static pthread_mutex_t kconsumerd_pid_mutex; /* Mutex to control kconsumerd pid assignation */
+/*
+ * Pointer initialized before thread creation.
+ *
+ * This points to the tracing session list containing the session count and a
+ * mutex lock. The lock MUST be taken if you iterate over the list. The lock
+ * MUST NOT be taken if you call a public function in session.c.
+ */
+static struct ltt_session_list *session_list_ptr;
+
/*
* teardown_kernel_session
*
- * Complete teardown of a kernel session. This free all data structure
- * related to a kernel session and update counter.
+ * Complete teardown of a kernel session. This free all data structure related
+ * to a kernel session and update counter.
*/
static void teardown_kernel_session(struct ltt_session *session)
{
DBG("Cleaning up all session");
/* Cleanup ALL session */
- cds_list_for_each_entry(sess, <t_session_list.head, list) {
+ cds_list_for_each_entry(sess, &session_list_ptr->head, list) {
teardown_kernel_session(sess);
// TODO complete session cleanup (including UST)
}
+ /* Destroy session list mutex */
+ pthread_mutex_destroy(&session_list_ptr->lock);
+
DBG("Closing kernel fd");
close(kernel_tracer_fd);
close(kernel_poll_pipe[0]);
DBG("Updating kernel_pollfd");
/* Get the number of channel of all kernel session */
- cds_list_for_each_entry(session, <t_session_list.head, list) {
+ pthread_mutex_lock(&session_list_ptr->lock);
+ cds_list_for_each_entry(session, &session_list_ptr->head, list) {
+ lock_session(session);
if (session->kernel_session == NULL) {
+ unlock_session(session);
continue;
}
nb_fd += session->kernel_session->channel_count;
+ unlock_session(session);
}
DBG("Resizing kernel_pollfd to size %d", nb_fd);
goto error;
}
- cds_list_for_each_entry(session, <t_session_list.head, list) {
+ cds_list_for_each_entry(session, &session_list_ptr->head, list) {
+ lock_session(session);
if (session->kernel_session == NULL) {
+ unlock_session(session);
continue;
}
if (i >= nb_fd) {
ERR("To much channel for kernel_pollfd size");
+ unlock_session(session);
break;
}
cds_list_for_each_entry(channel, &session->kernel_session->channel_list.head, list) {
kernel_pollfd[i].events = POLLIN | POLLRDNORM;
i++;
}
+ unlock_session(session);
}
+ pthread_mutex_unlock(&session_list_ptr->lock);
/* Adding wake up pipe */
kernel_pollfd[nb_fd - 1].fd = kernel_poll_pipe[0];
return nb_fd;
error:
+ pthread_mutex_unlock(&session_list_ptr->lock);
return -1;
}
DBG("Updating kernel streams for channel fd %d", fd);
- cds_list_for_each_entry(session, <t_session_list.head, list) {
+ pthread_mutex_lock(&session_list_ptr->lock);
+ cds_list_for_each_entry(session, &session_list_ptr->head, list) {
+ lock_session(session);
if (session->kernel_session == NULL) {
+ unlock_session(session);
continue;
}
cds_list_for_each_entry(channel, &session->kernel_session->channel_list.head, list) {
goto end;
}
}
+ unlock_session(session);
}
end:
+ if (session) {
+ unlock_session(session);
+ }
+ pthread_mutex_unlock(&session_list_ptr->lock);
return ret;
}
* Check if the wake up pipe was triggered. If so, the kernel_pollfd
* must be updated.
