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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: Lai 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: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Lai Jiangshan 2009-04-02 15:16:59 +08:00 committed by Ingo Molnar
parent d1e7e02f30
commit ddd538f3e6
1 changed files with 8 additions and 8 deletions
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16
kernel/trace/trace.c
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@ -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;
@ -3342,7 +3341,8 @@ static int tracing_buffers_release(struct inode *inode, struct file *file)
{
struct ftrace_buffer_info *info = file->private_data;
ring_buffer_free_read_page(info->tr->buffer, info->spare);
if (info->spare)
ring_buffer_free_read_page(info->tr->buffer, info->spare);
kfree(info);
return 0;