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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 27FF7C43457 for ; Fri, 16 Oct 2020 02:48:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D67802087D for ; Fri, 16 Oct 2020 02:48:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602816508; bh=fnww0eDY2nc5QuOeEIdQygEjQLxesP7fYQ2kuhvFRmc=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=0zjoz0jyCmfWL/D32t0lBzeCTgcXYukmKMbEmbi+cf445cWPw3Kx0wNOrPgVqqryx 3XMm+jZJRLzuwnEUlKka9sNshEwFukeEaCKiI0SsmR4c9ipnKTcxDdlMed50WS6FSh D+vfhdCUNqeZW1ByAd1gW/TDIx5Bb7CHaRuVSSh0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404373AbgJPCs2 (ORCPT ); Thu, 15 Oct 2020 22:48:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:36028 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404351AbgJPCsZ (ORCPT ); Thu, 15 Oct 2020 22:48:25 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9ACFD208C7; Fri, 16 Oct 2020 02:48:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602816504; bh=fnww0eDY2nc5QuOeEIdQygEjQLxesP7fYQ2kuhvFRmc=; h=Date:From:To:Subject:In-Reply-To:From; b=ynccVJ1As/Cw89nSuiJ6ZObz9d3pS2INDye4V5Lfnw+ldyykG+Dg0CHpme4Ogx1zU gWTPOKa4YLBx4+hx8hWBV8eMwUkAqUbLZsfW7693UwDhUxcYBrMDnD1wzs48ST72j1 fS/Nwi9Pp9lYHnk4e62nJCMpBsyscl1XF062NKww= Date: Thu, 15 Oct 2020 19:48:23 -0700 From: Andrew Morton To: akpm@linux-foundation.org, andriy.shevchenko@linux.intel.com, cezary.rojewski@intel.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 116/156] include/linux/list.h: add a macro to test if entry is pointing to the head Message-ID: <20201016024823.Q8Pa4n9fL%akpm@linux-foundation.org> In-Reply-To: <20201015192732.f448da14e9854c7cb7299956@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Andy Shevchenko Subject: include/linux/list.h: add a macro to test if entry is pointing to the head Add a macro to test if entry is pointing to the head of the list which is useful in cases like: list_for_each_entry(pos, &head, member) { if (cond) break; } if (list_entry_is_head(pos, &head, member)) return -ERRNO; that allows to avoid additional variable to be added to track if loop has not been stopped in the middle. While here, convert list_for_each_entry*() family of macros to use a new one. Link: https://lkml.kernel.org/r/20200929134342.51489-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko Reviewed-by: Cezary Rojewski Signed-off-by: Andrew Morton --- include/linux/list.h | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-) --- a/include/linux/list.h~list-add-a-macro-to-test-if-entry-is-pointing-to-the-head +++ a/include/linux/list.h @@ -610,6 +610,15 @@ static inline void list_splice_tail_init pos = n, n = pos->prev) /** + * list_entry_is_head - test if the entry points to the head of the list + * @pos: the type * to cursor + * @head: the head for your list. + * @member: the name of the list_head within the struct. + */ +#define list_entry_is_head(pos, head, member) \ + (&pos->member == (head)) + +/** * list_for_each_entry - iterate over list of given type * @pos: the type * to use as a loop cursor. * @head: the head for your list. @@ -617,7 +626,7 @@ static inline void list_splice_tail_init */ #define list_for_each_entry(pos, head, member) \ for (pos = list_first_entry(head, typeof(*pos), member); \ - &pos->member != (head); \ + !list_entry_is_head(pos, head, member); \ pos = list_next_entry(pos, member)) /** @@ -628,7 +637,7 @@ static inline void list_splice_tail_init */ #define list_for_each_entry_reverse(pos, head, member) \ for (pos = list_last_entry(head, typeof(*pos), member); \ - &pos->member != (head); \ + !list_entry_is_head(pos, head, member); \ pos = list_prev_entry(pos, member)) /** @@ -653,7 +662,7 @@ static inline void list_splice_tail_init */ #define list_for_each_entry_continue(pos, head, member) \ for (pos = list_next_entry(pos, member); \ - &pos->member != (head); \ + !list_entry_is_head(pos, head, member); \ pos = list_next_entry(pos, member)) /** @@ -667,7 +676,7 @@ static inline void list_splice_tail_init */ #define list_for_each_entry_continue_reverse(pos, head, member) \ for (pos = list_prev_entry(pos, member); \ - &pos->member != (head); \ + !list_entry_is_head(pos, head, member); \ pos = list_prev_entry(pos, member)) /** @@ -679,7 +688,7 @@ static inline void list_splice_tail_init * Iterate over list of given type, continuing from current position. */ #define list_for_each_entry_from(pos, head, member) \ - for (; &pos->member != (head); \ + for (; !list_entry_is_head(pos, head, member); \ pos = list_next_entry(pos, member)) /** @@ -692,7 +701,7 @@ static inline void list_splice_tail_init * Iterate backwards over list of given type, continuing from current position. */ #define list_for_each_entry_from_reverse(pos, head, member) \ - for (; &pos->member != (head); \ + for (; !list_entry_is_head(pos, head, member); \ pos = list_prev_entry(pos, member)) /** @@ -705,7 +714,7 @@ static inline void list_splice_tail_init #define list_for_each_entry_safe(pos, n, head, member) \ for (pos = list_first_entry(head, typeof(*pos), member), \ n = list_next_entry(pos, member); \ - &pos->member != (head); \ + !list_entry_is_head(pos, head, member); \ pos = n, n = list_next_entry(n, member)) /** @@ -721,7 +730,7 @@ static inline void list_splice_tail_init #define list_for_each_entry_safe_continue(pos, n, head, member) \ for (pos = list_next_entry(pos, member), \ n = list_next_entry(pos, member); \ - &pos->member != (head); \ + !list_entry_is_head(pos, head, member); \ pos = n, n = list_next_entry(n, member)) /** @@ -736,7 +745,7 @@ static inline void list_splice_tail_init */ #define list_for_each_entry_safe_from(pos, n, head, member) \ for (n = list_next_entry(pos, member); \ - &pos->member != (head); \ + !list_entry_is_head(pos, head, member); \ pos = n, n = list_next_entry(n, member)) /** @@ -752,7 +761,7 @@ static inline void list_splice_tail_init #define list_for_each_entry_safe_reverse(pos, n, head, member) \ for (pos = list_last_entry(head, typeof(*pos), member), \ n = list_prev_entry(pos, member); \ - &pos->member != (head); \ + !list_entry_is_head(pos, head, member); \ pos = n, n = list_prev_entry(n, member)) /** _