linux-kernel - Re: [PATCH 14/15] drm/amd: cleanup: drm_modeset_lock_all() --> DRM_MODESET_LOCK_ALL

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Date:   Sat, 18 Sep 2021 01:17:01 +0200
From:   Fernando Ramos <greenfoo@....eu>
To:     Sean Paul <sean@...rly.run>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        linux-renesas-soc@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH 14/15] drm/amd: cleanup: drm_modeset_lock_all() -->
 DRM_MODESET_LOCK_ALL_BEGIN()

> > +	struct drm_modeset_acquire_ctx ctx;
> >  	int r;
> > +	int ret;
> 
> Relocate ret with r please

Done!

> > -	drm_modeset_unlock_all(dev);
> > +	DRM_MODESET_LOCK_ALL_END(dev, ctx, ret);
> 
> You should check ret here

Done!


> >  	int r;
> > +	int ret;
> 
> Relocate ret with r

Done!


> > -	drm_modeset_unlock_all(dev);
> > +	DRM_MODESET_LOCK_ALL_END(dev, ctx, ret);
> >  
> >  	return 0;
> 
> Return ret

Done!


> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > index 9b1fc54555ee..5196c1d26f87 100644
> > @@ -2661,13 +2657,18 @@ static void handle_hpd_irq(void *param)
> >  
> >  		amdgpu_dm_update_connector_after_detect(aconnector);
> >  
> > -		drm_modeset_lock_all(dev);
> > -		dm_restore_drm_connector_state(dev, connector);
> > -		drm_modeset_unlock_all(dev);
> > -
> > -		if (aconnector->base.force == DRM_FORCE_UNSPECIFIED)
> > -			drm_kms_helper_hotplug_event(dev);
> > +	} else {
> > +		goto out;
> >  	}
> > +
> > +	DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret);
> > +	dm_restore_drm_connector_state(dev, connector);
> > +	DRM_MODESET_LOCK_ALL_END(dev, ctx, ret);
> 
> Check ret here please

This function ("handle_hpd_irq") returns void. What would the appropriate way of
checking the error be?


> > @@ -2841,14 +2838,17 @@ static void handle_hpd_rx_irq(void *param)
> >  
> >  			amdgpu_dm_update_connector_after_detect(aconnector);
> >  
> > +		} else {
> > +			goto finish;
> 
> You used 'out' above and 'finish' here. It would be nice to be consistent with
> naming, I see 'out' a lot more than 'finish', so my vote would be to change this
> label to 'out'.

I originally used "out", but turns out there is already an "out" label in this
function :)

I then searched for other "go to end" labels and found "finish" being used in 
this same file.

But I can rename it to somehitng else ("out2" maybe?) to make it less confusing.

 
> > +		}
> >  
> > -			drm_modeset_lock_all(dev);
> > -			dm_restore_drm_connector_state(dev, connector);
> > -			drm_modeset_unlock_all(dev);
> > +		DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret);
> > +		dm_restore_drm_connector_state(dev, connector);
> > +		DRM_MODESET_LOCK_ALL_END(dev, ctx, ret);
> 
> Check ret here?

This is another irq-like function returning void.

What can we do here after having checked the error?


> > +#include <drm/drm_drv.h>
> 
> Top-level headers generally come above the driver headers. Also, now that I think
> about this a bit more, all of the new includes in this set should probably be
> for 'drm_modeset_lock.h' instead of 'drm_drv.h'.

Ok. Let me try that.


> > @@ -1259,13 +1257,16 @@ static ssize_t trigger_hotplug(struct file *f, const char __user *buf,
> > +	DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret);
> > +	dm_restore_drm_connector_state(dev, connector);
> > +	DRM_MODESET_LOCK_ALL_END(dev, ctx, ret);
> 
> Check ret here?

This is a .write file_operations function expected to return a "size". Is it ok
for it to return an error? I guess so, right?