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[46.138.41.28]) by smtp.gmail.com with ESMTPSA id d7sm104336ljl.18.2021.10.27.14.17.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Oct 2021 14:17:56 -0700 (PDT) From: Dmitry Osipenko To: Thierry Reding , Jonathan Hunter , Lee Jones , "Rafael J . Wysocki" , Mark Brown , Andrew Morton , Guenter Roeck , Russell King , Daniel Lezcano , Andy Shevchenko , Ulf Hansson Cc: 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 , Len Brown , Santosh Shilimkar , Krzysztof Kozlowski , Linus Walleij , Chen-Yu Tsai , =?utf-8?q?Jonathan_Neusch=C3=A4fer?= , Tony Lindgren , Liam Girdwood , Philipp Zabel , Vladimir Zapolskiy , Avi Fishman , Tomer Maimon , Tali Perry , Patrick Venture , Nancy Yuen , Benjamin Fair , Pavel Machek , 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-omap@vger.kernel.org, openbmc@lists.ozlabs.org, linux-tegra@vger.kernel.org, linux-pm@vger.kernel.org Subject: [PATCH v2 02/45] notifier: Add blocking_notifier_call_chain_empty() Date: Thu, 28 Oct 2021 00:16:32 +0300 Message-Id: <20211027211715.12671-3-digetx@gmail.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211027211715.12671-1-digetx@gmail.com> References: <20211027211715.12671-1-digetx@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org Add blocking_notifier_call_chain_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..054271e9cb20 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_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..1f7ba8988b90 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_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_empty(struct blocking_notifier_head *nh) +{ + return !rcu_access_pointer(nh->head); +} +EXPORT_SYMBOL_GPL(blocking_notifier_call_chain_empty); + /* * Raw notifier chain routines. There is no protection; * the caller must provide it. Use at your own risk!