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[79.139.188.96]) by smtp.gmail.com with ESMTPSA id p17sm1625266lfu.209.2021.11.07.16.47.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 07 Nov 2021 16:47:50 -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: 8038b8c2-402d-11ec-a9d2-d9f7a1cc8784 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=ap3A83fg5fKkLgYcPLGj4ujgDQbjKUnCHl1tJwJk0YYfyEiGzkqPECTzKOM1YfoD1L 7Tv1IQL0qy27hRaO+2V8mMNwuPhmt0RnGYTpIVZHvmMlW0N/ak+ket1f1gl2JZ7gk9d3 fAQNCztH/PN7x2xYeGLPMEE2nD1cIjm0qVz550BDVg6mI6jct3ZSJyVKmro1IFNn1yWr IPyHSXGPZHiix8heM9Rffd6oJdFFpg7+1b1krhUZivdkkY35o0on0Qdc3YJ5KDtW0+lB QH16yrcERPBYXXBZaoG/Grh/x98enYzxE1lM3ST5QIPReMfvmXUk1iBZ/CuGE0IZaTFO vjnA== 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=ejHSHVrU6P8WgyKTCFo/VRa3FUHkcmjGWfH0uagaRJS//xh0LYB4QvQu9iipbGJzJP 1CCrAmfpv0U9o6RKn+pLmndtpyvO90TeBMHdFRzBpfcNNM4P5jYgdtxHBEa/DHlRbA6w DC7UrP4qEGehdLJinCtSnrTay47tAu/V3A8Z2/rkNPv37UJOw4n+7G/Cuyqj1Tg2rPlu OE53XNxLa7oICI09j4yKXNhWQOw0th0P2DDk3TuYRiHM5Si9VSXRiCIUg/WVEjKAtF+f UecTbhbIFs1B9Oj/qzg4j7YhZiiLk5rxQEddygxYo1dyweSAUq36t2aXuOqZyRPl+8n5 aC8Q== X-Gm-Message-State: AOAM530/S10WRIBiUp9lr6GO1vf3q1qD9rgY0Ab1NIZybl7ozJ0109gP zYGfe6svvCPo4d+SMCGNTUo= X-Google-Smtp-Source: ABdhPJyrOsT2LfeoRDePz9gvXDRZ9T+n52FCNueqjAZN/qgGSzpYZGgdBodfU1+UMWgFhWWsCOX6NQ== X-Received: by 2002:a2e:8799:: with SMTP id n25mr26944321lji.377.1636332470861; Sun, 07 Nov 2021 16:47:50 -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 , Nick Hu , 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 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 v3 02/25] notifier: Add blocking_notifier_call_chain_is_empty() Date: Mon, 8 Nov 2021 03:45:01 +0300 Message-Id: <20211108004524.29465-3-digetx@gmail.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211108004524.29465-1-digetx@gmail.com> References: <20211108004524.29465-1-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 | 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!