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authorDavid Sharp <dhsharp@google.com>2012-10-12 03:27:52 +0400
committerSteven Rostedt <rostedt@goodmis.org>2012-11-02 18:21:47 +0400
commit60303ed3f4b9332b9aa9bc17c68bc174e7343e2d (patch)
tree1d9a7c8001297aafda1e873884dd8bda5aaf7872
parent60efc15ae96c7aace8060411b0d5add20e1ab21e (diff)
downloadlinux-60303ed3f4b9332b9aa9bc17c68bc174e7343e2d.tar.xz
tracing: Reset ring buffer when changing trace_clocks
Because the "tsc" clock isn't in nanoseconds, the ring buffer must be reset when changing clocks so that incomparable timestamps don't end up in the same trace. Tested: Confirmed switching clocks resets the trace buffer. Google-Bug-Id: 6980623 Link: http://lkml.kernel.org/r/1349998076-15495-3-git-send-email-dhsharp@google.com Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: David Sharp <dhsharp@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--kernel/trace/trace.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 88111b08b2c1..6ed6013dff2b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4073,6 +4073,14 @@ static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
if (max_tr.buffer)
ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func);
+ /*
+ * New clock may not be consistent with the previous clock.
+ * Reset the buffer so that it doesn't have incomparable timestamps.
+ */
+ tracing_reset_online_cpus(&global_trace);
+ if (max_tr.buffer)
+ tracing_reset_online_cpus(&max_tr);
+
mutex_unlock(&trace_types_lock);
*fpos += cnt;