*/
- if (kernel_pollfd[nb_fd - 1].revents == POLLIN) {
+ switch (kernel_pollfd[nb_fd - 1].revents) {
+ case POLLIN:
ret = read(kernel_poll_pipe[0], &tmp, 1);
update_poll_flag = 1;
continue;
+ case POLLERR:
+ goto error;
+ default:
+ break;
}
for (i = 0; i < nb_fd; i++) {
ret = LTTCOMM_SELECT_SESS;
}
goto error;
+ } else {
+ /* Acquire lock for the session */
+ lock_session(cmd_ctx->session);
}
break;
}
/* Set return code */
cmd_ctx->llm->ret_code = ret;
+ if (cmd_ctx->session) {
+ unlock_session(cmd_ctx->session);
+ }
+
return ret;
error:
cmd_ctx->llm->ret_code = ret;
setup_error:
+ if (cmd_ctx->session) {
+ unlock_session(cmd_ctx->session);
+ }
return ret;
}
goto error;
}
+ /* Get session list pointer */
+ session_list_ptr = get_session_list();
+
while (1) {
/* Create thread to manage the client socket */
ret = pthread_create(&client_thread, NULL, thread_manage_clients, (void *) NULL);
*/
#define _GNU_SOURCE
+#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "lttngerr.h"
#include "session.h"
-/* Variables */
-static unsigned int session_count;
-
-/* Static internal function */
-static void add_session_list(struct ltt_session *ls);
-static void del_session_list(struct ltt_session *ls);
-
-/* Init global session list */
-struct ltt_session_list ltt_session_list = {
- .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
-};
-
/*
- * get_session_list
+ * NOTES:
*
- * Return a pointer to the session list.
+ * No ltt_session.lock is taken here because those data structure are widely
+ * spread across the lttng-tools code base so before caling functions below
+ * that can read/write a session, the caller MUST acquire the session lock
+ * using lock_session() and unlock_session().
*/
-struct ltt_session_list *get_session_list(void)
-{
- return <t_session_list;
-}
/*
- * get_session_count
+ * Init tracing session list.
*
- * Return session_count
+ * Please see session.h for more explanation and correct usage of the list.
*/
-unsigned int get_session_count(void)
-{
- return session_count;
-}
+static struct ltt_session_list ltt_session_list = {
+ .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
+ .lock = PTHREAD_MUTEX_INITIALIZER,
+ .count = 0,
+};
/*
* add_session_list
*
* Add a ltt_session structure to the global list.
+ *
+ * The caller MUST acquire the session list lock before.
*/
static void add_session_list(struct ltt_session *ls)
{
cds_list_add(&ls->list, <t_session_list.head);
- session_count++;
+ ltt_session_list.count++;
}
/*
* del_session_list
*
* Delete a ltt_session structure to the global list.
+ *
+ * The caller MUST acquire the session list lock before.
*/
static void del_session_list(struct ltt_session *ls)
{
cds_list_del(&ls->list);
/* Sanity check */
- if (session_count != 0) {
- session_count--;
+ if (ltt_session_list.count > 0) {
+ ltt_session_list.count--;
}
}
+/*
+ * get_session_list
+ *
+ * Return a pointer to the session list.
+ */
+struct ltt_session_list *get_session_list(void)
+{
+ return <t_session_list;
+}
+
+/*
+ * Acquire session lock
+ */
+void lock_session(struct ltt_session *session)
+{
+ pthread_mutex_lock(&session->lock);
+}
+
+/*
+ * Release session lock
+ */
+void unlock_session(struct ltt_session *session)
+{
+ pthread_mutex_unlock(&session->lock);
+}
+
+/*
+ * get_session_count
+ *
+ * Return session_count
+ */
+unsigned int get_session_count(void)
+{
+ unsigned int count;
+
+ pthread_mutex_lock(<t_session_list.lock);
+ count = ltt_session_list.count;
+ pthread_mutex_unlock(<t_session_list.lock);
+
+ return count;
+}
+
/*
* find_session_by_name
*
int found = 0;
struct ltt_session *iter;
+ pthread_mutex_lock(<t_session_list.lock);
cds_list_for_each_entry(iter, <t_session_list.head, list) {
if (strncmp(iter->name, name, strlen(name)) == 0) {
found = 1;
break;
}
}
+ pthread_mutex_unlock(<t_session_list.lock);
if (!found) {
iter = NULL;
/*
* destroy_session
*
- * Delete session from the global session list
- * and free the memory.
+ * Delete session from the session list and free the memory.
*
- * Return -1 if no session is found.
