From: David Goulet <david.goulet@polymtl.ca>
Date: Wed, 29 Jun 2011 17:27:09 +0000 (-0400)
Subject: Add enable kernel event using the enable ioctl
X-Git-Tag: v2.0-pre1~72
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=19e708528b7ebd740485ca05056e56e6835d43a7;p=lttng-tools.git

Add enable kernel event using the enable ioctl

Two helper functions are added which are get an event by name and a
channel by name.

The disable and enable event command was modified to use these two
functions.

Overall, it's now possible to enable/disable at will kernel events.

Signed-off-by: David Goulet <david.goulet@polymtl.ca>
---

diff --git a/ltt-sessiond/kernel-ctl.c b/ltt-sessiond/kernel-ctl.c
index 2f1864d64..16b85bdb5 100644
--- a/ltt-sessiond/kernel-ctl.c
+++ b/ltt-sessiond/kernel-ctl.c
@@ -124,7 +124,7 @@ error:
  *  Create a kernel event, enable it to the kernel tracer and add it to the
  *  channel event list of the kernel session.
  */
-int kernel_create_event(struct ltt_kernel_channel *channel, struct lttng_event *ev)
+int kernel_create_event(struct lttng_event *ev, struct ltt_kernel_channel *channel)
 {
 	int ret;
 	struct ltt_kernel_event *event;
@@ -161,29 +161,47 @@ error:
 }
 
 /*
- *  kernel_disable_event
+ *  kernel_enable_event
  *
- *  Disable a kernel event for a specific channel.
+ *  Enable a kernel event.
  */
-int kernel_disable_event(char *event_name, struct ltt_kernel_channel *channel)
+int kernel_enable_event(struct ltt_kernel_event *event)
 {
 	int ret;
-	struct ltt_kernel_event *iter;
 
-	cds_list_for_each_entry(iter, &channel->events_list.head, list) {
-		if (strcmp(iter->event->name, event_name) == 0) {
-			ret = kernctl_disable(iter->fd);
-			if (ret < 0) {
-				perror("disable event ioctl");
-				goto error;
-			}
+	ret = kernctl_enable(event->fd);
+	if (ret < 0) {
+		perror("enable event ioctl");
+		goto error;
+	}
 
-			iter->enabled = 0;
-			DBG("Kernel event %s disabled (fd: %d)", iter->event->name, iter->fd);
-			break;
-		}
+	event->enabled = 1;
+	DBG("Kernel event %s enabled (fd: %d)", event->event->name, event->fd);
+
+	return 0;
+
+error:
+	return -1;
+}
+
+/*
+ *  kernel_disable_event
+ *
+ *  Disable a kernel event.
+ */
+int kernel_disable_event(struct ltt_kernel_event *event)
+{
+	int ret;
+
+	ret = kernctl_disable(event->fd);
+	if (ret < 0) {
+		perror("disable event ioctl");
+		goto error;
 	}
 
+	event->enabled = 0;
+	DBG("Kernel event %s disabled (fd: %d)", event->event->name, event->fd);
+
 	return 0;
 
 error:
diff --git a/ltt-sessiond/kernel-ctl.h b/ltt-sessiond/kernel-ctl.h
index adc930d1c..d36cd6d10 100644
--- a/ltt-sessiond/kernel-ctl.h
+++ b/ltt-sessiond/kernel-ctl.h
@@ -32,8 +32,9 @@
 
 int kernel_create_session(struct ltt_session *session, int tracer_fd);
 int kernel_create_channel(struct ltt_kernel_session *session, struct lttng_channel *chan);
-int kernel_create_event(struct ltt_kernel_channel *channel, struct lttng_event *ev);
-int kernel_disable_event(char *event_name, struct ltt_kernel_channel *channel);
+int kernel_create_event(struct lttng_event *ev, struct ltt_kernel_channel *channel);
+int kernel_disable_event(struct ltt_kernel_event *event);
+int kernel_enable_event(struct ltt_kernel_event *event);
 int kernel_open_metadata(struct ltt_kernel_session *session);
 int kernel_open_metadata_stream(struct ltt_kernel_session *session);
 int kernel_open_channel_stream(struct ltt_kernel_channel *channel);
diff --git a/ltt-sessiond/main.c b/ltt-sessiond/main.c
index 4da3caba0..5a8119f91 100644
--- a/ltt-sessiond/main.c
+++ b/ltt-sessiond/main.c
@@ -875,8 +875,8 @@ static int process_client_msg(struct command_ctx *cmd_ctx)
 	}
 	case LTTNG_KERNEL_DISABLE_EVENT:
 	{
-		int found = 0;
 		struct ltt_kernel_channel *chan;
+		struct ltt_kernel_event *ev;
 
