1 files changed, 44 insertions, 33 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 61e081b4ba11..3c13e46d7d24 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2899,6 +2899,8 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 	if (copy_from_user(&buf, ubuf, cnt))
 		return -EFAULT;
 
+	buf[cnt] = 0;
+
 	trace_set_options(buf);
 
 	*ppos += cnt;
@@ -3034,6 +3036,31 @@ static void set_buffer_entries(struct trace_array *tr, unsigned long val)
 		tr->data[cpu]->entries = val;
 }
 
+/* resize @tr's buffer to the size of @size_tr's entries */
+static int resize_buffer_duplicate_size(struct trace_array *tr,
+					struct trace_array *size_tr, int cpu_id)
+{
+	int cpu, ret = 0;
+
+	if (cpu_id == RING_BUFFER_ALL_CPUS) {
+		for_each_tracing_cpu(cpu) {
+			ret = ring_buffer_resize(tr->buffer,
+					size_tr->data[cpu]->entries, cpu);
+			if (ret < 0)
+				break;
+			tr->data[cpu]->entries = size_tr->data[cpu]->entries;
+		}
+	} else {
+		ret = ring_buffer_resize(tr->buffer,
+					size_tr->data[cpu_id]->entries, cpu_id);
+		if (ret == 0)
+			tr->data[cpu_id]->entries =
+				size_tr->data[cpu_id]->entries;
+	}
+
+	return ret;
+}
+
 static int __tracing_resize_ring_buffer(unsigned long size, int cpu)
 {
 	int ret;
@@ -3058,23 +3085,8 @@ static int __tracing_resize_ring_buffer(unsigned long size, int cpu)
 
 	ret = ring_buffer_resize(max_tr.buffer, size, cpu);
 	if (ret < 0) {
-		int r = 0;
-
-		if (cpu == RING_BUFFER_ALL_CPUS) {
-			int i;
-			for_each_tracing_cpu(i) {
-				r = ring_buffer_resize(global_trace.buffer,
-						global_trace.data[i]->entries,
-						i);
-				if (r < 0)
-					break;
-			}
-		} else {
-			r = ring_buffer_resize(global_trace.buffer,
-						global_trace.data[cpu]->entries,
-						cpu);
-		}
-
+		int r = resize_buffer_duplicate_size(&global_trace,
+						     &global_trace, cpu);
 		if (r < 0) {
 			/*
 			 * AARGH! We are left with different
@@ -3212,17 +3224,11 @@ static int tracing_set_tracer(const char *buf)
 
 	topts = create_trace_option_files(t);
 	if (t->use_max_tr) {
-		int cpu;
 		/* we need to make per cpu buffer sizes equivalent */
-		for_each_tracing_cpu(cpu) {
-			ret = ring_buffer_resize(max_tr.buffer,
-						global_trace.data[cpu]->entries,
-						cpu);
-			if (ret < 0)
-				goto out;
-			max_tr.data[cpu]->entries =
-					global_trace.data[cpu]->entries;
-		}
+		ret = resize_buffer_duplicate_size(&max_tr, &global_trace,
+						   RING_BUFFER_ALL_CPUS);
+		if (ret < 0)
+			goto out;
 	}
 
 	if (t->init) {
@@ -3448,7 +3454,7 @@ static int tracing_wait_pipe(struct file *filp)
 			return -EINTR;
 
 		/*
-		 * We block until we read something and tracing is enabled.
+		 * We block until we read something and tracing is disabled.
 		 * We still block if tracing is disabled, but we have never
 		 * read anything. This allows a user to cat this file, and
 		 * then enable tracing. But after we have read something,
@@ -3456,7 +3462,7 @@ static int tracing_wait_pipe(struct file *filp)
 		 *
 		 * iter->pos will be 0 if we haven't read anything.
 		 */
-		if (tracing_is_enabled() && iter->pos)
+		if (!tracing_is_enabled() && iter->pos)
 			break;
 	}
 
@@ -4271,13 +4277,11 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 		return -ENOMEM;
 
 	if (*ppos & (PAGE_SIZE - 1)) {
-		WARN_ONCE(1, "Ftrace: previous read must page-align\n");
 		ret = -EINVAL;
 		goto out;
 	}
 
 	if (len & (PAGE_SIZE - 1)) {
-		WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
 		if (len < PAGE_SIZE) {
 			ret = -EINVAL;
 			goto out;
@@ -4813,10 +4817,17 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
 		return ret;
 
 	if (buffer) {
-		if (val)
+		mutex_lock(&trace_types_lock);
+		if (val) {
 			ring_buffer_record_on(buffer);
-		else
+			if (current_trace->start)
+				current_trace->start(tr);
+		} else {
 			ring_buffer_record_off(buffer);
+			if (current_trace->stop)
+				current_trace->stop(tr);
+		}
+		mutex_unlock(&trace_types_lock);
 	}
 
 	(*ppos)++;