linux-kernel - Re: [PATCH 0/4] ftrace: prevent ftrace modifications while being kprobe'd

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Date:	Thu, 26 Jun 2008 22:51:51 +0530
From:	Abhishek Sagar <sagar.abhishek@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/4] ftrace: prevent ftrace modifications while being
 kprobe'd

Ingo Molnar wrote:
> best would be a delta patch against tip/master to fix up whatever is 
> still missing.

Here is the merge fixup for tip/master (and tip/tracing/ftrace).

Signed-off-by: Abhishek Sagar <sagar.abhishek@...il.com>
---

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 85e8413..0f271c4 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -502,8 +502,12 @@ static void ftrace_replace_code(int enable)
 				continue;
 
 			/* ignore updates to this record's mcount site */
-			if (get_kprobe((void *)rec->ip))
+			if (get_kprobe((void *)rec->ip)) {
+				freeze_record(rec);
 				continue;
+			} else {
+				unfreeze_record(rec);
+			}
 
 			failed = __ftrace_replace_code(rec, old, new, enable);
 			if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
@@ -740,7 +744,10 @@ static int __ftrace_update_code(void *ignore)
 				ftrace_del_hash(p);
 				INIT_HLIST_NODE(&p->node);
 				hlist_add_head(&p->node, &temp_list);
+				freeze_record(p);
 				continue;
+			} else {
+				unfreeze_record(p);
 			}
 
 			/* convert record (i.e, patch mcount-call with NOP) */
--
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