX];   /* kconsumerd error Unix socket path */
 static char kconsumerd_cmd_unix_sock_path[PATH_MAX];   /* kconsumerd command Unix socket path */
+static char wait_shm_path[PATH_MAX];                    /* global wait shm path for UST */
 
 /* Sockets and FDs */
 static int client_sock;
@@ -107,8 +112,6 @@ static sem_t kconsumerd_sem;
 
 static pthread_mutex_t kconsumerd_pid_mutex;   /* Mutex to control kconsumerd pid assignation */
 
-static int modprobe_remove_kernel_modules(void);
-
 /*
  * UST registration command queue. This queue is tied with a futex and uses a N
  * wakers / 1 waiter implemented and detailed in futex.c/.h
@@ -130,6 +133,44 @@ static struct ust_cmd_queue ust_cmd_queue;
  */
 static struct ltt_session_list *session_list_ptr;
 
+/*
+ * Remove modules in reverse load order.
+ */
+static int modprobe_remove_kernel_modules(void)
+{
+       int ret = 0, i;
+       char modprobe[256];
+
+       for (i = ARRAY_SIZE(kernel_modules_list) - 1; i >= 0; i--) {
+               ret = snprintf(modprobe, sizeof(modprobe),
+                               "/sbin/modprobe --remove --quiet %s",
+                               kernel_modules_list[i].name);
+               if (ret < 0) {
+                       perror("snprintf modprobe --remove");
+                       goto error;
+               }
+               modprobe[sizeof(modprobe) - 1] = '\0';
+               ret = system(modprobe);
+               if (ret == -1) {
+                       ERR("Unable to launch modprobe --remove for module %s",
+                                       kernel_modules_list[i].name);
+               } else if (kernel_modules_list[i].required
+                               && WEXITSTATUS(ret) != 0) {
+                       ERR("Unable to remove module %s",
+                                       kernel_modules_list[i].name);
+               } else {
+                       DBG("Modprobe removal successful %s",
+                                       kernel_modules_list[i].name);
+               }
+       }
+
+error:
+       return ret;
+}
+
+/*
+ * Return group ID of the tracing group or -1 if not found.
+ */
 static gid_t allowed_group(void)
 {
        struct group *grp;
@@ -405,37 +446,30 @@ error:
        return ret;
 }
 
-#ifdef DISABLED
 /*
- * Notify apps by writing 42 to a named pipe using name. Every applications
- * waiting for a ltt-sessiond will be notified and re-register automatically to
- * the session daemon.
- *
- * Return open or write error value.
+ * Notify UST applications using the shm mmap futex.
  */
-static int notify_apps(const char *name)
+static int notify_ust_apps(int active)
 {
-       int fd;
-       int ret = -1;
+       char *wait_shm_mmap;
 
-       DBG("Notify the global application pipe");
+       DBG("Notifying applications of session daemon state: %d", active);
 
-       /* Try opening the global pipe */
-       fd = open(name, O_WRONLY);
-       if (fd < 0) {
+       /* See shm.c for this call implying mmap, shm and futex calls */
+       wait_shm_mmap = shm_ust_get_mmap(wait_shm_path, is_root);
+       if (wait_shm_mmap == NULL) {
                goto error;
        }
 
-       /* Notify by writing on the pipe */
-       ret = write(fd, "42", 2);
-       if (ret < 0) {
-               perror("write");
-       }
+       /* Wake waiting process */
+       futex_wait_update((int32_t *) wait_shm_mmap, active);
+
+       /* Apps notified successfully */
+       return 0;
 
 error:
-       return ret;
+       return -1;
 }
-#endif /* DISABLED */
 
 /*
  * Setup the outgoing data buffer for the response (llm) by allocating the
@@ -1067,7 +1101,12 @@ static void *thread_registration_apps(void *data)
        pollfd[1].events = POLLIN;
 
