From: Dmitry Osipenko <digetx@gmail•com>
To: Thierry Reding <thierry.reding@gmail•com>,
Jonathan Hunter <jonathanh@nvidia•com>,
Russell King <linux@armlinux•org.uk>,
Catalin Marinas <catalin.marinas@arm•com>,
Will Deacon <will@kernel•org>, Guo Ren <guoren@kernel•org>,
Geert Uytterhoeven <geert@linux-m68k•org>,
Greg Ungerer <gerg@linux-m68k•org>,
Joshua Thompson <funaho@jurai•org>,
Thomas Bogendoerfer <tsbogend@alpha•franken.de>,
Nick Hu <nickhu@andestech•com>, Greentime Hu <green.hu@gmail•com>,
Vincent Chen <deanbo422@gmail•com>,
"James E.J. Bottomley" <James.Bottomley@HansenPartnership•com>,
Helge Deller <deller@gmx•de>,
Michael Ellerman <mpe@ellerman•id.au>,
Benjamin Herrenschmidt <benh@kernel•crashing.org>,
Paul Mackerras <paulus@samba•org>,
Paul Walmsley <paul.walmsley@sifive•com>,
Palmer Dabbelt <palmer@dabbelt•com>,
Albert Ou <aou@eecs•berkeley.edu>,
Yoshinori Sato <ysato@users•sourceforge.jp>,
Rich Felker <dalias@libc•org>,
Thomas Gleixner <tglx@linutronix•de>,
Ingo Molnar <mingo@redhat•com>, Borislav Petkov <bp@alien8•de>,
Dave Hansen <dave.hansen@linux•intel.com>,
x86@kernel•org, "H. Peter Anvin" <hpa@zytor•com>,
Boris Ostrovsky <boris.ostrovsky@oracle•com>,
Juergen Gross <jgross@suse•com>,
Stefano Stabellini <sstabellini@kernel•org>,
"Rafael J. Wysocki" <rafael@kernel•org>,
Len Brown <lenb@kernel•org>,
Santosh Shilimkar <ssantosh@kernel•org>,
Krzysztof Kozlowski <krzysztof.kozlowski@canonical•com>,
Liam Girdwood <lgirdwood@gmail•com>,
Mark Brown <broonie@kernel•org>, Pavel Machek <pavel@ucw•cz>,
Lee Jones <lee.jones@linaro•org>,
Andrew Morton <akpm@linux-foundation•org>,
Guenter Roeck <linux@roeck-us•net>,
Daniel Lezcano <daniel.lezcano@linaro•org>,
Andy Shevchenko <andriy.shevchenko@linux•intel.com>,
Ulf Hansson <ulf.hansson@linaro•org>
Cc: linux-ia64@vger•kernel.org, linux-parisc@vger•kernel.org,
linux-sh@vger•kernel.org, linux-pm@vger•kernel.org,
linux-kernel@vger•kernel.org, linux-csky@vger•kernel.org,
linux-mips@vger•kernel.org, linux-acpi@vger•kernel.org,
linux-m68k@lists•linux-m68k.org, linux-tegra@vger•kernel.org,
xen-devel@lists•xenproject.org, linux-riscv@lists•infradead.org,
linuxppc-dev@lists•ozlabs.org,
linux-arm-kernel@lists•infradead.org
Subject: [PATCH v3 03/25] notifier: Add atomic/blocking_notifier_has_unique_priority()
Date: Mon, 8 Nov 2021 03:45:02 +0300 [thread overview]
Message-ID: <20211108004524.29465-4-digetx@gmail.com> (raw)
In-Reply-To: <20211108004524.29465-1-digetx@gmail.com>
Add atomic/blocking_notifier_has_unique_priority() helpers which return
true if given handler has unique priority.
Signed-off-by: Dmitry Osipenko <digetx@gmail•com>
---
include/linux/notifier.h | 5 +++
kernel/notifier.c | 69 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 74 insertions(+)
diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index 924c9d7c8e73..2c4036f225e1 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_is_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 b20cb7b9b1f0..7a325b742104 100644
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -122,6 +122,19 @@ static int notifier_call_chain_robust(struct notifier_block **nl,
return ret;
}
+static int notifier_has_unique_priority(struct notifier_block **nl,
+ struct notifier_block *n)
+{
+ while (*nl && (*nl)->priority >= n->priority) {
+ if ((*nl)->priority == n->priority && *nl != n)
+ return false;
+
+ nl = &((*nl)->next);
+ }
+
+ return true;
+}
+
/*
* Atomic notifier chain routines. Registration and unregistration
* use a spinlock, and call_chain is synchronized by RCU (no locks).
@@ -203,6 +216,30 @@ 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)
+{
+ unsigned long flags;
+ bool ret;
+
+ spin_lock_irqsave(&nh->lock, flags);
+ ret = notifier_has_unique_priority(&nh->head, n);
+ 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 +373,38 @@ bool blocking_notifier_call_chain_is_empty(struct blocking_notifier_head *nh)
}
EXPORT_SYMBOL_GPL(blocking_notifier_call_chain_is_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)
+{
+ bool ret;
+
+ /*
+ * 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_read().
+ */
+ if (system_state != SYSTEM_BOOTING)
+ down_read(&nh->rwsem);
+
+ ret = notifier_has_unique_priority(&nh->head, n);
+
+ if (system_state != SYSTEM_BOOTING)
+ up_read(&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!
--
2.33.1
next prev parent reply other threads:[~2021-11-08 0:50 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-08 0:44 [PATCH v3 00/25] Introduce power-off+restart call chain API Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 01/25] notifier: Remove extern annotation from function prototypes Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 02/25] notifier: Add blocking_notifier_call_chain_is_empty() Dmitry Osipenko
2021-11-08 0:45 ` Dmitry Osipenko [this message]
2021-11-08 0:45 ` [PATCH v3 04/25] reboot: Correct typo in a comment Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 05/25] reboot: Warn if restart handler has duplicated priority Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 06/25] reboot: Warn if unregister_restart_handler() fails Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 07/25] reboot: Remove extern annotation from function prototypes Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 08/25] kernel: Add combined power-off+restart handler call chain API Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 09/25] ARM: Use do_kernel_power_off() Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 10/25] csky: " Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 11/25] riscv: " Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 12/25] arm64: " Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 13/25] parisc: " Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 14/25] xen/x86: " Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 15/25] sh: " Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 16/25] x86: " Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 17/25] ia64: " Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 18/25] mips: " Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 19/25] nds32: " Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 20/25] powerpc: " Dmitry Osipenko
2021-11-08 12:01 ` Michael Ellerman
2021-11-08 0:45 ` [PATCH v3 21/25] m68k: Switch to new sys-off handler API Dmitry Osipenko
2021-11-08 7:47 ` Geert Uytterhoeven
2021-11-08 0:45 ` [PATCH v3 22/25] memory: emif: Use kernel_can_power_off() Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 23/25] ACPI: power: Switch to sys-off handler API Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 24/25] regulator: pfuze100: Use devm_register_sys_off_handler() Dmitry Osipenko
2021-11-08 0:45 ` [PATCH v3 25/25] reboot: Remove pm_power_off_prepare() Dmitry Osipenko
2021-11-08 1:14 ` [PATCH v3 00/25] Introduce power-off+restart call chain API Dmitry Osipenko
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