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[94.29.46.111]) by smtp.gmail.com with ESMTPSA id y4sm1197172ljp.16.2021.12.12.13.03.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 12 Dec 2021 13:03:36 -0800 (PST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: f956a778-5b8e-11ec-bf02-3911bdbc85ab 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=n3cwwyKh/hwErnoFuV8i3YcIMR9FHZoMKEZSbOKAmdY=; b=Ex8lL4mdgUiRHYGoAXofDELzYU2M39Rf62MPEL6+NwhL4DG7f7g8blGnth50zzv9nv XtgwZ9AQGnJnLqVio+QWKRb0Z2UFZU13/SlOZ6knhCS8nzv79jUJrhvhvCtb6xbOGhRe QCo64//4R6yL9xhgOYc3zcYTNZnDzQezIWCwpso0yHMq6Gqm01cbjFNzL9wdR1IpObJX QNX5u0vTw2iIw9GwynLoMaZBVQkfGVwbmM4effBPRqVI72+jfv9/MdqbIDB9jPZ8pJzw hYqD/Yu8obJVLM9NSCzZb3jXy2mxfU4mU/jDrUalTCSK4fBVmU6wUB9oiNX1E5nzJKlr /TtA== 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=n3cwwyKh/hwErnoFuV8i3YcIMR9FHZoMKEZSbOKAmdY=; b=PzzL4a+a8RVWwOQjJQQpG+yCe0Gl6BNKbRHf+/bF4fKGbyYI+aDo8CkgkEKPBhqIWX EMTp75Z/bJYAJb47ga6/rpMasbjU3P9/JALLs0jBmQL77ECGsAAUeRMpPUUBMwlL9gpG Y0ShUkJrbZgpg50kai3yJJ65/C1Lau6CFCoBlngyJzBkTnycjrl/KVcqC5lkTZBjWKuY CnFFyFjQAzdvdeBn63NGyx55la99MPBTcWvyTcaxe+fT8aKpF3WaDF5zgdCVf1IT5hru AERyZ2FOIMk8lipbJHYbgO14nZ/MJAleRpCCP+zNHmOSud5zxxWOcNRsFmBiwCjEQdDT AFrQ== X-Gm-Message-State: AOAM532yjwT0M7NK2tGEShLS28V3omtlUYawjCcsfaOo22dayBJUQG7m 88RHuQOzBAsJ9+NEkMzSKS8= X-Google-Smtp-Source: ABdhPJyVUXR8xADdHsxaMm4O/Lfphg0rT3u//x42eqt+aVA8OPTC8ytA0fee16pgBcrKP9uKJF2ykQ== X-Received: by 2002:a05:651c:514:: with SMTP id o20mr26693103ljp.393.1639343016405; Sun, 12 Dec 2021 13:03:36 -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" , =?utf-8?b?TWljaGHFgiBNaXJv?= =?utf-8?b?c8WCYXc=?= Cc: 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 v5 01/21] notifier: Add blocking_notifier_call_chain_is_empty() Date: Mon, 13 Dec 2021 00:02:49 +0300 Message-Id: <20211212210309.9851-2-digetx@gmail.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211212210309.9851-1-digetx@gmail.com> References: <20211212210309.9851-1-digetx@gmail.com> MIME-Version: 1.0 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 | 13 +++++++++++++ 2 files changed, 15 insertions(+) diff --git a/include/linux/notifier.h b/include/linux/notifier.h index 87069b8459af..d4717bc0ab85 100644 --- a/include/linux/notifier.h +++ b/include/linux/notifier.h @@ -173,6 +173,8 @@ extern int blocking_notifier_call_chain_robust(struct blocking_notifier_head *nh extern int raw_notifier_call_chain_robust(struct raw_notifier_head *nh, unsigned long val_up, unsigned long val_down, void *v); +extern 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..e30d24ee88e9 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -322,6 +322,19 @@ 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); +} + /* * Raw notifier chain routines. There is no protection; * the caller must provide it. Use at your own risk!