linux-kernel - [RFC PATCH 05/10] ftrace: Drop buffer check in function profiler callbacks

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1264122982-1553-6-git-send-regression-fweisbec@gmail.com>
Date:	Fri, 22 Jan 2010 02:16:17 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Li Zefan <lizf@...fujitsu.com>,
	Lai Jiangshan <laijs@...fujitsu.com>
Subject: [RFC PATCH 05/10] ftrace: Drop buffer check in function profiler callbacks

Drop the null check on hlist->hash. It is wasteful because
we don't register the tracer if the buffer allocation failed,
and the memory barrier in register_ftrace_graph() ensure it
is visible to the callbacks right away.

Also we know the tracing callbacks won't be called after
register_ftrace_graph(), so subsequent buffer resets are safe
too.

Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Li Zefan <lizf@...fujitsu.com>
Cc: Lai Jiangshan <laijs@...fujitsu.com>
---
 kernel/trace/ftrace.c |    5 -----
 1 files changed, 0 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3cdb35e..dfd8f7c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -384,8 +384,6 @@ function_profile_call(unsigned long ip, unsigned long parent_ip)
 	local_irq_save(flags);
 
 	hlist = &__get_cpu_var(func_hlist_cpu);
-	if (!hlist->hash)
-		goto out;
 
 	rec = function_find_hlist_node(hlist, ip);
 	if (!rec) {
@@ -415,8 +413,6 @@ static void profile_graph_return(struct ftrace_graph_ret *trace)
 
 	local_irq_save(flags);
 	hlist = &__get_cpu_var(func_hlist_cpu);
-	if (!hlist->hash)
-		goto out;
 
 	calltime = trace->rettime - trace->calltime;
 
@@ -439,7 +435,6 @@ static void profile_graph_return(struct ftrace_graph_ret *trace)
 	if (rec)
 		rec->time += calltime;
 
- out:
 	local_irq_restore(flags);
 }
 
-- 
1.6.2.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/