From patchwork Fri Nov 26 18:00:38 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dmitry Osipenko X-Patchwork-Id: 12641323 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8EBCC433FE for ; Fri, 26 Nov 2021 18:22:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231892AbhKZSZs (ORCPT ); Fri, 26 Nov 2021 13:25:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57738 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235860AbhKZSXq (ORCPT ); Fri, 26 Nov 2021 13:23:46 -0500 Received: from mail-lf1-x12d.google.com (mail-lf1-x12d.google.com [IPv6:2a00:1450:4864:20::12d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8CF6FC0613E0; Fri, 26 Nov 2021 10:01:55 -0800 (PST) Received: by mail-lf1-x12d.google.com with SMTP id l22so26083122lfg.7; Fri, 26 Nov 2021 10:01:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=6FNFlMpNjS/DNcuPrR0BFjK6OkkBLQhzqGXiB9qxwwI=; b=hZ+VKiheA+ksem4JjsmMOpgKXPoMWgUA+shKPVYf8CWxvU7oWldYH0H+4eQqBAv8FY 4SkaVnaWjJDb3H1aiFaT/XoyReuF35QGFGDgLCvFaztSiusmblr0WrlwXTQg1xtEIIWK Aa+q2fqk9FNKSMyWo+flXzmjZbJfLmFJbzpki04Gyi8vWG/rtl/WU4nTSFM//ACHY153 1B3A/N11y2QrQ67sEfFQXitRorbGN1uZfWp2+IdeAJRQ2AzbU8zozyyZOREyjwZbVOrk byUIk4jH3lFxkf8uNSeTP7J5EN42aV9NcIvUUUtISNly567/tzOwFt6Xc27xO+yi/QYr TYAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=6FNFlMpNjS/DNcuPrR0BFjK6OkkBLQhzqGXiB9qxwwI=; b=CtZ6hgScdccaKzDIHDqE+0Q2vEalPp7UQojpwP+xOMiVQi1Qs8JDPt4Nfte4iSijR2 Q5Tvpn0mhf1xlO0jH8xxrIcz0MasXDD6VXoMEGZav7Uwqw9ZcNyzPpWf4B7sxScZ5QAd 74eTE4qri49I75k9dZEovOS0O+lySIWDeXM+dZJm/uRvdbaffNUWi0sUnGvNSuYbBZDg W45PGA0unfDmEVB5fTfut84X5/I3WXD2z/skya76J1MVlMgPy4dye1FWzfplwbg9NJ41 yuQkL8jW9EBSjBUyb7bqQyJ2/2uGuJbVufPMeK7lMhHeSr0VQDTrg+65vSGoo1XqlOKz Ssiw== X-Gm-Message-State: AOAM530afrBPeUgpnhMR3TP4OYSahRWVXuJ2gx/gOTqz7QFaGSyucyC+ M2ZCDqT4jTfpKneafCXSiZw= X-Google-Smtp-Source: ABdhPJw0q1qKuJneV/VMSHuMj8HXGpja3sBl4tFzSQr3hqui9SbJmQ8r0/YjjnWZYT6ArCZ7g82Plw== X-Received: by 2002:ac2:51b8:: with SMTP id f24mr30853611lfk.83.1637949713891; Fri, 26 Nov 2021 10:01:53 -0800 (PST) Received: from localhost.localdomain (94-29-48-99.dynamic.spd-mgts.ru. [94.29.48.99]) by smtp.gmail.com with ESMTPSA id i32sm553831lfv.295.2021.11.26.10.01.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Nov 2021 10:01:53 -0800 (PST) From: Dmitry Osipenko To: Thierry Reding , Jonathan Hunter , Russell King , Catalin Marinas , Will Deacon , Guo Ren , Geert Uytterhoeven , Greg Ungerer , Joshua Thompson , Thomas Bogendoerfer , Sebastian Reichel , Linus Walleij , Philipp Zabel , Greentime Hu , Vincent Chen , "James E.J. Bottomley" , Helge Deller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Paul Walmsley , Palmer Dabbelt , Albert Ou , Yoshinori Sato , Rich Felker , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Boris Ostrovsky , Juergen Gross , Stefano Stabellini , "Rafael J. Wysocki" , Len Brown , Santosh Shilimkar , Krzysztof Kozlowski , Liam Girdwood , Mark Brown , Pavel Machek , Lee Jones , Andrew Morton , Guenter Roeck , Daniel Lezcano , Andy Shevchenko , Ulf Hansson , alankao@andestech.com, "K . C . Kuen-Chern Lin" Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-csky@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-sh@vger.kernel.org, xen-devel@lists.xenproject.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org Subject: [PATCH v4 02/25] notifier: Add blocking_notifier_call_chain_is_empty() Date: Fri, 26 Nov 2021 21:00:38 +0300 Message-Id: <20211126180101.27818-3-digetx@gmail.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211126180101.27818-1-digetx@gmail.com> References: <20211126180101.27818-1-digetx@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org Add blocking_notifier_call_chain_is_empty() that returns true if call chain is empty. Signed-off-by: Dmitry Osipenko --- include/linux/notifier.h | 2 ++ kernel/notifier.c | 14 ++++++++++++++ 2 files changed, 16 insertions(+) diff --git a/include/linux/notifier.h b/include/linux/notifier.h index 4b80a815b666..924c9d7c8e73 100644 --- a/include/linux/notifier.h +++ b/include/linux/notifier.h @@ -173,6 +173,8 @@ int blocking_notifier_call_chain_robust(struct blocking_notifier_head *nh, int raw_notifier_call_chain_robust(struct raw_notifier_head *nh, unsigned long val_up, unsigned long val_down, void *v); +bool blocking_notifier_call_chain_is_empty(struct blocking_notifier_head *nh); + #define NOTIFY_DONE 0x0000 /* Don't care */ #define NOTIFY_OK 0x0001 /* Suits me */ #define NOTIFY_STOP_MASK 0x8000 /* Don't call further */ diff --git a/kernel/notifier.c b/kernel/notifier.c index b8251dc0bc0f..b20cb7b9b1f0 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -322,6 +322,20 @@ int blocking_notifier_call_chain(struct blocking_notifier_head *nh, } EXPORT_SYMBOL_GPL(blocking_notifier_call_chain); +/** + * blocking_notifier_call_chain_is_empty - Check whether notifier chain is empty + * @nh: Pointer to head of the blocking notifier chain + * + * Checks whether notifier chain is empty. + * + * Returns true is notifier chain is empty, false otherwise. + */ +bool blocking_notifier_call_chain_is_empty(struct blocking_notifier_head *nh) +{ + return !rcu_access_pointer(nh->head); +} +EXPORT_SYMBOL_GPL(blocking_notifier_call_chain_is_empty); + /* * Raw notifier chain routines. There is no protection; * the caller must provide it. Use at your own risk!