linux-kernel - [PATCH][GIT PULL] ftrace: Using FTRACE_WARN_ON() to check "freed record" in ftrace

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Date:	Wed, 25 Mar 2009 19:04:29 -0400 (EDT)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	LKML <linux-kernel@...r.kernel.org>
cc:	Ingo Molnar <mingo@...e.hu>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Zhaolei <zhaolei@...fujitsu.com>
Subject: [PATCH][GIT PULL] ftrace: Using FTRACE_WARN_ON() to check "freed
 record" in ftrace_release()


Ingo,

Please pull the latest tip/tracing/ftrace-1 tree, which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
tip/tracing/ftrace-1


Zhaolei (1):
      ftrace: Using FTRACE_WARN_ON() to check "freed record" in ftrace_release()

----
 kernel/trace/ftrace.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)
---------------------------
commit 2a4efa42450762cbfa5c5712aa4cc9f06924c9fd
Author: Zhaolei <zhaolei@...fujitsu.com>
Date:   Wed Mar 25 12:06:05 2009 +0800

    ftrace: Using FTRACE_WARN_ON() to check "freed record" in ftrace_release()
    
     "Because when we call ftrace_free_rec we change the rec->ip to point to the
      next record in the chain. Something is very wrong if rec->ip >= s &&
      rec->ip < e and the record is already free."
    
     "Note, use FTRACE_WARN_ON() macro. This way it shuts down ftrace if it is
      hit and helps to avoid further damage later."
                       -- Steven Rostedt <rostedt@...dmis.org>
    
    Signed-off-by: Zhao Lei <zhaolei@...fujitsu.com>
    Signed-off-by: Steven Rostedt <srostedt@...hat.com>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7b8722b..1752a63 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -358,9 +358,14 @@ void ftrace_release(void *start, unsigned long size)
 
 	mutex_lock(&ftrace_lock);
 	do_for_each_ftrace_rec(pg, rec) {
-		if ((rec->ip >= s) && (rec->ip < e) &&
-		    !(rec->flags & FTRACE_FL_FREE))
+		if ((rec->ip >= s) && (rec->ip < e)) {
+			/*
+			 * rec->ip is changed in ftrace_free_rec()
+			 * It should not between s and e if record was freed.
+			 */
+			FTRACE_WARN_ON(rec->flags & FTRACE_FL_FREE);
 			ftrace_free_rec(rec);
+		}
 	} while_for_each_ftrace_rec();
 	mutex_unlock(&ftrace_lock);
 }

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