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[46.138.41.28]) by smtp.gmail.com with ESMTPSA id d7sm104336ljl.18.2021.10.27.14.17.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Oct 2021 14:17:57 -0700 (PDT) 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: 92f7f69c-ba4d-45e9-915e-e2b0259386cd 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=gfPQe0zgS4I4UWFZNFBbY1KeZFawP+pEpuBLVF6wdKM=; b=IF53pE4MG8dtqJfDztqJu8/A7a/y14/j36v2nKdiMw6iu4DWmrRW8MOeE8LURQLXaK Ga0+xYwPRFyxojC/znNrOvpLGs+k6KHlhVWadULFKWtX+mXFusF6mHh4CLs+vcnkJVbI sCT8nKeVlZGK2TnNZ10Uo/TFQPsaFWopDEGJma2V9OokstL1aGUJunbAvrHKFFxOtEwg lD8/h9mw7UJrhz8Lza29Xoci0CHBwnwZJdD56IRSRRGiIs4vKcta6w27872hpSmyCu02 ZBL1gjD87s9mbzpJUGm1Sbte3r8qhTN12pgeySe/LAcZyKJ0wXtrJhOtFLQB3UvQJ2Q1 ctBg== 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=gfPQe0zgS4I4UWFZNFBbY1KeZFawP+pEpuBLVF6wdKM=; b=64LdfLFdyNs9FIPPEP7qdkbVqEL93mZAkB9Tc8XfpIuWXw+Lydsq4mT3ttKfHdDIAY 66A3gSoTk3+P98ft+5eBhowddOwiahM8qwr0wjdftq6FuH6fLEBy+o2f+jFI4RyY7g5H Jucn37Aj6V5gTLwWHr6XASacoboBrnxJ5iNQlUf1pLqEdhGHLvaJ7Z1bydOGpCx53D/m E96VXOb2jM7emsXlvF+T/fsjexp6Hn1/7TcfpmqihZE6Vg5JmF13rbIpCkzkycKi05kw kYoMYxO8s+bimz5v0gs+WsuWiJO2bQI6lJ9CbMMN7saWgR/pHM72MiogG5k2d7pLVGJ3 zMTQ== X-Gm-Message-State: AOAM531v933gp1gYyJVSW4wA4r336AucWFC+dISX9Z3ldhyRuHtaH12k akfYXo7Z0oWrtaMVrTVna5o= X-Google-Smtp-Source: ABdhPJxkIyEtMiQViKWR5fwy6fiT3tpzf12+F4/RJZJ4BQVHBt5yXcPBTwu2lq74yYNLjaS3GsmWQQ== X-Received: by 2002:a05:6512:1095:: with SMTP id j21mr130850lfg.274.1635369478293; Wed, 27 Oct 2021 14:17:58 -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 03/45] notifier: Add atomic/blocking_notifier_has_unique_priority() Date: Thu, 28 Oct 2021 00:16:33 +0300 Message-Id: <20211027211715.12671-4-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 Add atomic/blocking_notifier_has_unique_priority() helpers which return true if given handler has unique priority. Signed-off-by: Dmitry Osipenko --- include/linux/notifier.h | 5 +++ kernel/notifier.c | 74 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 79 insertions(+) diff --git a/include/linux/notifier.h b/include/linux/notifier.h index 054271e9cb20..b782ce100022 100644 --- a/include/linux/notifier.h +++ b/include/linux/notifier.h @@ -175,6 +175,11 @@ int raw_notifier_call_chain_robust(struct raw_notifier_head *nh, bool blocking_notifier_call_chain_empty(struct blocking_notifier_head *nh); +bool atomic_notifier_has_unique_priority(struct atomic_notifier_head *nh, + struct notifier_block *nb); +bool blocking_notifier_has_unique_priority(struct blocking_notifier_head *nh, + struct notifier_block *nb); + #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 1f7ba8988b90..cf0e1c4bd364 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -203,6 +203,40 @@ int atomic_notifier_call_chain(struct atomic_notifier_head *nh, EXPORT_SYMBOL_GPL(atomic_notifier_call_chain); NOKPROBE_SYMBOL(atomic_notifier_call_chain); +/** + * atomic_notifier_has_unique_priority - Checks whether notifier's priority is unique + * @nh: Pointer to head of the atomic notifier chain + * @n: Entry in notifier chain to check + * + * Checks whether there is another notifier in the chain with the same priority. + * Must be called in process context. + * + * Returns true if priority is unique, false otherwise. + */ +bool atomic_notifier_has_unique_priority(struct atomic_notifier_head *nh, + struct notifier_block *n) +{ + struct notifier_block **nl = &nh->head; + unsigned long flags; + bool ret = true; + + spin_lock_irqsave(&nh->lock, flags); + + while ((*nl) != NULL && (*nl)->priority >= n->priority) { + if ((*nl)->priority == n->priority && (*nl) != n) { + ret = false; + break; + } + + nl = &((*nl)->next); + } + + spin_unlock_irqrestore(&nh->lock, flags); + + return ret; +} +EXPORT_SYMBOL_GPL(atomic_notifier_has_unique_priority); + /* * Blocking notifier chain routines. All access to the chain is * synchronized by an rwsem. @@ -336,6 +370,46 @@ bool blocking_notifier_call_chain_empty(struct blocking_notifier_head *nh) } EXPORT_SYMBOL_GPL(blocking_notifier_call_chain_empty); +/** + * blocking_notifier_has_unique_priority - Checks whether notifier's priority is unique + * @nh: Pointer to head of the blocking notifier chain + * @n: Entry in notifier chain to check + * + * Checks whether there is another notifier in the chain with the same priority. + * Must be called in process context. + * + * Returns true if priority is unique, false otherwise. + */ +bool blocking_notifier_has_unique_priority(struct blocking_notifier_head *nh, + struct notifier_block *n) +{ + struct notifier_block **nl = &nh->head; + bool ret = true; + + /* + * This code gets used during boot-up, when task switching is + * not yet working and interrupts must remain disabled. At + * such times we must not call down_write(). + */ + if (system_state != SYSTEM_BOOTING) + down_write(&nh->rwsem); + + while ((*nl) != NULL && (*nl)->priority >= n->priority) { + if ((*nl)->priority == n->priority && (*nl) != n) { + ret = false; + break; + } + + nl = &((*nl)->next); + } + + if (system_state != SYSTEM_BOOTING) + up_write(&nh->rwsem); + + return ret; +} +EXPORT_SYMBOL_GPL(blocking_notifier_has_unique_priority); + /* * Raw notifier chain routines. There is no protection; * the caller must provide it. Use at your own risk!