Alex,
On 08/12/2015 08:56 PM, Alex Williamson wrote:
> On Mon, 2015-08-10 at 15:20 +0200, Eric Auger wrote:
>> A single handler now is registered whatever the use case: automasked
>> or not. A function pointer is set according to the wished behavior
>> and the handler calls this function.
>>
>> The irq lock is taken/released in the root handler. eventfd_signal can
>> be called in regions not allowed to sleep.
>>
>> Signed-off-by: Eric Auger <eric.au...@linaro.org>
>>
>> ---
>>
>> v4: creation
>> ---
>> drivers/vfio/platform/vfio_platform_irq.c | 21 +++++++++++++++------
>> drivers/vfio/platform/vfio_platform_private.h | 1 +
>> 2 files changed, 16 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/vfio/platform/vfio_platform_irq.c
>> b/drivers/vfio/platform/vfio_platform_irq.c
>> index 40f057a..b31b1f0 100644
>> --- a/drivers/vfio/platform/vfio_platform_irq.c
>> +++ b/drivers/vfio/platform/vfio_platform_irq.c
>> @@ -148,11 +148,8 @@ static int vfio_platform_set_irq_unmask(struct
>> vfio_platform_device *vdev,
>> static irqreturn_t vfio_automasked_irq_handler(int irq, void *dev_id)
>> {
>> struct vfio_platform_irq *irq_ctx = dev_id;
>> - unsigned long flags;
>> int ret = IRQ_NONE;
>>
>> - spin_lock_irqsave(&irq_ctx->lock, flags);
>> -
>> if (!irq_ctx->masked) {
>> ret = IRQ_HANDLED;
>>
>> @@ -161,8 +158,6 @@ static irqreturn_t vfio_automasked_irq_handler(int irq,
>> void *dev_id)
>> irq_ctx->masked = true;
>> }
>>
>> - spin_unlock_irqrestore(&irq_ctx->lock, flags);
>> -
>> if (ret == IRQ_HANDLED)
>> eventfd_signal(irq_ctx->trigger, 1);
>
> Has this been run with lockdep to check whether this is safe to call
> with spinlock_irqsave held?
No I did not check with lockdep and I will do. There is a comment in
fs/eventfd.c in eventfd_signal function comments that says:
"This function is supposed to be called by the kernel in paths that do
not allow sleeping. In this function we allow the counter to reach the
ULLONG_MAX value, and we signal this as overflow condition by returining
a POLLERR to poll(2)."
so I understood from this it is safe.
Best Regards
Eric
>
>>
>> @@ -178,6 +173,19 @@ static irqreturn_t vfio_irq_handler(int irq, void
>> *dev_id)
>> return IRQ_HANDLED;
>> }
>>
>> +static irqreturn_t vfio_handler(int irq, void *dev_id)
>> +{
>> + struct vfio_platform_irq *irq_ctx = dev_id;
>> + unsigned long flags;
>> + irqreturn_t ret;
>> +
>> + spin_lock_irqsave(&irq_ctx->lock, flags);
>> + ret = irq_ctx->handler(irq, dev_id);
>> + spin_unlock_irqrestore(&irq_ctx->lock, flags);
>> +
>> + return ret;
>> +}
>> +
>> static void vfio_platform_irq_bypass_stop(struct irq_bypass_producer *prod)
>> {
>> }
>> @@ -229,9 +237,10 @@ static int vfio_set_trigger(struct vfio_platform_device
>> *vdev, int index,
>> }
>>
>> irq->trigger = trigger;
>> + irq->handler = handler;
>>
>> irq_set_status_flags(irq->hwirq, IRQ_NOAUTOEN);
>> - ret = request_irq(irq->hwirq, handler, 0, irq->name, irq);
>> + ret = request_irq(irq->hwirq, vfio_handler, 0, irq->name, irq);
>> if (ret) {
>> kfree(irq->name);
>> eventfd_ctx_put(trigger);
>> diff --git a/drivers/vfio/platform/vfio_platform_private.h
>> b/drivers/vfio/platform/vfio_platform_private.h
>> index 8b4f814..f848a6b 100644
>> --- a/drivers/vfio/platform/vfio_platform_private.h
>> +++ b/drivers/vfio/platform/vfio_platform_private.h
>> @@ -40,6 +40,7 @@ struct vfio_platform_irq {
>> struct virqfd *mask;
>> struct irq_bypass_producer producer;
>> bool forwarded;
>> + irqreturn_t (*handler)(int irq, void *dev_id);
>> };
>>
>> struct vfio_platform_region {
>
>
>
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