From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755649AbbLDIqX (ORCPT ); Fri, 4 Dec 2015 03:46:23 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:55732 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755594AbbLDIqU (ORCPT ); Fri, 4 Dec 2015 03:46:20 -0500 Date: Fri, 4 Dec 2015 00:46:13 -0800 From: Andrew Morton To: Rasmus Villemoes Cc: Kees Cook , Al Viro , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 14/14] lib/test_printf.c: test dentry printing Message-Id: <20151204004613.8bb1e7b9.akpm@linux-foundation.org> In-Reply-To: <87y4da633x.fsf@rasmusvillemoes.dk> References: <1449175873-1780-1-git-send-email-linux@rasmusvillemoes.dk> <1449175873-1780-15-git-send-email-linux@rasmusvillemoes.dk> <20151203161910.c33ab41d21e0d3bfc6fdb060@linux-foundation.org> <87y4da633x.fsf@rasmusvillemoes.dk> X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.9; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 04 Dec 2015 09:16:02 +0100 Rasmus Villemoes wrote: > On Fri, Dec 04 2015, Andrew Morton wrote: > > > On Thu, 3 Dec 2015 21:51:13 +0100 Rasmus Villemoes wrote: > > > >> +static struct dentry test_dentry[4] __initdata = { > >> + { .d_parent = &test_dentry[0], > >> + .d_name = { .len = 3, .name = test_dentry[0].d_iname }, > >> + .d_iname = "foo" }, > > > > Confused. qstr has no .len. > > > > lib/test_printf.c:332: error: unknown field 'len' specified in initializer > > Huh? It goes without saying that I've compiled and run this, and never > seen this problem. struct qstr does have a len member, though it's > hidden inside an anonymous struct inside an anonymous union. But at > least my gcc (4.9) has no problem with those initializers - and > fs/dcache.c happily accesses name->len all the time (how else would one > get at the member). Also note the lack of 0day complaints. What tool > gave that error? > Ah, OK, that's the gcc-4.4.4 bug with initialization of anonymous unions. I really should get a new compiler, but running old compilers has value - it finds problems with old compilers! I've never found a workaround for this problem so the fix thus far has been to do the initialization in regular old C code. However it appears that the QSTR_INIT() macro (which you should have used anyway!) contains some magic sauce. This fixes it: --- a/lib/test_printf.c~lib-test_printfc-test-dentry-printing-fix +++ a/lib/test_printf.c @@ -329,16 +329,16 @@ uuid(void) static struct dentry test_dentry[4] __initdata = { { .d_parent = &test_dentry[0], - .d_name = { .len = 3, .name = test_dentry[0].d_iname }, + .d_name = QSTR_INIT(test_dentry[0].d_iname, 3), .d_iname = "foo" }, { .d_parent = &test_dentry[0], - .d_name = { .len = 5, .name = test_dentry[1].d_iname }, + .d_name = QSTR_INIT(test_dentry[1].d_iname, 5), .d_iname = "bravo" }, { .d_parent = &test_dentry[1], - .d_name = { .len = 4, .name = test_dentry[2].d_iname }, + .d_name = QSTR_INIT(test_dentry[2].d_iname, 4), .d_iname = "alfa" }, { .d_parent = &test_dentry[2], - .d_name = { .len = 5, .name = test_dentry[3].d_iname }, + .d_name = QSTR_INIT(test_dentry[3].d_iname, 5), .d_iname = "romeo" }, }; I assume the code still works ;) And while I'm there... From: Andrew Morton Subject: include/linux/dcache.h: remove semicolons from HASH_LEN_DECLARE A little cleanup - the invocation site provdes the semicolon. Cc: Rasmus Villemoes Cc: Al Viro Signed-off-by: Andrew Morton --- include/linux/dcache.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN include/linux/dcache.h~include-linux-dcacheh-remove-semicolons-from-hash_len_declare include/linux/dcache.h --- a/include/linux/dcache.h~include-linux-dcacheh-remove-semicolons-from-hash_len_declare +++ a/include/linux/dcache.h @@ -27,10 +27,10 @@ struct vfsmount; /* The hash is always the low bits of hash_len */ #ifdef __LITTLE_ENDIAN - #define HASH_LEN_DECLARE u32 hash; u32 len; + #define HASH_LEN_DECLARE u32 hash; u32 len #define bytemask_from_count(cnt) (~(~0ul << (cnt)*8)) #else - #define HASH_LEN_DECLARE u32 len; u32 hash; + #define HASH_LEN_DECLARE u32 len; u32 hash #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8)) #endif _