linux-kernel - Re: [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu

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: <50B8542C.3010109@gmail.com>
Date:	Fri, 30 Nov 2012 14:37:32 +0800
From:	Shan Wei <shanwei88@...il.com>
To:	rostedt@...dmis.org, fweisbec@...il.com, mingo@...hat.com,
	Kernel-Maillist <linux-kernel@...r.kernel.org>,
	Christoph Lameter <cl@...ux.com>
Subject: Re: [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu_var

ping ......


Shan Wei said, at 2012/11/19 13:21:
> From: Shan Wei <davidshan@...cent.com>
> 
> __this_cpu_inc_return() or __this_cpu_dec generates a single instruction,
> which is faster than __get_cpu_var operation.
> 
> Signed-off-by: Shan Wei <davidshan@...cent.com>
> ---
>  kernel/trace/trace.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 18c0aa8..3795694 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -1313,7 +1313,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
>  	 */
>  	preempt_disable_notrace();
>  
> -	use_stack = ++__get_cpu_var(ftrace_stack_reserve);
> +	use_stack = __this_cpu_inc_return(ftrace_stack_reserve);
>  	/*
>  	 * We don't need any atomic variables, just a barrier.
>  	 * If an interrupt comes in, we don't care, because it would
> @@ -1367,7 +1367,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
>   out:
>  	/* Again, don't let gcc optimize things here */
>  	barrier();
> -	__get_cpu_var(ftrace_stack_reserve)--;
> +	__this_cpu_dec(ftrace_stack_reserve);
>  	preempt_enable_notrace();
>  
>  }
> 

--
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/