- * On success, return 1;
+ * Return -1 if no session is found. On success, return 1;
*/
int destroy_session(char *name)
{
int found = -1;
struct ltt_session *iter;
+ pthread_mutex_lock(<t_session_list.lock);
cds_list_for_each_entry(iter, <t_session_list.head, list) {
if (strcmp(iter->name, name) == 0) {
DBG("Destroying session %s", iter->name);
del_session_list(iter);
+ free(iter->name);
+ free(iter->path);
+ pthread_mutex_destroy(&iter->lock);
free(iter);
found = 1;
break;
}
}
+ pthread_mutex_unlock(<t_session_list.lock);
return found;
}
/*
* create_session
*
- * Create a brand new session and add it to the global session list.
+ * Create a brand new session and add it to the session list.
*/
int create_session(char *name, char *path)
{
goto error;
}
- /*
- * Set consumer (identifier) to 0. This means that there is
- * NO consumer attach to that session yet.
- */
- new_session->ust_consumer = 0;
-
/* Init kernel session */
new_session->kernel_session = NULL;
/* Set trace list counter */
new_session->ust_trace_count = 0;
- /* Add new session to the global session list */
+ /* Add new session to the session list */
+ pthread_mutex_lock(<t_session_list.lock);
add_session_list(new_session);
+ pthread_mutex_unlock(<t_session_list.lock);
+
+ /* Init lock */
+ pthread_mutex_init(&new_session->lock, NULL);
- DBG("Tracing session %s created in %s", name, new_session->path);
+ DBG("Tracing session %s created in %s", new_session->name, new_session->path);
return 0;
DBG("Getting all available session");
- /* Iterate over session list and append data after
- * the control struct in the buffer.
+ /*
+ * Iterate over session list and append data after the control struct in
+ * the buffer.
*/
+ pthread_mutex_lock(<t_session_list.lock);
cds_list_for_each_entry(iter, <t_session_list.head, list) {
strncpy(lsess.path, iter->path, sizeof(lsess.path));
lsess.path[sizeof(lsess.path) - 1] = '\0';
/* Reset struct for next pass */
memset(&lsess, 0, sizeof(lsess));
}
+ pthread_mutex_unlock(<t_session_list.lock);
}
#include <lttng/lttng.h>
#include <urcu/list.h>
-/* Global session list */
+/*
+ * Tracing session list
+ *
+ * Statically declared in session.c and can be accessed by using
+ * get_session_list() function that returns the pointer to the list.
+ */
struct ltt_session_list {
+ /*
+ * This lock protects any read/write access to the list and count (which is
+ * basically the list size). All public functions in session.c acquire this
+ * lock and release it before returning. If none of those functions are
+ * used, the lock MUST be acquired in order to iterate or/and do any
+ * actions on that list.
+ */
+ pthread_mutex_t lock;
+ /*
+ * Number of element in the list.
+ */
+ unsigned int count;
struct cds_list_head head;
};
-extern struct ltt_session_list ltt_session_list;
-
-/* ltt-session - This data structure contains information needed
- * to identify a tracing session for both LTTng and UST.
+/*
+ * This data structure contains information needed to identify a tracing
+ * session for both LTTng and UST.
*/
struct ltt_session {
- struct cds_list_head list;
char *name;
char *path;
- struct cds_list_head ust_traces;
struct ltt_kernel_session *kernel_session;
+ struct cds_list_head ust_traces;
unsigned int ust_trace_count;
- pid_t ust_consumer;
+ /*
+ * Protect any read/write on this session data structure. This lock must be
+ * acquired *before* using any public functions declared below. Use
+ * lock_session() and unlock_session() for that.
+ */
+ pthread_mutex_t lock;
+ struct cds_list_head list;
};
/* Prototypes */
int create_session(char *name, char *path);
int destroy_session(char *name);
void get_lttng_session(struct lttng_session *sessions);
+void lock_session(struct ltt_session *session);
+void unlock_session(struct ltt_session *session);
struct ltt_session *find_session_by_name(char *name);
unsigned int get_session_count(void);
struct ltt_session_list *get_session_list(void);
projects / lttng-tools.git / commitdiff
