From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andreea-Cristina Bernat <bernat.ada@gmail.com>
Subject: [PATCH 09/11] kernel: trace_syscalls: Replace rcu_assign_pointer() with RCU_INIT_POINTER()
Date: Mon, 06 Oct 2014 17:35:53 -0400 [thread overview]
Message-ID: <20141006213631.498529423@goodmis.org> (raw)
In-Reply-To: <20141006213544.344821619@goodmis.org>
[-- Attachment #1: 0009-kernel-trace_syscalls-Replace-rcu_assign_pointer-wit.patch --]
[-- Type: text/plain, Size: 1701 bytes --]
From: Andreea-Cristina Bernat <bernat.ada@gmail.com>
The uses of "rcu_assign_pointer()" are NULLing out the pointers.
According to RCU_INIT_POINTER()'s block comment:
"1. This use of RCU_INIT_POINTER() is NULLing out the pointer"
it is better to use it instead of rcu_assign_pointer() because it has a
smaller overhead.
The following Coccinelle semantic patch was used:
@@
@@
- rcu_assign_pointer
+ RCU_INIT_POINTER
(..., NULL)
Link: http://lkml.kernel.org/p/20140822142822.GA32391@ada
Signed-off-by: Andreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_syscalls.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 759d5e004517..4dc8b79c5f75 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -425,7 +425,7 @@ static void unreg_event_syscall_enter(struct ftrace_event_file *file,
return;
mutex_lock(&syscall_trace_lock);
tr->sys_refcount_enter--;
- rcu_assign_pointer(tr->enter_syscall_files[num], NULL);
+ RCU_INIT_POINTER(tr->enter_syscall_files[num], NULL);
if (!tr->sys_refcount_enter)
unregister_trace_sys_enter(ftrace_syscall_enter, tr);
mutex_unlock(&syscall_trace_lock);
@@ -463,7 +463,7 @@ static void unreg_event_syscall_exit(struct ftrace_event_file *file,
return;
mutex_lock(&syscall_trace_lock);
tr->sys_refcount_exit--;
- rcu_assign_pointer(tr->exit_syscall_files[num], NULL);
+ RCU_INIT_POINTER(tr->exit_syscall_files[num], NULL);
if (!tr->sys_refcount_exit)
unregister_trace_sys_exit(ftrace_syscall_exit, tr);
mutex_unlock(&syscall_trace_lock);
--
2.0.1
next prev parent reply other threads:[~2014-10-06 21:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-06 21:35 [PATCH 00/11] [GIT PULL] tracing: Updates for 3.18 Steven Rostedt
2014-10-06 21:35 ` [PATCH 01/11] ftrace: Add separate function for non recursive callbacks Steven Rostedt
2014-10-06 21:35 ` [PATCH 02/11] ftrace: Add helper function ftrace_ops_get_func() Steven Rostedt
2014-10-06 21:35 ` [PATCH 03/11] ftrace: Set callback to ftrace_stub when no ops are registered Steven Rostedt
2014-10-06 21:35 ` [PATCH 04/11] ftrace: Remove freeing of old_hash from ftrace_hash_move() Steven Rostedt
2014-10-06 21:35 ` [PATCH 05/11] ftrace: Grab any ops for a rec for enabled_functions output Steven Rostedt
2014-10-06 21:35 ` [PATCH 06/11] ftrace: Annotate the ops operation on update Steven Rostedt
2014-10-06 21:35 ` [PATCH 07/11] ftrace: Replace tramp_hash with old_*_hash to save space Steven Rostedt
2014-10-06 21:35 ` [PATCH 08/11] tracing: generate RCU warnings even when tracepoints are disabled Steven Rostedt
2014-10-07 2:39 ` Paul E. McKenney
2014-10-06 21:35 ` Steven Rostedt [this message]
2014-10-06 21:35 ` [PATCH 10/11] ftrace: Add sanity check when unregistering last ftrace_ops Steven Rostedt
2014-10-06 21:35 ` [PATCH 11/11] ftrace: Only disable ftrace_enabled to test buffer in selftest Steven Rostedt
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