From: Avi Kivity <avi@redhat.com>
To: Jason Baron <jbaron@redhat.com>
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu,
mathieu.desnoyers@polymtl.ca, hpa@zytor.com, tglx@linutronix.de,
rostedt@goodmis.org, andi@firstfloor.org, roland@redhat.com,
rth@redhat.com, mhiramat@redhat.com, fweisbec@gmail.com
Subject: Re: [PATCH 2/5] jump label: base patch
Date: Mon, 22 Mar 2010 23:01:39 +0200 [thread overview]
Message-ID: <4BA7DAB3.5030002@redhat.com> (raw)
In-Reply-To: <79304b525d61cb0e7516cdee1ddcdb5ac3f2579a.1269272444.git.jbaron@redhat.com>
On 03/22/2010 06:07 PM, Jason Baron wrote:
> base patch to implement 'jump labeling'. Based on a new 'asm goto' inline
> assembly gcc mechanism, we can now branch to labels from an 'asm goto'
> statment. This allows us to create a 'no-op' fastpath, which can subsequently
> be patched with a jump to the slowpath code. This is useful for code which
> might be rarely used, but which we'd like to be able to call, if needed.
> Tracepoints are the current usecase that these are being implemented for.
>
>
> +
> +#define JUMP_LABEL(tag, label, cond) \
> + if (unlikely(cond)) \
> + goto label;
>
Suggest wrapping with do { } while (0) to avoid problems with the
dangling semicolon or a trailing 'else' from an outer if ().
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
next prev parent reply other threads:[~2010-03-22 21:02 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-22 16:07 [PATCH 0/5] jump label v5 Jason Baron
2010-03-22 16:07 ` [PATCH 1/5] jump label: notifier atomic call chain notrace Jason Baron
2010-03-22 17:55 ` Masami Hiramatsu
2010-03-22 16:07 ` [PATCH 2/5] jump label: base patch Jason Baron
2010-03-22 20:04 ` Steven Rostedt
2010-03-22 21:01 ` Avi Kivity [this message]
2010-03-26 21:30 ` Masami Hiramatsu
2010-03-22 16:07 ` [PATCH 3/5] jump label: x86 support Jason Baron
2010-03-22 16:40 ` Steven Rostedt
2010-03-22 20:40 ` Jason Baron
2010-03-22 16:07 ` [PATCH 4/5] jump label: tracepoint support Jason Baron
2010-03-22 16:43 ` Steven Rostedt
2010-03-22 20:44 ` Jason Baron
2010-03-22 16:07 ` [PATCH 5/5] jump label: add module support Jason Baron
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