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genirq: Provide disable_hardirq()

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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 <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: David Miller <[email protected]>
Cc: Eyal Perry <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Quentin Lambert <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Russell King <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
[ Fixed typos and such. ]
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Peter Zijlstra 2015-02-05 14:06:23 +01:00 • committed by Ingo Molnar
commit 02cea39586
3 changed files with 36 additions and 3 deletions
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36
kernel/irq/manage.c
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@ -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) {