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author | Steven Rostedt <srostedt@redhat.com> | 2008-12-02 15:34:07 -0500 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-12-03 08:56:21 +0100 |
commit | 8789a9e7df6bf9b93739c4c7d4e380725bc9e936 (patch) | |
tree | 0930b286d987611b4a453766e8479bb005edbc27 /include/linux/ring_buffer.h | |
parent | abc9b56d66fbd4d93302ef4bf6fa726e1b8255f9 (diff) | |
download | linux-stable-8789a9e7df6bf9b93739c4c7d4e380725bc9e936.tar.gz linux-stable-8789a9e7df6bf9b93739c4c7d4e380725bc9e936.tar.bz2 linux-stable-8789a9e7df6bf9b93739c4c7d4e380725bc9e936.zip |
ring-buffer: read page interface
Impact: new API to ring buffer
This patch adds a new interface into the ring buffer that allows a
page to be read from the ring buffer on a given CPU. For every page
read, one must also be given to allow for a "swap" of the pages.
rpage = ring_buffer_alloc_read_page(buffer);
if (!rpage)
goto err;
ret = ring_buffer_read_page(buffer, &rpage, cpu, full);
if (!ret)
goto empty;
process_page(rpage);
ring_buffer_free_read_page(rpage);
The caller of these functions must handle any waits that are
needed to wait for new data. The ring_buffer_read_page will simply
return 0 if there is no data, or if "full" is set and the writer
is still on the current page.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/ring_buffer.h')
-rw-r--r-- | include/linux/ring_buffer.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 3bb87a753fa3..1a350a847edd 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -124,6 +124,11 @@ void tracing_on(void); void tracing_off(void); void tracing_off_permanent(void); +void *ring_buffer_alloc_read_page(struct ring_buffer *buffer); +void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data); +int ring_buffer_read_page(struct ring_buffer *buffer, + void **data_page, int cpu, int full); + enum ring_buffer_flags { RB_FL_OVERWRITE = 1 << 0, }; |