linux-kernel - [PATCH v2] ftrace: simplify ftrace hash lookup code

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Date:   Mon,  9 Sep 2019 08:31:59 +0800
From:   Changbin Du <changbin.du@...il.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        Changbin Du <changbin.du@...il.com>
Subject: [PATCH v2] ftrace: simplify ftrace hash lookup code

Function ftrace_lookup_ip() will check empty hash table. So we don't
need extra check outside.

Signed-off-by: Changbin Du <changbin.du@...il.com>

---
v2: fix incorrect code remove.
---
 kernel/trace/ftrace.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f9821a3374e9..92aab854d3b1 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1463,8 +1463,7 @@ static bool hash_contains_ip(unsigned long ip,
 	 */
 	return (ftrace_hash_empty(hash->filter_hash) ||
 		__ftrace_lookup_ip(hash->filter_hash, ip)) &&
-		(ftrace_hash_empty(hash->notrace_hash) ||
-		 !__ftrace_lookup_ip(hash->notrace_hash, ip));
+	       !ftrace_lookup_ip(hash->notrace_hash, ip);
 }
 
 /*
@@ -6036,11 +6035,7 @@ clear_func_from_hash(struct ftrace_init_func *func, struct ftrace_hash *hash)
 {
 	struct ftrace_func_entry *entry;
 
-	if (ftrace_hash_empty(hash))
-		return;
-
-	entry = __ftrace_lookup_ip(hash, func->ip);
-
+	entry = ftrace_lookup_ip(hash, func->ip);
 	/*
 	 * Do not allow this rec to match again.
 	 * Yeah, it may waste some memory, but will be removed
-- 
2.20.1