 		/* Setup lttng message with no payload */
 		ret = setup_lttng_msg(cmd_ctx, 0);
@@ -884,34 +884,32 @@ static int process_client_msg(struct command_ctx *cmd_ctx)
 			goto setup_error;
 		}
 
-		/* Get channel by name and create event for that channel */
-		cds_list_for_each_entry(chan, &cmd_ctx->session->kernel_session->channel_list.head, list) {
-			if (strcmp(cmd_ctx->lsm->u.disable.channel_name, chan->channel->name) == 0) {
-				DBG("Disabling kernel event %s for channel %s.",
-						cmd_ctx->lsm->u.disable.name, cmd_ctx->lsm->u.disable.channel_name);
+		chan = get_kernel_channel_by_name(cmd_ctx->lsm->u.disable.channel_name,
+				cmd_ctx->session->kernel_session);
+		if (chan == NULL) {
+			ret = LTTCOMM_KERN_CHAN_NOT_FOUND;
+			goto error;
+		}
 
-				ret = kernel_disable_event(cmd_ctx->lsm->u.disable.name, chan);
-				if (ret < 0) {
-					ret = LTTCOMM_KERN_DISABLE_FAIL;
-					goto error;
-				}
-				found = 1;
-				break;
+		ev = get_kernel_event_by_name(cmd_ctx->lsm->u.disable.name, chan);
+		if (ev != NULL) {
+			DBG("Disabling kernel event %s for channel %s.",
+					cmd_ctx->lsm->u.disable.name, cmd_ctx->lsm->u.disable.channel_name);
+			ret = kernel_disable_event(ev);
+			if (ret < 0) {
+				ret = LTTCOMM_KERN_ENABLE_FAIL;
+				goto error;
 			}
 		}
 
-		if (!found) {
-			ret = LTTCOMM_KERN_CHAN_NOT_FOUND;
-		} else {
-			kernel_wait_quiescent(kernel_tracer_fd);
-			ret = LTTCOMM_OK;
-		}
+		kernel_wait_quiescent(kernel_tracer_fd);
+		ret = LTTCOMM_OK;
 		break;
 	}
 	case LTTNG_KERNEL_ENABLE_EVENT:
 	{
-		int found = 0;
 		struct ltt_kernel_channel *chan;
+		struct ltt_kernel_event *ev;
 
 		/* Setup lttng message with no payload */
 		ret = setup_lttng_msg(cmd_ctx, 0);
@@ -919,28 +917,31 @@ static int process_client_msg(struct command_ctx *cmd_ctx)
 			goto setup_error;
 		}
 
-		/* Get channel by name and create event for that channel */
-		cds_list_for_each_entry(chan, &cmd_ctx->session->kernel_session->channel_list.head, list) {
-			if (strcmp(cmd_ctx->lsm->u.enable.channel_name, chan->channel->name) == 0) {
-				DBG("Creating kernel event %s for channel %s.",
-						cmd_ctx->lsm->u.enable.event.name, cmd_ctx->lsm->u.enable.channel_name);
-
-				ret = kernel_create_event(chan, &cmd_ctx->lsm->u.enable.event);
-				if (ret < 0) {
-					ret = LTTCOMM_KERN_ENABLE_FAIL;
-					goto error;
-				}
-				found = 1;
-				break;
-			}
+		chan = get_kernel_channel_by_name(cmd_ctx->lsm->u.enable.channel_name,
+				cmd_ctx->session->kernel_session);
+		if (chan == NULL) {
+			ret = LTTCOMM_KERN_CHAN_NOT_FOUND;
+			goto error;
 		}
 
