From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760426AbXKUNnv (ORCPT ); Wed, 21 Nov 2007 08:43:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759076AbXKUNnl (ORCPT ); Wed, 21 Nov 2007 08:43:41 -0500 Received: from tomts22.bellnexxia.net ([209.226.175.184]:46507 "EHLO tomts22-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759119AbXKUNnk (ORCPT ); Wed, 21 Nov 2007 08:43:40 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Ah4FAO/EQ0dMROHU/2dsb2JhbACBWw Date: Wed, 21 Nov 2007 08:38:21 -0500 From: Mathieu Desnoyers To: Christoph Lameter Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Kay Sievers Subject: Re: Modules: Handle symbols that have a zero value Message-ID: <20071121133821.GA26686@Krystal> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 08:37:09 up 17 days, 18:42, 4 users, load average: 1.09, 1.13, 0.91 User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Christoph Lameter (clameter@sgi.com) wrote: > Another issue that I encountered with the cpu_alloc stuff. > > > > The module subsystem cannot handle symbols that are zero. If symbols are > present that have a zero value then the module resolver prints out > a message that these symbols are unresolved. > > Use ERR_PTR to return an error code instead of 0. This is a bit awkward > since the addresses are handled as unsigned longs. So we need to convert > them everywhere. > > The idea top use ERR_PTR is from Mathieu. > I thought these functions were returning a pointer. Well, since they are simply returning an unsigned long, why not use : return -ENOENT; directly ? (ERR_PTR() in linux/err.h is a simple cast from long to void*). Mathieu > Cc: Mathieu Desnoyers > Cc: Kay Sievers > Signed-off-by: Christoph Lameter > > --- > kernel/module.c | 17 ++++++++++------- > 1 file changed, 10 insertions(+), 7 deletions(-) > > Index: linux-2.6/kernel/module.c > =================================================================== > --- linux-2.6.orig/kernel/module.c 2007-11-20 21:06:29.856965949 -0800 > +++ linux-2.6/kernel/module.c 2007-11-20 21:16:53.001715887 -0800 > @@ -285,7 +285,7 @@ static unsigned long __find_symbol(const > } > } > DEBUGP("Failed to find symbol %s\n", name); > - return 0; > + return (unsigned long)ERR_PTR(-ENOENT); > } > > /* Search for module by name: must hold module_mutex. */ > @@ -648,7 +648,7 @@ void __symbol_put(const char *symbol) > const unsigned long *crc; > > preempt_disable(); > - if (!__find_symbol(symbol, &owner, &crc, 1)) > + if (IS_ERR((void *)__find_symbol(symbol, &owner, &crc, 1))) > BUG(); > module_put(owner); > preempt_enable(); > @@ -792,7 +792,8 @@ static inline int check_modstruct_versio > const unsigned long *crc; > struct module *owner; > > - if (!__find_symbol("struct_module", &owner, &crc, 1)) > + if (IS_ERR((void *)__find_symbol("struct_module", > + &owner, &crc, 1))) > BUG(); > return check_version(sechdrs, versindex, "struct_module", mod, > crc); > @@ -845,7 +846,7 @@ static unsigned long resolve_symbol(Elf_ > /* use_module can fail due to OOM, or module unloading */ > if (!check_version(sechdrs, versindex, name, mod, crc) || > !use_module(mod, owner)) > - ret = 0; > + ret = (unsigned long)ERR_PTR(-EINVAL); > } > return ret; > } > @@ -1238,14 +1239,16 @@ static int verify_export_symbols(struct > const unsigned long *crc; > > for (i = 0; i < mod->num_syms; i++) > - if (__find_symbol(mod->syms[i].name, &owner, &crc, 1)) { > + if (!IS_ERR((void *)__find_symbol(mod->syms[i].name, > + &owner, &crc, 1))) { > name = mod->syms[i].name; > ret = -ENOEXEC; > goto dup; > } > > for (i = 0; i < mod->num_gpl_syms; i++) > - if (__find_symbol(mod->gpl_syms[i].name, &owner, &crc, 1)) { > + if (!IS_ERR((void *)__find_symbol(mod->gpl_syms[i].name, > + &owner, &crc, 1))) { > name = mod->gpl_syms[i].name; > ret = -ENOEXEC; > goto dup; > @@ -1295,7 +1298,7 @@ static int simplify_symbols(Elf_Shdr *se > strtab + sym[i].st_name, mod); > > /* Ok if resolved. */ > - if (sym[i].st_value != 0) > + if (!IS_ERR((void *)sym[i].st_value)) > break; > /* Ok if weak. */ > if (ELF_ST_BIND(sym[i].st_info) == STB_WEAK) -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68