From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752833AbaEVCJ6 (ORCPT ); Wed, 21 May 2014 22:09:58 -0400 Received: from mail-pa0-f45.google.com ([209.85.220.45]:57938 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751218AbaEVCJ4 (ORCPT ); Wed, 21 May 2014 22:09:56 -0400 From: Grant Likely Subject: Re: [PATCH 2/3] of: Make of_find_node_by_path() handle /aliases To: frowand.list@gmail.com Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, David Daney , Pantelis Antoniou In-Reply-To: <537C1252.3090900@gmail.com> References: <1399993115-21552-1-git-send-email-grant.likely@linaro.org> <1399993115-21552-3-git-send-email-grant.likely@linaro.org> <53757D25.1060005@gmail.com> <20140516105444.C1DB7C42277@trevor.secretlab.ca> <20140518092730.109AAC40B8A@trevor.secretlab.ca> <537C1252.3090900@gmail.com> Date: Thu, 22 May 2014 10:16:00 +0900 Message-Id: <20140522011600.C0014C40B13@trevor.secretlab.ca> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 20 May 2014 19:41:22 -0700, Frank Rowand wrote: > On 5/18/2014 2:27 AM, Grant Likely wrote: > > On Fri, 16 May 2014 11:54:44 +0100, Grant Likely wrote: > >> On Thu, 15 May 2014 19:51:17 -0700, Frank Rowand wrote: > >>> On 5/13/2014 7:58 AM, Grant Likely wrote: > >>>> Make of_find_node_by_path() handle aliases as prefixes. To make this > >>>> work the name search is refactored to search by path component instead > >>>> of by full string. This should be a more efficient search, and it makes > >>>> it possible to start a search at a subnode of a tree. > >>>> > >>>> Signed-off-by: David Daney > >>>> Signed-off-by: Pantelis Antoniou > >>>> [grant.likely: Rework to not require allocating at runtime] > >>>> Acked-by: Rob Herring > >>>> Signed-off-by: Grant Likely > >>>> --- > >>>> drivers/of/base.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++---- > >>>> 1 file changed, 56 insertions(+), 4 deletions(-) > >>>> > >>>> diff --git a/drivers/of/base.c b/drivers/of/base.c > >>>> index 6e240698353b..60089b9a3014 100644 > >>>> --- a/drivers/of/base.c > >>>> +++ b/drivers/of/base.c > >>>> @@ -771,9 +771,38 @@ struct device_node *of_get_child_by_name(const struct device_node *node, > >>>> } > >>>> EXPORT_SYMBOL(of_get_child_by_name); > >>>> > >>>> +static struct device_node *__of_find_node_by_path(struct device_node *parent, > >>>> + const char *path) > >>>> +{ > >>>> + struct device_node *child; > >>>> + int len = strchrnul(path, '/') - path; > >>>> + > >>>> + if (!len) > >>>> + return parent; > >>> > >>> (!len) is true if the the final character of the path passed into of_find_node_by_path() > >>> was "/". Strictly speaking, ->full_name will never end with "/", so the return value > >>> should be NULL, indicating that the match fails. > >> > >> Ah, good catch. I should add a test case for that. > > > > In my testing this looks okay. The while loop that calls into > > __of_find_node_by_path() looks like this: > > > > while (np && *path == '/') { > > path++; /* Increment past '/' delimiter */ > > np = __of_find_node_by_path(np, path); > > path = strchrnul(path, '/'); > > } > > > > If the path ends with a '/', then the loop will go around one more time. > > The pointer will be incremented to point at the null character and len > > will be null because strchrnul() will point at the last item. > > Yes, that was my point. The old version of of_find_node_by_path() would not > find a match if the path ended with a "/" (unless the full path was "/"). > This patch series changes the behavior to be a match. > > I will reply to this email with an additional patch that restores the > original behavior. > > If you move the additional test cases you provide below and the test cases > in patch 3 to the beginning of the series, you can see the before and after > behavior of adding patch 1 and patch 2. Ah, I see. That raises the question about what the behaviour /should/ be. Off the top of my head, matching against a trailing '/' seems to be okay. Are there situations that you see or can think of where matching would be the wrong thing to do? g.