-		if (!found) {
-			ret = LTTCOMM_KERN_CHAN_NOT_FOUND;
+		ev = get_kernel_event_by_name(cmd_ctx->lsm->u.enable.event.name, chan);
+		if (ev == NULL) {
+			DBG("Creating kernel event %s for channel %s.",
+					cmd_ctx->lsm->u.enable.event.name, cmd_ctx->lsm->u.enable.channel_name);
+			ret = kernel_create_event(&cmd_ctx->lsm->u.enable.event, chan);
 		} else {
-			kernel_wait_quiescent(kernel_tracer_fd);
-			ret = LTTCOMM_OK;
+			DBG("Enabling kernel event %s for channel %s.",
+					cmd_ctx->lsm->u.enable.event.name, cmd_ctx->lsm->u.enable.channel_name);
+			ret = kernel_enable_event(ev);
+		}
+
+		if (ret < 0) {
+			ret = LTTCOMM_KERN_ENABLE_FAIL;
+			goto error;
 		}
+
+		kernel_wait_quiescent(kernel_tracer_fd);
+		ret = LTTCOMM_OK;
 		break;
 	}
 	case LTTNG_KERNEL_ENABLE_ALL_EVENT:
@@ -983,7 +984,7 @@ static int process_client_msg(struct command_ctx *cmd_ctx)
 			/* Default event type for enable all */
 			ev.type = LTTNG_EVENT_TRACEPOINTS;
 			/* Enable each single tracepoint event */
-			ret = kernel_create_event(chan, &ev);
+			ret = kernel_create_event(&ev, chan);
 			if (ret < 0) {
 				ret = LTTCOMM_KERN_ENABLE_FAIL;
 				goto error;
diff --git a/ltt-sessiond/trace.c b/ltt-sessiond/trace.c
index e0051cd1c..eb7d0e152 100644
--- a/ltt-sessiond/trace.c
+++ b/ltt-sessiond/trace.c
@@ -27,6 +27,59 @@
 #include "ltt-sessiond.h"
 #include "trace.h"
 
+/*
+ *  get_kernel_channel_by_name
+ *
+ *  Find the channel name for the given kernel session.
+ */
+struct ltt_kernel_channel *get_kernel_channel_by_name(
+		char *name, struct ltt_kernel_session *session)
+{
+	struct ltt_kernel_channel *chan;
+
+	if (session == NULL) {
+		ERR("Undefine session");
+		goto error;
+	}
+
+	cds_list_for_each_entry(chan, &session->channel_list.head, list) {
+		if (strcmp(name, chan->channel->name) == 0) {
+			DBG("Found channel by name %s", name);
+			return chan;
+		}
+	}
+
+error:
+	return NULL;
+}
+
+/*
+ *  get_kernel_event_by_name
+ *
+ *  Find the event name for the given channel.
+ */
+struct ltt_kernel_event *get_kernel_event_by_name(
+		char *name, struct ltt_kernel_channel *channel)
+{
+	struct ltt_kernel_event *ev;
+
+	if (channel == NULL) {
+		ERR("Undefine channel");
+		goto error;
+	}
+
+	cds_list_for_each_entry(ev, &channel->events_list.head, list) {
+		if (strcmp(name, ev->event->name) == 0) {
+			DBG("Found event by name %s for channel %s", name,
+					channel->channel->name);
+			return ev;
+		}
+	}
+
+error:
+	return NULL;
+}
+
 /*
  *  trace_create_kernel_session
  *
diff --git a/ltt-sessiond/trace.h b/ltt-sessiond/trace.h
index 8da147230..427b05b88 100644
--- a/ltt-sessiond/trace.h
+++ b/ltt-sessiond/trace.h
@@ -101,6 +101,14 @@ struct ltt_ust_marker {
 	char *channel;
 };
 
+/*
+ * Get functions.
+ */
+struct ltt_kernel_event *get_kernel_event_by_name(
+		char *name, struct ltt_kernel_channel *channel);
+struct ltt_kernel_channel *get_kernel_channel_by_name(
+		char *name, struct ltt_kernel_session *session);
+
 /*
  * Create functions malloc() the data structure.
  */