From patchwork Tue Mar 19 02:32:50 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rusty Russell X-Patchwork-Id: 2298611 Return-Path: X-Original-To: patchwork-linux-kbuild@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id 4BEFADFB79 for ; Tue, 19 Mar 2013 04:55:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754622Ab3CSEzt (ORCPT ); Tue, 19 Mar 2013 00:55:49 -0400 Received: from ozlabs.org ([203.10.76.45]:56746 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752399Ab3CSEzt (ORCPT ); Tue, 19 Mar 2013 00:55:49 -0400 Received: by ozlabs.org (Postfix, from userid 1011) id D35CC2C00BE; Tue, 19 Mar 2013 15:55:46 +1100 (EST) From: Rusty Russell To: Andy Lutomirski Cc: linux-kernel@vger.kernel.org, Ben Hutchings , linux-kbuild@vger.kernel.org, "Jon Masters" , "Lucas De Marchi" Subject: Re: [RFC PATCH] Allow optional module parameters In-Reply-To: References: <87ehfhtftn.fsf@rustcorp.com.au> <87sj3tsawh.fsf@rustcorp.com.au> User-Agent: Notmuch/0.14 (http://notmuchmail.org) Emacs/23.4.1 (i686-pc-linux-gnu) Date: Tue, 19 Mar 2013 13:02:50 +1030 Message-ID: <87hak8qfu5.fsf@rustcorp.com.au> MIME-Version: 1.0 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org Andy Lutomirski writes: > On Sun, Mar 17, 2013 at 7:24 PM, Rusty Russell wrote: >> Andy Lutomirski writes: >>> On Thu, Mar 14, 2013 at 10:03 PM, Rusty Russell wrote: >>>> Err, yes. Don't remove module parameters, they're part of the API. Do >>>> you have a particular example? >>> >>> So things like i915.i915_enable_ppgtt, which is there to enable >>> something experimental, needs to stay forever once the relevant >>> feature becomes non-experimental and non-optional? This seems silly. ... >>> Having the module parameter go away while still allowing the module to >>> load seems like a good solution (possibly with a warning in the logs >>> so the user can eventually delete the parameter). >> >> Why not do that for *every* missing parameter then? Why have this weird >> notation where the user must know that the parameter might one day go >> away? > > Fair enough. What about the other approach, then? Always warn if an > option doesn't match (built-in or otherwise) but load the module > anyways. What does everyone think of this? Jon, Lucas, does this match your experience? Thanks, Rusty. Subject: modules: don't fail to load on unknown parameters. Although parameters are supposed to be part of the kernel API, experimental parameters are often removed. In addition, downgrading a kernel might cause previously-working modules to fail to load. On balance, it's probably better to warn, and load the module anyway. Reported-by: Andy Lutomirski Signed-off-by: Rusty Russell --- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/kernel/module.c b/kernel/module.c index 3c2c72d..46db10a 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3206,6 +3206,17 @@ out: return err; } +static int unknown_module_param_cb(char *param, char *val, const char *modname) +{ + /* Check for magic 'dyndbg' arg */ + int ret = ddebug_dyndbg_module_param_cb(param, val, modname); + if (ret != 0) { + printk(KERN_WARNING "%s: unknown parameter '%s' ignored\n", + modname, param); + } + return 0; +} + /* Allocate and load the module: note that size of section 0 is always zero, and we rely on this for optional sections. */ static int load_module(struct load_info *info, const char __user *uargs, @@ -3292,7 +3303,7 @@ static int load_module(struct load_info *info, const char __user *uargs, /* Module is ready to execute: parsing args may do that. */ err = parse_args(mod->name, mod->args, mod->kp, mod->num_kp, - -32768, 32767, &ddebug_dyndbg_module_param_cb); + -32768, 32767, unknown_module_param_cb); if (err < 0) goto bug_cleanup;