Commit-ID: a123c52b46a1f84bcec3dc963351896c6d6afaf7
Gitweb: http://git.kernel.org/tip/a123c52b46a1f84bcec3dc963351896c6d6afaf7
Author: Steven Rostedt <srostedt@xxxxxxxxxx>
AuthorDate: Thu, 12 Mar 2009 11:21:08 -0400
Commit: Steven Rostedt <srostedt@xxxxxxxxxx>
CommitDate: Thu, 12 Mar 2009 21:14:58 -0400
tracing: fix comments about trace buffer resizing
Impact: cleanup
Some of the comments about the trace buffer resizing is gobbledygook.
And I wonder why people question if I'm a native English speaker.
This patch makes the comments make a bit more sense.
Reported-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <srostedt@xxxxxxxxxx>
---
kernel/trace/trace.c | 19 ++++++++++++++++---
1 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c3946a6..c61ee85 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2336,7 +2336,8 @@ static int tracing_resize_ring_buffer(unsigned long size)
/*
* If kernel or user changes the size of the ring buffer
- * it get completed.
+ * we use the size that was given, and we can forget about
+ * expanding it later.
*/
ring_buffer_expanded = 1;
@@ -2351,8 +2352,20 @@ static int tracing_resize_ring_buffer(unsigned long size)
r = ring_buffer_resize(global_trace.buffer,
global_trace.entries);
if (r < 0) {
- /* AARGH! We are left with different
- * size max buffer!!!! */
+ /*
+ * AARGH! We are left with different
+ * size max buffer!!!!
+ * The max buffer is our "snapshot" buffer.
+ * When a tracer needs a snapshot (one of the
+ * latency tracers), it swaps the max buffer
+ * with the saved snap shot. We succeeded to
+ * update the size of the main buffer, but failed to
+ * update the size of the max buffer. But when we tried
+ * to reset the main buffer to the original size, we
+ * failed there too. This is very unlikely to
+ * happen, but if it does, warn and kill all
+ * tracing.
+ */
WARN_ON(1);
tracing_disabled = 1;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|