From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 14 Jul 2011 18:09:09 +0000 (-0400)
Subject: Check if channel has closed stream in channel poll for CPU hotplug
X-Git-Tag: v2.0-pre1~24
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=f71ecafa46ad2ba9998ba6e4c425645d988d7f8c;p=lttng-modules.git

Check if channel has closed stream in channel poll for CPU hotplug

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/ltt-debugfs-abi.c b/ltt-debugfs-abi.c
index 0aa2cec0..72077183 100644
--- a/ltt-debugfs-abi.c
+++ b/ltt-debugfs-abi.c
@@ -609,8 +609,9 @@ unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 			return POLLERR;
 		if (channel->ops->is_finalized(channel->chan))
 			return POLLHUP;
-		else
+		if (channel->ops->buffer_has_read_closed_stream(channel->chan))
 			return POLLIN | POLLRDNORM;
+		return 0;
 	}
 	return mask;
 
diff --git a/ltt-events.h b/ltt-events.h
index 1307c36b..304bcb69 100644
--- a/ltt-events.h
+++ b/ltt-events.h
@@ -191,6 +191,7 @@ struct ltt_channel_ops {
 				unsigned int read_timer_interval);
 	void (*channel_destroy)(struct channel *chan);
 	struct lib_ring_buffer *(*buffer_read_open)(struct channel *chan);
+	int (*buffer_has_read_closed_stream)(struct channel *chan);
 	void (*buffer_read_close)(struct lib_ring_buffer *buf);
 	int (*event_reserve)(struct lib_ring_buffer_ctx *ctx,
 			     uint32_t event_id);
diff --git a/ltt-ring-buffer-client.h b/ltt-ring-buffer-client.h
index 39587dd0..25152bf3 100644
--- a/ltt-ring-buffer-client.h
+++ b/ltt-ring-buffer-client.h
@@ -399,6 +399,20 @@ struct lib_ring_buffer *ltt_buffer_read_open(struct channel *chan)
 	return NULL;
 }
 
+static
+int ltt_buffer_has_read_closed_stream(struct channel *chan)
+{
+	struct lib_ring_buffer *buf;
+	int cpu;
+
+	for_each_channel_cpu(cpu, chan) {
+		buf = channel_get_ring_buffer(&client_config, chan, cpu);
+		if (!atomic_long_read(&buf->active_readers))
+			return 1;
+	}
+	return 0;
+}
+
 static
 void ltt_buffer_read_close(struct lib_ring_buffer *buf)
 {
@@ -485,6 +499,8 @@ static struct ltt_transport ltt_relay_transport = {
 		.channel_create = _channel_create,
 		.channel_destroy = ltt_channel_destroy,
 		.buffer_read_open = ltt_buffer_read_open,
+		.buffer_has_read_closed_stream =
+			ltt_buffer_has_read_closed_stream,
 		.buffer_read_close = ltt_buffer_read_close,
 		.event_reserve = ltt_event_reserve,
 		.event_commit = ltt_event_commit,
diff --git a/ltt-ring-buffer-metadata-client.h b/ltt-ring-buffer-metadata-client.h
index 43a711ca..06936aaa 100644
--- a/ltt-ring-buffer-metadata-client.h
+++ b/ltt-ring-buffer-metadata-client.h
@@ -177,6 +177,20 @@ struct lib_ring_buffer *ltt_buffer_read_open(struct channel *chan)
 	return NULL;
 }
 
+static
+int ltt_buffer_has_read_closed_stream(struct channel *chan)
+{
+	struct lib_ring_buffer *buf;
+	int cpu;
+
+	for_each_channel_cpu(cpu, chan) {
+		buf = channel_get_ring_buffer(&client_config, chan, cpu);
+		if (!atomic_long_read(&buf->active_readers))
+			return 1;
+	}
+	return 0;
+}
+
 static
 void ltt_buffer_read_close(struct lib_ring_buffer *buf)
 {
@@ -250,6 +264,8 @@ static struct ltt_transport ltt_relay_transport = {
 		.channel_create = _channel_create,
 		.channel_destroy = ltt_channel_destroy,
 		.buffer_read_open = ltt_buffer_read_open,
+		.buffer_has_read_closed_stream =
+			ltt_buffer_has_read_closed_stream,
 		.buffer_read_close = ltt_buffer_read_close,
 		.event_reserve = ltt_event_reserve,
 		.event_commit = ltt_event_commit,