Initial work for kernel tracing support

[lttng-tools.git] / ltt-sessiond / trace.c

diff --git a/ltt-sessiond/trace.c b/ltt-sessiond/trace.c
index c5d700fd1450b17d842c20a93eef220d75e83d5d..1cddb31fac9c6bb68a8a9f401e6567a08941f33d 100644 (file)
--- a/ltt-sessiond/trace.c
+++ b/ltt-sessiond/trace.c
@@ -23,10 +23,16 @@
 #include <stdlib.h>
 #include <string.h>
 #include <urcu/list.h>
+#include <ust/ustctl.h>
 
+#include "liblttsessiondcomm.h"
 #include "lttngerr.h"
 #include "trace.h"
 #include "session.h"
+#include "ltt-sessiond.h"
+
+static struct ltt_ust_trace *find_session_ust_trace_by_pid(
+               struct ltt_session *session, pid_t pid);
 
 /*
  *  find_session_ust_trace_by_pid
@@ -34,7 +40,8 @@
  *  Iterate over the session ust_traces and
  *  return a pointer or NULL if not found.
  */
-struct ltt_ust_trace *find_session_ust_trace_by_pid(struct ltt_session *session, pid_t pid)
+static struct ltt_ust_trace *find_session_ust_trace_by_pid(
+               struct ltt_session *session, pid_t pid)
 {
        struct ltt_ust_trace *iter;
 
@@ -56,7 +63,7 @@ struct ltt_ust_trace *find_session_ust_trace_by_pid(struct ltt_session *session,
  */
 int get_trace_count_per_session(struct ltt_session *session)
 {
-       return session->ust_trace_count + session->kern_trace_count;
+       return session->ust_trace_count + session->kern_session_count;
 }
 
 /*
@@ -69,7 +76,6 @@ void get_traces_per_session(struct ltt_session *session, struct lttng_trace *tra
 {
        int i = 0;
        struct ltt_ust_trace *ust_iter;
-       struct ltt_kernel_trace *kern_iter;
        struct lttng_trace trace;
 
        DBG("Getting userspace traces for session %s", session->name);
@@ -88,12 +94,122 @@ void get_traces_per_session(struct ltt_session *session, struct lttng_trace *tra
        DBG("Getting kernel traces for session %s", session->name);
 
        /* Getting kernel traces */
-       cds_list_for_each_entry(kern_iter, &session->kernel_traces, list) {
+       if (session->kern_session_count > 0) {
                trace.type = KERNEL;
-               strncpy(trace.name, kern_iter->name, sizeof(trace.name));
-               trace.name[sizeof(trace.name) - 1] = '\0';
+               strncpy(trace.name, "kernel", 6);
                memcpy(&traces[i], &trace, sizeof(trace));
-               memset(&trace, 0, sizeof(trace));
-               i++;
        }
 }
+
+/*
+ *  ust_create_trace
+ *
+ *  Create an userspace trace using pid.
+ *  This trace is then appended to the current session
+ *  ust trace list.
+ */
+int ust_create_trace(struct command_ctx *cmd_ctx)
+{
+       int ret;
+       struct ltt_ust_trace *trace;
+
+       DBG("Creating trace for pid %d", cmd_ctx->lsm->pid);
+
+       trace = malloc(sizeof(struct ltt_ust_trace));
+       if (trace == NULL) {
+               perror("malloc");
+               ret = -1;
+               goto error;
+       }
+
+       /* Init */
+       trace->pid = cmd_ctx->lsm->pid;
+       trace->shmid = 0;
+       /* NOTE: to be removed. Trace name will no longer be
+        * required for LTTng userspace tracer. For now, we set it
+        * to 'auto' for API compliance.
+        */
+       snprintf(trace->name, 5, "auto");
+
+       ret = ustctl_create_trace(cmd_ctx->ust_sock, trace->name);
+       if (ret < 0) {
+               ret = LTTCOMM_CREATE_FAIL;
+               goto error_create;
+       }
+
+       /* Check if current session is valid */
+       if (cmd_ctx->session) {
+               cds_list_add(&trace->list, &cmd_ctx->session->ust_traces);
+               cmd_ctx->session->ust_trace_count++;
+       }
+
+       return LTTCOMM_OK;
+
+error_create:
+       free(trace);
+error:
+       return ret;
+}
+
+/*
+ *  ust_start_trace
+ *
+ *  Start a trace. This trace, identified by the pid, must be
+ *  in the current session ust_traces list.
+ */
+int ust_start_trace(struct command_ctx *cmd_ctx)
+{
+       int ret;
+       struct ltt_ust_trace *trace;
+
+       DBG("Starting trace for pid %d", cmd_ctx->lsm->pid);
+
+       trace = find_session_ust_trace_by_pid(cmd_ctx->session, cmd_ctx->lsm->pid);
+       if (trace == NULL) {
+               ret = LTTCOMM_NO_TRACE;
+               goto error;
+       }
+
+       ret = ustctl_start_trace(cmd_ctx->ust_sock, "auto");
+       if (ret < 0) {
+               ret = LTTCOMM_START_FAIL;
+               goto error;
+       }
+
+       ret = LTTCOMM_OK;
+
+error:
+       return ret;
+}
+
+/*
+ *  ust_stop_trace
+ *
+ *  Stop a trace. This trace, identified by the pid, must be
+ *  in the current session ust_traces list.
+ */
+int ust_stop_trace(struct command_ctx *cmd_ctx)
+{
+       int ret;
+       struct ltt_ust_trace *trace;
+
+       DBG("Stopping trace for pid %d", cmd_ctx->lsm->pid);
+
+       trace = find_session_ust_trace_by_pid(cmd_ctx->session, cmd_ctx->lsm->pid);
+       if (trace == NULL) {
+               ret = LTTCOMM_NO_TRACE;
+               goto error;
+       }
+
+       ret = ustctl_stop_trace(cmd_ctx->ust_sock, trace->name);
+       if (ret < 0) {
+               ret = LTTCOMM_STOP_FAIL;
+               goto error;
+       }
+
+       ret = LTTCOMM_OK;
+
+error:
+       return ret;
+}
+