        /* Notify all applications to register */
-       //notify_apps(default_global_apps_pipe);
+       ret = notify_ust_apps(1);
+       if (ret < 0) {
+               ERR("Failed to notify applications or create the wait shared memory.\n"
+                       "Execution continues but there might be problem for already running\n"
+                       "applications that wishes to register.");
+       }
 
        while (1) {
                DBG("Accepting application registration");
@@ -1138,15 +1177,16 @@ static void *thread_registration_apps(void *data)
        }
 
 error:
-       DBG("Register apps thread dying");
-       if (apps_sock) {
-               close(apps_sock);
-       }
-       if (sock) {
-               close(sock);
-       }
+       DBG("UST Registration thread dying");
+
+       /* Notify that the registration thread is gone */
+       notify_ust_apps(0);
+
+       close(apps_sock);
+       close(sock);
 
        unlink(apps_unix_sock_path);
+
        return NULL;
 }
 
@@ -1320,42 +1360,6 @@ error:
        return ret;
 }
 
-/*
- * modprobe_remove_kernel_modules
- * Remove modules in reverse load order.
- */
-static int modprobe_remove_kernel_modules(void)
-{
-       int ret = 0, i;
-       char modprobe[256];
-
-       for (i = ARRAY_SIZE(kernel_modules_list) - 1; i >= 0; i--) {
-               ret = snprintf(modprobe, sizeof(modprobe),
-                       "/sbin/modprobe --remove --quiet %s",
-                       kernel_modules_list[i].name);
-               if (ret < 0) {
-                       perror("snprintf modprobe --remove");
-                       goto error;
-               }
-               modprobe[sizeof(modprobe) - 1] = '\0';
-               ret = system(modprobe);
-               if (ret == -1) {
-                       ERR("Unable to launch modprobe --remove for module %s",
-                               kernel_modules_list[i].name);
-               } else if (kernel_modules_list[i].required
-                               && WEXITSTATUS(ret) != 0) {
-                       ERR("Unable to remove module %s",
-                               kernel_modules_list[i].name);
-               } else {
-                       DBG("Modprobe removal successful %s",
-                               kernel_modules_list[i].name);
-               }
-       }
-
-error:
-       return ret;
-}
-
 /*
  * mount_debugfs
  */
@@ -1788,6 +1792,8 @@ static int process_client_msg(struct command_ctx *cmd_ctx)
                        }
                }
                break;
+       case LTTNG_DOMAIN_UST_PID:
+               break;
        default:
                break;
        }
@@ -1999,6 +2005,7 @@ static int process_client_msg(struct command_ctx *cmd_ctx)
                        kernel_wait_quiescent(kernel_tracer_fd);
                        break;
                case LTTNG_DOMAIN_UST_PID:
+
                        break;
                default:
                        ret = LTTCOMM_NOT_IMPLEMENTED;
@@ -3134,6 +3141,12 @@ int main(int argc, char **argv)
                        snprintf(client_unix_sock_path, PATH_MAX,
                                        DEFAULT_GLOBAL_CLIENT_UNIX_SOCK);
                }
+
+               /* Set global SHM for ust */
+               if (strlen(wait_shm_path) == 0) {
+                       snprintf(wait_shm_path, PATH_MAX,
+                                       DEFAULT_GLOBAL_APPS_WAIT_SHM_PATH);
+               }
        } else {
                home_path = get_home_dir();
                if (home_path == NULL) {
@@ -3153,6 +3166,12 @@ int main(int argc, char **argv)
                        snprintf(client_unix_sock_path, PATH_MAX,
                                        DEFAULT_HOME_CLIENT_UNIX_SOCK, home_path);
                }
+
+               /* Set global SHM for ust */
+               if (strlen(wait_shm_path) == 0) {
+                       snprintf(wait_shm_path, PATH_MAX,
+                                       DEFAULT_HOME_APPS_WAIT_SHM_PATH, geteuid());
+               }
        }
 
        DBG("Client socket path %s", client_unix_sock_path);
This page took 0.026183 seconds and 4 git commands to generate.