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authorSteven Rostedt <srostedt@redhat.com>2010-01-26 16:14:08 -0500
committerSteven Rostedt <rostedt@goodmis.org>2010-01-26 16:14:08 -0500
commit3c05d7482777f15e71bb4cb1ba78dee2800dfec6 (patch)
treecb3d7c935ede863ca94e0beb97dc57ceb1e75e7b
parent492a74f4210e15f4701422e2e1c4cd3c1e45ddae (diff)
downloadop-kernel-dev-3c05d7482777f15e71bb4cb1ba78dee2800dfec6.zip
op-kernel-dev-3c05d7482777f15e71bb4cb1ba78dee2800dfec6.tar.gz
ring-buffer: Check for end of page in iterator
If the iterator comes to an empty page for some reason, or if the page is emptied by a consuming read. The iterator code currently does not check if the iterator is pass the contents, and may return a false entry. This patch adds a check to the ring buffer iterator to test if the current page has been completely read and sets the iterator to the next page if necessary. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--kernel/trace/ring_buffer.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 503b630..8c1b2d2 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3064,9 +3064,6 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
struct ring_buffer_event *event;
int nr_loops = 0;
- if (ring_buffer_iter_empty(iter))
- return NULL;
-
cpu_buffer = iter->cpu_buffer;
buffer = cpu_buffer->buffer;
@@ -3080,6 +3077,9 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
rb_iter_reset(iter);
again:
+ if (ring_buffer_iter_empty(iter))
+ return NULL;
+
/*
* We repeat when a timestamp is encountered.
* We can get multiple timestamps by nested interrupts or also
@@ -3094,6 +3094,11 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
if (rb_per_cpu_empty(cpu_buffer))
return NULL;
+ if (iter->head >= local_read(&iter->head_page->page->commit)) {
+ rb_inc_iter(iter);
+ goto again;
+ }
+
event = rb_iter_head_event(iter);
switch (event->type_len) {
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