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Commit ddd538f3 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Ingo Molnar
Browse files

tracing: allocate page when needed 



Impact: Cleanup

Sometimes, we open trace_pipe_raw, but we don't read(2) it,
we just splice(2) it, thus, the page is not used.

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D4666B.4010608@cn.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d1e7e02f

kernel/trace/trace.c

+8 −8
Original line number Diff line number Diff line
@@ -3277,19 +3277,13 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp) 


	info->tr	= &global_trace;

	info->cpu	= cpu;

	info->spare	= ring_buffer_alloc_read_page(info->tr->buffer);

	info->spare	= NULL;

	/* Force reading ring buffer for first read */

	info->read	= (unsigned int)-1;

	if (!info->spare)

		goto out;



	filp->private_data = info;



	return nonseekable_open(inode, filp);



 out:

	kfree(info);

	return -ENOMEM;

}



static ssize_t
@@ -3304,6 +3298,11 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, 
	if (!count)

		return 0;



	if (!info->spare)

		info->spare = ring_buffer_alloc_read_page(info->tr->buffer);

	if (!info->spare)

		return -ENOMEM;



	/* Do we have previous read data to read? */

	if (info->read < PAGE_SIZE)

		goto read;
@@ -3342,6 +3341,7 @@ static int tracing_buffers_release(struct inode *inode, struct file *file) 
{

	struct ftrace_buffer_info *info = file->private_data;



	if (info->spare)

		ring_buffer_free_read_page(info->tr->buffer, info->spare);

	kfree(info);