linux-kernel - [PATCH v2] ftrace: Do not copy old hash when resetting.

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Message-ID: <1405384820-48837-1-git-send-email-wangnan0@huawei.com>
Date:	Tue, 15 Jul 2014 08:40:20 +0800
From:	Wang Nan <wangnan0@...wei.com>
To:	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...hat.com>
CC:	<linux-kernel@...r.kernel.org>, <peifeiyue@...wei.com>
Subject: [PATCH v2] ftrace: Do not copy old hash when resetting.

If we are going to reset hash, we don't need to duplicate old hash
and remove every entries right after allocation.

Change from v1:
 - if statement is swapped to make condition positive.

Signed-off-by: Wang Nan <wangnan0@...wei.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Ingo Molnar <mingo@...hat.com>

---
 kernel/trace/ftrace.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 5b372e3..aa61d01 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3471,14 +3471,16 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
 	else
 		orig_hash = &ops->notrace_hash;
 
-	hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
+	if (reset)
+		hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
+	else
+		hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
+
 	if (!hash) {
 		ret = -ENOMEM;
 		goto out_regex_unlock;
 	}
 
-	if (reset)
-		ftrace_filter_reset(hash);
 	if (buf && !ftrace_match_records(hash, buf, len)) {
 		ret = -EINVAL;
 		goto out_regex_unlock;
-- 
1.8.4

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