[PATCH] iommu/rockchip: Don't provoke WARN for harmless IRQs

[PATCH] iommu/rockchip: Don't provoke WARN for harmless IRQs

[Robin Murphy]

Although we don't generally expect IRQs to fire for a suspended IOMMU,
there are certain situations (particularly with debug options) where
we might legitimately end up with the pm_runtime_get_if_in_use() call
from rk_iommu_irq() returning 0. Since this doesn't represent an actual
error, follow the other parts of the driver and save the WARN_ON()
condition for a genuine negative value. Even if we do have spurious
IRQs due to a wedged VOP asserting the shared line, it's not this
driver's job to try to second-guess the IRQ core to warn about that.

Reported-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/iommu/rockchip-iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index 4dcbf68dfda4..bd7e9b1e40ac 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -527,7 +527,7 @@ static irqreturn_t rk_iommu_irq(int irq, void *dev_id)
 	int i, err;
 
 	err = pm_runtime_get_if_in_use(iommu->dev);
-	if (WARN_ON_ONCE(err <= 0))
+	if (!err || WARN_ON_ONCE(err < 0))
 		return ret;
 
 	if (WARN_ON(clk_bulk_enable(iommu->num_clocks, iommu->clocks)))
-- 
2.20.1

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Re: [PATCH] iommu/rockchip: Don't provoke WARN for harmless IRQs

[Marc Zyngier]

On 2019-11-11 20:04, Robin Murphy wrote:
> Although we don't generally expect IRQs to fire for a suspended 
> IOMMU,
> there are certain situations (particularly with debug options) where
> we might legitimately end up with the pm_runtime_get_if_in_use() call
> from rk_iommu_irq() returning 0. Since this doesn't represent an 
> actual
> error, follow the other parts of the driver and save the WARN_ON()
> condition for a genuine negative value. Even if we do have spurious
> IRQs due to a wedged VOP asserting the shared line, it's not this
> driver's job to try to second-guess the IRQ core to warn about that.
>
> Reported-by: Vasily Khoruzhick <anarsoul@gmail.com>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  drivers/iommu/rockchip-iommu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/rockchip-iommu.c 
> b/drivers/iommu/rockchip-iommu.c
> index 4dcbf68dfda4..bd7e9b1e40ac 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
> @@ -527,7 +527,7 @@ static irqreturn_t rk_iommu_irq(int irq, void 
> *dev_id)
>  	int i, err;
>
>  	err = pm_runtime_get_if_in_use(iommu->dev);
> -	if (WARN_ON_ONCE(err <= 0))
> +	if (!err || WARN_ON_ONCE(err < 0))
>  		return ret;
>
>  	if (WARN_ON(clk_bulk_enable(iommu->num_clocks, iommu->clocks)))

Acked-by: Marc Zyngier <maz@kernel.org>

         M.
-- 
Jazz is not dead. It just smells funny...
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Re: [PATCH] iommu/rockchip: Don't provoke WARN for harmless IRQs

[Joerg Roedel]

On Mon, Nov 11, 2019 at 06:55:18PM +0000, Robin Murphy wrote:
> Although we don't generally expect IRQs to fire for a suspended IOMMU,
> there are certain situations (particularly with debug options) where
> we might legitimately end up with the pm_runtime_get_if_in_use() call
> from rk_iommu_irq() returning 0. Since this doesn't represent an actual
> error, follow the other parts of the driver and save the WARN_ON()
> condition for a genuine negative value. Even if we do have spurious
> IRQs due to a wedged VOP asserting the shared line, it's not this
> driver's job to try to second-guess the IRQ core to warn about that.
> 
> Reported-by: Vasily Khoruzhick <anarsoul@gmail.com>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  drivers/iommu/rockchip-iommu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied, thanks.
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