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Date: Mon, 31 Jan 2022 02:36:59 +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>,
Sebastian Reichel <sre@...nel.org>,
Linus Walleij <linus.walleij@...aro.org>,
Philipp Zabel <p.zabel@...gutronix.de>,
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>, alankao@...estech.com,
"K . C . Kuen-Chern Lin" <kclin@...estech.com>,
Michał Mirosław <mirq-linux@...e.qmqm.pl>
Cc: 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,
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 v6 02/21] notifier: Add atomic/blocking_notifier_chain_register_unique_prio()
Add variant of atomic/blocking_notifier_chain_register() functions that
doesn't allow to register notifier using a duplicated priority. The -EBUSY
error code is returned in this case by the new API functions.
Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
include/linux/notifier.h | 5 +++
kernel/notifier.c | 88 +++++++++++++++++++++++++++++++---------
2 files changed, 74 insertions(+), 19 deletions(-)
diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index d4717bc0ab85..ccce26197dd2 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -150,6 +150,11 @@ extern int raw_notifier_chain_register(struct raw_notifier_head *nh,
extern int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
struct notifier_block *nb);
+extern int atomic_notifier_chain_register_unique_prio(
+ struct atomic_notifier_head *nh, struct notifier_block *nb);
+extern int blocking_notifier_chain_register_unique_prio(
+ struct blocking_notifier_head *nh, struct notifier_block *nb);
+
extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
struct notifier_block *nb);
extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
diff --git a/kernel/notifier.c b/kernel/notifier.c
index 4ed6bda8f127..4fc32b1e6cbb 100644
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -20,7 +20,8 @@ BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
*/
static int notifier_chain_register(struct notifier_block **nl,
- struct notifier_block *n)
+ struct notifier_block *n,
+ bool unique_priority)
{
while ((*nl) != NULL) {
if (unlikely((*nl) == n)) {
@@ -30,6 +31,8 @@ static int notifier_chain_register(struct notifier_block **nl,
}
if (n->priority > (*nl)->priority)
break;
+ if (n->priority == (*nl)->priority && unique_priority)
+ return -EBUSY;
nl = &((*nl)->next);
}
n->next = *nl;
@@ -144,12 +147,35 @@ int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
int ret;
spin_lock_irqsave(&nh->lock, flags);
- ret = notifier_chain_register(&nh->head, n);
+ ret = notifier_chain_register(&nh->head, n, false);
spin_unlock_irqrestore(&nh->lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);
+/**
+ * atomic_notifier_chain_register_unique_prio - Add notifier to an atomic notifier chain
+ * @nh: Pointer to head of the atomic notifier chain
+ * @n: New entry in notifier chain
+ *
+ * Adds a notifier to an atomic notifier chain if there is no other
+ * notifier registered using the same priority.
+ *
+ * Returns 0 on success, %-EEXIST or %-EBUSY on error.
+ */
+int atomic_notifier_chain_register_unique_prio(struct atomic_notifier_head *nh,
+ struct notifier_block *n)
+{
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&nh->lock, flags);
+ ret = notifier_chain_register(&nh->head, n, true);
+ spin_unlock_irqrestore(&nh->lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(atomic_notifier_chain_register_unique_prio);
+
/**
* atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain
* @nh: Pointer to head of the atomic notifier chain
@@ -209,18 +235,9 @@ NOKPROBE_SYMBOL(atomic_notifier_call_chain);
* synchronized by an rwsem.
*/
-/**
- * blocking_notifier_chain_register - Add notifier to a blocking notifier chain
- * @nh: Pointer to head of the blocking notifier chain
- * @n: New entry in notifier chain
- *
- * Adds a notifier to a blocking notifier chain.
- * Must be called in process context.
- *
- * Returns 0 on success, %-EEXIST on error.
- */
-int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
- struct notifier_block *n)
+static int __blocking_notifier_chain_register(struct blocking_notifier_head *nh,
+ struct notifier_block *n,
+ bool unique_priority)
{
int ret;
@@ -230,15 +247,48 @@ int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
* such times we must not call down_write().
*/
if (unlikely(system_state == SYSTEM_BOOTING))
- return notifier_chain_register(&nh->head, n);
+ return notifier_chain_register(&nh->head, n, unique_priority);
down_write(&nh->rwsem);
- ret = notifier_chain_register(&nh->head, n);
+ ret = notifier_chain_register(&nh->head, n, unique_priority);
up_write(&nh->rwsem);
return ret;
}
+
+/**
+ * blocking_notifier_chain_register - Add notifier to a blocking notifier chain
+ * @nh: Pointer to head of the blocking notifier chain
+ * @n: New entry in notifier chain
+ *
+ * Adds a notifier to a blocking notifier chain.
+ * Must be called in process context.
+ *
+ * Returns 0 on success, %-EEXIST on error.
+ */
+int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
+ struct notifier_block *n)
+{
+ return __blocking_notifier_chain_register(nh, n, false);
+}
EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
+/**
+ * blocking_notifier_chain_register_unique_prio - Add notifier to a blocking notifier chain
+ * @nh: Pointer to head of the blocking notifier chain
+ * @n: New entry in notifier chain
+ *
+ * Adds a notifier to an blocking notifier chain if there is no other
+ * notifier registered using the same priority.
+ *
+ * Returns 0 on success, %-EEXIST or %-EBUSY on error.
+ */
+int blocking_notifier_chain_register_unique_prio(struct blocking_notifier_head *nh,
+ struct notifier_block *n)
+{
+ return __blocking_notifier_chain_register(nh, n, true);
+}
+EXPORT_SYMBOL_GPL(blocking_notifier_chain_register_unique_prio);
+
/**
* blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
* @nh: Pointer to head of the blocking notifier chain
@@ -354,7 +404,7 @@ bool blocking_notifier_call_chain_is_empty(struct blocking_notifier_head *nh)
int raw_notifier_chain_register(struct raw_notifier_head *nh,
struct notifier_block *n)
{
- return notifier_chain_register(&nh->head, n);
+ return notifier_chain_register(&nh->head, n, false);
}
EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
@@ -433,10 +483,10 @@ int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
* such times we must not call mutex_lock().
*/
if (unlikely(system_state == SYSTEM_BOOTING))
- return notifier_chain_register(&nh->head, n);
+ return notifier_chain_register(&nh->head, n, false);
mutex_lock(&nh->mutex);
- ret = notifier_chain_register(&nh->head, n);
+ ret = notifier_chain_register(&nh->head, n, false);
mutex_unlock(&nh->mutex);
return ret;
}
--
2.34.1
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