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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>
This commit is contained in:
Steven Rostedt 2010-01-26 16:14:08 -05:00 committed by Steven Rostedt
parent 492a74f421
commit 3c05d74827
1 changed files with 8 additions and 3 deletions
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11
kernel/trace/ring_buffer.c
View File

@ -3064,9 +3064,6 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
struct ring_buffer_event *event; struct ring_buffer_event *event;
int nr_loops = 0; int nr_loops = 0;
if (ring_buffer_iter_empty(iter))
return NULL;
cpu_buffer = iter->cpu_buffer; cpu_buffer = iter->cpu_buffer;
buffer = cpu_buffer->buffer; buffer = cpu_buffer->buffer;
@ -3080,6 +3077,9 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
rb_iter_reset(iter); rb_iter_reset(iter);
again: again:
if (ring_buffer_iter_empty(iter))
return NULL;
/* /*
* We repeat when a timestamp is encountered. * We repeat when a timestamp is encountered.
* We can get multiple timestamps by nested interrupts or also * 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)) if (rb_per_cpu_empty(cpu_buffer))
return NULL; return NULL;
if (iter->head >= local_read(&iter->head_page->page->commit)) {
rb_inc_iter(iter);
goto again;
}
event = rb_iter_head_event(iter); event = rb_iter_head_event(iter);
switch (event->type_len) { switch (event->type_len) {