From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ed Cashin Subject: Re: "unexpected unlock" when unlocking, conditional, lock in loop Date: Sun, 7 Oct 2012 16:28:16 -0500 Message-ID: References: <1349552876.20963@cat.he.net> <20121006202102.GA28179@leaf> <66AC2AD6-C0FA-4F60-850A-D8C9426184B8@coraid.com> <20121007023946.GA30713@leaf> <20121007194552.GA909@leaf> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Return-path: Received: from server505f.appriver.com ([98.129.35.10]:2777 "EHLO server505.appriver.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751278Ab2JGV2V convert rfc822-to-8bit (ORCPT ); Sun, 7 Oct 2012 17:28:21 -0400 In-Reply-To: <20121007194552.GA909@leaf> Content-Language: en-US Sender: linux-sparse-owner@vger.kernel.org List-Id: linux-sparse@vger.kernel.org To: Josh Triplett Cc: "linux-sparse@vger.kernel.org" On Oct 7, 2012, at 3:45 PM, Josh Triplett wrote: > On Sun, Oct 07, 2012 at 07:49:25AM -0500, Ed Cashin wrote: ... >> CC [M] drivers/block/aoe/demo.o >> drivers/block/aoe/demo.c:9: warning: `context' attribute directive ignored >> drivers/block/aoe/demo.c:9: error: expected `,' or `;' before `{' token >> make[1]: *** [drivers/block/aoe/demo.o] Error 1 >> make: *** [drivers/block/aoe/aoe.ko] Error 2 > > Oh, that complaint doesn't come from Sparse; that comes from GCC, since > GCC doesn't understand the context attribute. Look at > include/linux/compiler.h; it has wrapper macros for the various Sparse > attributes, and defines them to nothing when not compiling with Sparse. > If you want to use the context attribute to denote a lock held through a > function, you need a patch like this: > > From 0b862fc1a131a874d157420e9443f16a714596ef Mon Sep 17 00:00:00 2001 > From: Josh Triplett > Date: Sun, 7 Oct 2012 12:41:13 -0700 > Subject: [PATCH] linux/compiler.h: Add __must_hold macro for functions called with a lock held Ah. OK. So... would you like me to submit your patch to the LKML, or are you doing that? It seems like a needed addition. > 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 this case. > > Signed-off-by: Josh Triplett > --- > include/linux/compiler.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > index f430e41..b121554 100644 > --- a/include/linux/compiler.h > +++ b/include/linux/compiler.h > @@ -10,6 +10,7 @@ > # define __force __attribute__((force)) > # define __nocast __attribute__((nocast)) > # define __iomem __attribute__((noderef, address_space(2))) > +# define __must_hold(x) __attribute__((context(x,1,1))) > # define __acquires(x) __attribute__((context(x,0,1))) > # define __releases(x) __attribute__((context(x,1,0))) > # define __acquire(x) __context__(x,1) > @@ -33,6 +34,7 @@ extern void __chk_io_ptr(const volatile void __iomem *); > # define __chk_user_ptr(x) (void)0 > # define __chk_io_ptr(x) (void)0 > # define __builtin_warning(x, y...) (1) > +# define __must_hold(x) > # define __acquires(x) > # define __releases(x) > # define __acquire(x) (void)0 -- Ed Cashin ecashin@coraid.com