linux-kernel - Re: [PATCH] vfio/platform: Replace spin_lock_irqsave by spin

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Date:   Tue, 13 Oct 2020 15:32:29 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Tian Tao <tiantao6@...ilicon.com>
Cc:     <eric.auger@...hat.com>, <cohuck@...hat.com>,
        <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <song.bao.hua@...ilicon.com>, <linuxarm@...wei.com>
Subject: Re: [PATCH] vfio/platform: Replace spin_lock_irqsave by spin_lock
 in hard IRQ

On Tue, 13 Oct 2020 10:00:58 +0800
Tian Tao <tiantao6@...ilicon.com> wrote:

> It is redundant to do irqsave and irqrestore in hardIRQ context.

But this function is also called from non-IRQ context.  Thanks,

Alex
 
> Signed-off-by: Tian Tao <tiantao6@...ilicon.com>
> ---
>  drivers/vfio/platform/vfio_platform_irq.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> index c5b09ec..24fd6c5 100644
> --- a/drivers/vfio/platform/vfio_platform_irq.c
> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> @@ -139,10 +139,9 @@ 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);
> +	spin_lock(&irq_ctx->lock);
>  
>  	if (!irq_ctx->masked) {
>  		ret = IRQ_HANDLED;
> @@ -152,7 +151,7 @@ static irqreturn_t vfio_automasked_irq_handler(int irq, void *dev_id)
>  		irq_ctx->masked = true;
>  	}
>  
> -	spin_unlock_irqrestore(&irq_ctx->lock, flags);
> +	spin_unlock(&irq_ctx->lock);
>  
>  	if (ret == IRQ_HANDLED)
>  		eventfd_signal(irq_ctx->trigger, 1);