lkml.org 
[lkml]   [2009]   [Feb]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 1/2] ring_buffer: fix typing mistake

Impact: Fix bug

I found several very very curious line.
It's so curious that it may be brought by typing mistake.

When (cpu_buffer->reader_page == cpu_buffer->commit_page):

1) We haven't copied it for bpage is changed:
bpage = cpu_buffer->reader_page->page;
memcpy(bpage->data, cpu_buffer->reader_page->page->data + read ... )
2) We need update cpu_buffer->reader_page->read, but
"cpu_buffer->reader_page += read;" is not right.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
ring_buffer.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index bd38c5c..e97acae 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2377,7 +2377,7 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data)
* to swap with a page in the ring buffer.
*
* for example:
- * rpage = ring_buffer_alloc_page(buffer);
+ * rpage = ring_buffer_alloc_read_page(buffer);
* if (!rpage)
* return error;
* ret = ring_buffer_read_page(buffer, &rpage, cpu, 0);
@@ -2432,18 +2432,17 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
*/
if (cpu_buffer->reader_page == cpu_buffer->commit_page) {
unsigned int read = cpu_buffer->reader_page->read;
+ unsigned int commit = rb_page_commit(cpu_buffer->reader_page);

if (full)
goto out;
/* The writer is still on the reader page, we must copy */
- bpage = cpu_buffer->reader_page->page;
memcpy(bpage->data,
cpu_buffer->reader_page->page->data + read,
- local_read(&bpage->commit) - read);
+ commit - read);

/* consume what was read */
- cpu_buffer->reader_page += read;
-
+ cpu_buffer->reader_page->read = commit;
} else {
/* swap the pages */
rb_init_page(bpage);




\
 
 \ /
  Last update: 2009-02-09 07:23    [W:0.029 / U:0.252 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site