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Date: Mon, 8 Nov 2021 03:45:02 +0300
From: Dmitry Osipenko <digetx@...il.com>
To: Thierry Reding <thierry.reding@...il.com>,
Jonathan Hunter <jonathanh@...dia.com>,
Russell King <linux@...linux.org.uk>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>, Guo Ren <guoren@...nel.org>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Greg Ungerer <gerg@...ux-m68k.org>,
Joshua Thompson <funaho@...ai.org>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Nick Hu <nickhu@...estech.com>,
Greentime Hu <green.hu@...il.com>,
Vincent Chen <deanbo422@...il.com>,
"James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
Helge Deller <deller@....de>,
Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>,
Rich Felker <dalias@...c.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>,
Stefano Stabellini <sstabellini@...nel.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Len Brown <lenb@...nel.org>,
Santosh Shilimkar <ssantosh@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
Liam Girdwood <lgirdwood@...il.com>,
Mark Brown <broonie@...nel.org>, Pavel Machek <pavel@....cz>,
Lee Jones <lee.jones@...aro.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Guenter Roeck <linux@...ck-us.net>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Ulf Hansson <ulf.hansson@...aro.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-csky@...r.kernel.org, linux-ia64@...r.kernel.org,
linux-m68k@...ts.linux-m68k.org, linux-mips@...r.kernel.org,
linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-riscv@...ts.infradead.org, linux-sh@...r.kernel.org,
xen-devel@...ts.xenproject.org, linux-acpi@...r.kernel.org,
linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: [PATCH v3 03/25] notifier: Add atomic/blocking_notifier_has_unique_priority()
Add atomic/blocking_notifier_has_unique_priority() helpers which return
true if given handler has unique priority.
Signed-off-by: Dmitry Osipenko <digetx@...il.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
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