Am 12.12.2010 17:53, Thomas Gleixner wrote:
> On Sun, 12 Dec 2010, Jan Kiszka wrote:
>
>> From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
>>
>> This enabled interrupt handlers to retrieve the current line sharing state via
>> the new interrupt status word so that they can adapt to it.
>>
>> The switch from shared to exclusive is generally uncritical and can thus be
>> performed on demand. However, preparing a line for shared mode may require
>> preparational steps of the currently registered handler. It can therefore
>> request an ahead-of-time notification via IRQF_ADAPTIVE. The notification
>> consists of an exceptional handler invocation with IRQS_MAKE_SHAREABLE set in
>> the status word.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
>> ---
>> include/linux/interrupt.h | 10 ++++++++++
>> include/linux/irqdesc.h | 2 ++
>> kernel/irq/irqdesc.c | 2 ++
>> kernel/irq/manage.c | 44 +++++++++++++++++++++++++++++++++++++++++---
>> 4 files changed, 55 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
>> index 16cdbbf..c6323a2 100644
>> --- a/include/linux/interrupt.h
>> +++ b/include/linux/interrupt.h
>> @@ -55,6 +55,7 @@
>> * Used by threaded interrupts which need to keep the
>> * irq line disabled until the threaded handler has been run.
>> * IRQF_NO_SUSPEND - Do not disable this IRQ during suspend
>> + * IRQF_ADAPTIVE - Request notification about upcoming interrupt line sharing
>> *
>> */
>> #define IRQF_DISABLED 0x00000020
>> @@ -67,6 +68,7 @@
>> #define IRQF_IRQPOLL 0x00001000
>> #define IRQF_ONESHOT 0x00002000
>> #define IRQF_NO_SUSPEND 0x00004000
>> +#define IRQF_ADAPTIVE 0x00008000
>>
>> #define IRQF_TIMER (__IRQF_TIMER | IRQF_NO_SUSPEND)
>>
>> @@ -126,6 +128,14 @@ struct irqaction {
>>
>> extern irqreturn_t no_action(int cpl, void *dev_id);
>>
>> +/*
>> + * Driver-readable IRQ line status flags:
>> + * IRQS_SHARED - line is shared between multiple handlers
>> + * IRQS_MAKE_SHAREABLE - in the process of making an exclusive line shareable
>> + */
>> +#define IRQS_SHARED 0x00000001
>> +#define IRQS_MAKE_SHAREABLE 0x00000002
>> +
>> extern unsigned long get_irq_status(unsigned long irq);
>>
>> #ifdef CONFIG_GENERIC_HARDIRQS
>> diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
>> index 979c68c..c490e83 100644
>> --- a/include/linux/irqdesc.h
>> +++ b/include/linux/irqdesc.h
>> @@ -29,6 +29,7 @@ struct timer_rand_state;
>> * @wait_for_threads: wait queue for sync_irq to wait for threaded handlers
>> * @dir: /proc/irq/ procfs entry
>> * @name: flow handler name for /proc/interrupts output
>> + * @register_lock: protects registration & release, for unshared->shared
>
> I think we can make that a global mutex. request/free_irq are not
> hotpath operations which require a mutex per irq descriptor.
>
Agreed, will change this.
Jan
Attachment:
signature.asc
Description: OpenPGP digital signature
