> -----Original Message----- > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > Sent: Wednesday, October 14, 2020 10:32 AM > To: tiantao (H) <tiantao6@xxxxxxxxxxxxx> > Cc: eric.auger@xxxxxxxxxx; cohuck@xxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; Song Bao Hua (Barry Song) > <song.bao.hua@xxxxxxxxxxxxx>; Linuxarm <linuxarm@xxxxxxxxxx> > 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@xxxxxxxxxxxxx> wrote: > > > It is redundant to do irqsave and irqrestore in hardIRQ context. > > But this function is also called from non-IRQ context. Thanks, It seems you mean vfio_platform_set_irqs_ioctl() -> vfio_platform_set_irq_trigger -> handler() ? so, will it be better to move the irqsave out of the vfio_automasked_irq_handler() and put it to where the function is called in non-IRQ context? I mean: irqhandler() { spin_lock() //without irqsave spin_unlock() } Non-irq context which is calling this handler: irqsave(); irqhandler(); irqrestore(); Anyway, if it is called in IRQ context, it is redundant to do irqsave. > > Alex > > > Signed-off-by: Tian Tao <tiantao6@xxxxxxxxxxxxx> > > --- > > 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); Thanks Barry
