Re: [PATCH] drm/hisilicon: Remove redundant null check

[tiantao (H)]

在 2020/11/2 17:03, Thomas Zimmermann 写道:
> Hi
>
> Am 02.11.20 um 09:46 schrieb tiantao (H):
> > 在 2020/11/2 16:32, Thomas Zimmermann 写道:
> > > Hi
> > >
> > > Am 30.10.20 um 10:27 schrieb Tian Tao:
> > > > drm_irq_uninstall can handle the case where dev->irq_enable is false,
> > > > so Remove redundant null check.
> > > >
> > > > Signed-off-by: Tian Tao <tiantao6@xxxxxxxxxxxxx>
> > > > ---
> > > >    drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c | 6 +++---
> > > >    1 file changed, 3 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> > > > b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> > > > index 0c1b40d..b71589b1 100644
> > > > --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> > > > +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> > > > @@ -246,13 +246,13 @@ static int hibmc_unload(struct drm_device *dev)
> > > >          drm_atomic_helper_shutdown(dev);
> > > >    -    if (dev->irq_enabled)
> > > > -        drm_irq_uninstall(dev);
> > > > -
> > > > +    drm_irq_uninstall(dev);
> > >
> > > Removing this check would at least result in an error, [1] so rather
> > > leave it in for now.
> > Now there seems to be no driver to check the return value of
> > drm_irq_uninstall
>
> True. No clean-up code should ever fail. But currently, it's not handled
> by drm_irq_uninstall().
>
> A better fix would be to have drm_irq_uninstall() return early with a
> warning if IRQs are disabled. And for most drivers, a managed version of
> drm_irq_install() would be useful.
Codes like the following
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 09d6e9e..572357c 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -172,6 +172,9 @@ int drm_irq_uninstall(struct drm_device *dev)
        bool irq_enabled;
        int i;

+       if(!dev->irq_enabled || !dev)
+               return 0;
> Best regards
> Thomas
>
> > > Instead, we could discuss if drm_irq_install() should become a managed
> > > interface.
> >
> > Codes like the following
> > diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
> > index 09d6e9e..572357c 100644
> > --- a/drivers/gpu/drm/drm_irq.c
> > +++ b/drivers/gpu/drm/drm_irq.c
> > @@ -172,6 +172,9 @@ int drm_irq_uninstall(struct drm_device *dev)
> >          bool irq_enabled;
> >          int i;
> >
> > +       if(!dev->irq_enabled || !dev)
> > +               return 0;
> >
> > > Best regards
> > > Thomas
> > >
> > > [1]
> > > https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/drm_irq.c#L201
> > >
> > >
> > > >        pci_disable_msi(dev->pdev);
> > > > +
> > > >        hibmc_kms_fini(priv);
> > > >        hibmc_mm_fini(priv);
> > > >        dev->dev_private = NULL;
> > > > +
> > > >        return 0;
> > > >    }
> > > >