From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Triplett Subject: Re: [PATCH] linux/compiler.h: Add __must_hold macro for functions called with a lock held Date: Tue, 9 Oct 2012 13:36:28 -0700 Message-ID: <20121009203628.GB3616@jtriplet-mobl1> References: <20121008020610.GA9197@leaf> <20121009130637.5e61078f.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from relay4-d.mail.gandi.net ([217.70.183.196]:53525 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752962Ab2JIUgg (ORCPT ); Tue, 9 Oct 2012 16:36:36 -0400 Content-Disposition: inline In-Reply-To: <20121009130637.5e61078f.akpm@linux-foundation.org> Sender: linux-sparse-owner@vger.kernel.org List-Id: linux-sparse@vger.kernel.org To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-sparse@vger.kernel.org, Ed Cashin , Christopher Li , Andi Kleen On Tue, Oct 09, 2012 at 01:06:37PM -0700, Andrew Morton wrote: > On Sun, 7 Oct 2012 19:06:10 -0700 > Josh Triplett wrote: > > > linux/compiler.h has macros to denote functions that acquire or release > > locks, but not to denote functions called with a lock held that return > > with the lock still held. Add a __must_hold macro to cover that case. > > hum. How does this work? Any code examples and sample sparse output? > Does it apply to all lock types, etc? It applies to all the same lock types that __acquires and __releases apply to: currently everything since Sparse doesn't actually do anything with the parameter, just the context value. Various code examples already exist in the kernel tree for __acquires and __releases, and the mailing list contains many reports of the Sparse context warnings. Just as __acquires and __release annotate functions that return with a lock acquired and get called with a lock that they drop (respectively), __must_hold annotates a function called with a lock acquired that return with that lock still acquired. > IOW, where is all this stuff documented? The Sparse manpage documents the context bits reasonably well. Other than that, nowhere that I know of other than the Sparse testsuite and the source trees of projects like Linux that use Sparse. - Josh Triplett