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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@queasysnail.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Miller <davem@davemloft.net>
Cc: Eyal Perry <eyalpe@mellanox.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Quentin Lambert <lambert.quentin@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Russell King <linux@arm.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@kernel.org>
This commit is contained in:
Peter Zijlstra 2015-02-05 14:06:23 +01:00 committed by Ingo Molnar
parent 4fe7ffb7e1
commit 02cea39586
3 changed files with 36 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/hardirq.h
View File

@ -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)

1
include/linux/interrupt.h
View File

@ -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);

36
kernel/irq/manage.c
View File

@ -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) {