[PATCH 2/2] tracing/urgent: warn in case of ftrace_start_up inbalance

From: Frederic Weisbecker
Date: Sat Jun 20 2009 - 01:06:37 EST


Prevent from further ftrace_start_up inbalances so that we avoid
future nop patching omissions with dynamic ftrace.

Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
kernel/trace/ftrace.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index bb60732..3718d55 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1224,6 +1224,13 @@ static void ftrace_shutdown(int command)
return;

ftrace_start_up--;
+ /*
+ * Just warn in case of unbalance, no need to kill ftrace, it's not
+ * critical but the ftrace_call callers may be never nopped again after
+ * further ftrace uses.
+ */
+ WARN_ON_ONCE(ftrace_start_up < 0);
+
if (!ftrace_start_up)
command |= FTRACE_DISABLE_CALLS;

--
1.6.2.3

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