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Message-ID: <tip-02cea3958664723a5d2236f0f0058de97c7e4693@git.kernel.org>
Date: Wed, 18 Feb 2015 09:08:42 -0800
From: tip-bot for Peter Zijlstra <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: lambert.quentin@...il.com, arnd@...db.de, peterz@...radead.org,
mingo@...nel.org, rdunlap@...radead.org, sd@...asysnail.net,
linux-kernel@...r.kernel.org, linux@....linux.org.uk,
paulmck@...ux.vnet.ibm.com, hpa@...or.com, tglx@...utronix.de,
davem@...emloft.net, torvalds@...ux-foundation.org,
eyalpe@...lanox.com
Subject: [tip:irq/core] genirq: Provide disable_hardirq()
Commit-ID: 02cea3958664723a5d2236f0f0058de97c7e4693
Gitweb: http://git.kernel.org/tip/02cea3958664723a5d2236f0f0058de97c7e4693
Author: Peter Zijlstra <peterz@...radead.org>
AuthorDate: Thu, 5 Feb 2015 14:06:23 +0100
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 18 Feb 2015 15:08:33 +0100
genirq: Provide disable_hardirq()
For things like netpoll there is a need to disable an interrupt from
atomic context. Currently netpoll uses disable_irq() which will
sleep-wait on threaded handlers and thus forced_irqthreads breaks
things.
Provide disable_hardirq(), which uses synchronize_hardirq() to only wait
for active hardirq handlers; also change synchronize_hardirq() to
return the status of threaded handlers.
This will allow one to try-disable an interrupt from atomic context, or
in case of request_threaded_irq() to only wait for the hardirq part.
Suggested-by: Sabrina Dubroca <sd@...asysnail.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: David Miller <davem@...emloft.net>
Cc: Eyal Perry <eyalpe@...lanox.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Quentin Lambert <lambert.quentin@...il.com>
Cc: Randy Dunlap <rdunlap@...radead.org>
Cc: Russell King <linux@....linux.org.uk>
Link: http://lkml.kernel.org/r/20150205130623.GH5029@twins.programming.kicks-ass.net
[ Fixed typos and such. ]
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
include/linux/hardirq.h | 2 +-
include/linux/interrupt.h | 1 +
kernel/irq/manage.c | 36 ++++++++++++++++++++++++++++++++++--
3 files changed, 36 insertions(+), 3 deletions(-)
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index cba442e..f4af034 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -9,7 +9,7 @@
extern void synchronize_irq(unsigned int irq);
-extern void synchronize_hardirq(unsigned int irq);
+extern bool synchronize_hardirq(unsigned int irq);
#if defined(CONFIG_TINY_RCU)
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index d9b05b5..3bb01b9 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -184,6 +184,7 @@ extern void devm_free_irq(struct device *dev, unsigned int irq, void *dev_id);
#endif
extern void disable_irq_nosync(unsigned int irq);
+extern bool disable_hardirq(unsigned int irq);
extern void disable_irq(unsigned int irq);
extern void disable_percpu_irq(unsigned int irq);
extern void enable_irq(unsigned int irq);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 196a06f..03329c2 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -68,14 +68,20 @@ static void __synchronize_hardirq(struct irq_desc *desc)
* Do not use this for shutdown scenarios where you must be sure
* that all parts (hardirq and threaded handler) have completed.
*
+ * Returns: false if a threaded handler is active.
+ *
* This function may be called - with care - from IRQ context.
*/
-void synchronize_hardirq(unsigned int irq)
+bool synchronize_hardirq(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
- if (desc)
+ if (desc) {
__synchronize_hardirq(desc);
+ return !atomic_read(&desc->threads_active);
+ }
+
+ return true;
}
EXPORT_SYMBOL(synchronize_hardirq);
@@ -440,6 +446,32 @@ void disable_irq(unsigned int irq)
}
EXPORT_SYMBOL(disable_irq);
+/**
+ * disable_hardirq - disables an irq and waits for hardirq completion
+ * @irq: Interrupt to disable
+ *
+ * Disable the selected interrupt line. Enables and Disables are
+ * nested.
+ * This function waits for any pending hard IRQ handlers for this
+ * interrupt to complete before returning. If you use this function while
+ * holding a resource the hard IRQ handler may need you will deadlock.
+ *
+ * When used to optimistically disable an interrupt from atomic context
+ * the return value must be checked.
+ *
+ * Returns: false if a threaded handler is active.
+ *
+ * This function may be called - with care - from IRQ context.
+ */
+bool disable_hardirq(unsigned int irq)
+{
+ if (!__disable_irq_nosync(irq))
+ return synchronize_hardirq(irq);
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(disable_hardirq);
+
void __enable_irq(struct irq_desc *desc, unsigned int irq)
{
switch (desc->depth) {
--
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