From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DAEA1C282CE for ; Tue, 9 Apr 2019 15:21:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3E752084F for ; Tue, 9 Apr 2019 15:21:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726529AbfDIPVh (ORCPT ); Tue, 9 Apr 2019 11:21:37 -0400 Received: from mga05.intel.com ([192.55.52.43]:40140 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726431AbfDIPVg (ORCPT ); Tue, 9 Apr 2019 11:21:36 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Apr 2019 08:21:35 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,329,1549958400"; d="scan'208";a="335205951" Received: from smile.fi.intel.com (HELO smile) ([10.237.72.86]) by fmsmga006.fm.intel.com with ESMTP; 09 Apr 2019 08:21:31 -0700 Received: from andy by smile with local (Exim 4.92) (envelope-from ) id 1hDsZ0-0004gu-6p; Tue, 09 Apr 2019 18:21:30 +0300 Date: Tue, 9 Apr 2019 18:21:30 +0300 From: Andriy Shevchenko To: "Paul E. McKenney" Cc: Christoph Hellwig , Jacob Pan , iommu@lists.linux-foundation.org, LKML , Joerg Roedel , David Woodhouse , Alex Williamson , Jean-Philippe Brucker , Yi Liu , "Tian, Kevin" , Raj Ashok , Lu Baolu Subject: Re: [PATCH 01/18] drivers core: Add I/O ASID allocator Message-ID: <20190409152130.GS9224@smile.fi.intel.com> References: <1554767973-30125-1-git-send-email-jacob.jun.pan@linux.intel.com> <1554767973-30125-2-git-send-email-jacob.jun.pan@linux.intel.com> <20190409100049.GC9224@smile.fi.intel.com> <20190409100436.GA28683@infradead.org> <20190409103030.GK9224@smile.fi.intel.com> <20190409145308.GZ14111@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190409145308.GZ14111@linux.ibm.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 09, 2019 at 07:53:08AM -0700, Paul E. McKenney wrote: > On Tue, Apr 09, 2019 at 01:30:30PM +0300, Andriy Shevchenko wrote: > > On Tue, Apr 09, 2019 at 03:04:36AM -0700, Christoph Hellwig wrote: > > > On Tue, Apr 09, 2019 at 01:00:49PM +0300, Andriy Shevchenko wrote: > > > > I think it makes sense to add a helper macro to rcupdate.h > > > > (and we have several cases in kernel that can utilize it) > > > > > > > > #define kfree_non_null_rcu(ptr, rcu_head) \ > > > > do { \ > > > > if (ptr) \ > > > > kfree_rcu(ptr, rcu_head); \ > > > > } while (0) > > > > > > > > as a more common pattern for resource deallocators. > > > > > > I think that should move straight into kfree_rcu. > > > > Possible. I didn't dare to offer this due to lack of knowledge how it's used in > > other places. > > > > > In general > > > we expect *free* to deal with NULL pointers transparently, so we > > > should do so here as well. > > > > Exactly my point, thanks. > > As shown below? Looks pretty much good to me, thanks! Reviewed-by: Andriy Shevchenko > > And now that you mention it, it is a bit surprising that no one has > complained before. ;-) > > Thanx, Paul > > ------------------------------------------------------------------------ > > commit 23ad938244968e9d2a8001a1c52887c113b182f6 > Author: Paul E. McKenney > Date: Tue Apr 9 07:48:18 2019 -0700 > > rcu: Make kfree_rcu() ignore NULL pointers > > This commit makes the kfree_rcu() macro's semantics be consistent > with the likes of kfree() by adding a check for NULL pointers, so > that kfree_rcu(NULL, ...) is a no-op. > > Reported-by: Andriy Shevchenko > Reported-by: Christoph Hellwig > Signed-off-by: Paul E. McKenney > > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > index 922bb6848813..c68649b9bcec 100644 > --- a/include/linux/rcupdate.h > +++ b/include/linux/rcupdate.h > @@ -828,9 +828,13 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) > * The BUILD_BUG_ON check must not involve any function calls, hence the > * checks are done in macros here. > */ > -#define kfree_rcu(ptr, rcu_head) \ > - __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) > - > +#define kfree_rcu(ptr, rhf) \ > +do { \ > + typeof (ptr) ___p = (ptr); \ > + \ > + if (___p) \ > + __kfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \ > +} while (0) > > /* > * Place this after a lock-acquisition primitive to guarantee that > -- With Best Regards, Andy Shevchenko