From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753824AbbAVBFK (ORCPT ); Wed, 21 Jan 2015 20:05:10 -0500 Received: from ozlabs.org ([103.22.144.67]:59789 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753270AbbAVBFA convert rfc822-to-8bit (ORCPT ); Wed, 21 Jan 2015 20:05:00 -0500 From: Rusty Russell To: Andrey Tsyvarev Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar Subject: Re: [PATCH] kernel/module.c: Free lock-classes if parse_args failed In-Reply-To: <54BF8439.2000905@ispras.ru> References: <1421216708-1975-1-git-send-email-tsyvarev@ispras.ru> <87iog2arfk.fsf@rustcorp.com.au> <54BE082A.20207@ispras.ru> <87d268c3mi.fsf@rustcorp.com.au> <54BF8439.2000905@ispras.ru> User-Agent: Notmuch/0.17 (http://notmuchmail.org) Emacs/24.3.1 (x86_64-pc-linux-gnu) Date: Thu, 22 Jan 2015 11:10:30 +1030 Message-ID: <87bnlrwsu9.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrey Tsyvarev writes: > 21.01.2015 4:40, Rusty Russell пишет: >> Andrey Tsyvarev writes: >>> 20.01.2015 9:37, Rusty Russell пишет: >>>> Andrey Tsyvarev writes: >>>>> parse_args call module parameters' .set handlers, which may use locks defined in the module. >>>>> So, these classes should be freed in case parse_args returns error(e.g. due to incorrect parameter passed). >>>> Thanks, this seems right. Applied. >>>> >>>> But this makes me ask: where is lockdep_free_key_range() called on the >>>> module init code? It doesn't seem to be at all... >>> As I understand, locks are not allowed to be defined in the module init >>> section. So, no needs to call lockdep_free_key_range() for it. >>> This has a sense: objects from that section are allowed to be used only >>> by module->init() function. But a single function call doesn't require >>> any synchronization wrt itself. >> I don't know that we have any __initdata locks; it would be really >> weird. >> >> But change 'static DEFINE_MUTEX(mutex_param);' to 'static __initdata >> DEFINE_MUTEX(mutex_param);' to test. > Compiler warns about sections mismatch, but the test works. > > According to lockdep_free_key_range() code, lock class is cleared not > only according to > its key(which is equal to lock address in the case of static lock) but > also according to its name. What happens if you later register another lock at that address, since the memory is freed? A quick grep revealed no __initdata locks in the kernel, so I don't think we care anyway. Cheers, Rusty.