[PATCH 22/51] drm: manage drm_minor cleanup with drmm_
Daniel Vetter
daniel at ffwll.ch
Mon Mar 16 09:07:32 UTC 2020
On Wed, Mar 11, 2020 at 10:59:10AM +0100, Thomas Zimmermann wrote:
> Hi
>
> Am 02.03.20 um 23:26 schrieb Daniel Vetter:
> > The cleanup here is somewhat tricky, since we can't tell apart the
> > allocated minor index from 0. So register a cleanup action first, and
> > if the index allocation fails, unregister that cleanup action again to
> > avoid bad mistakes.
> >
> > The kdev for the minor already handles NULL, so no problem there.
> >
> > Hence add drmm_remove_action() to the drm_managed library.
> >
> > v2: Make pointer math around void ** consistent with what Laurent
> > suggested.
> >
> > Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > ---
> > drivers/gpu/drm/drm_drv.c | 74 +++++++++++++----------------------
> > drivers/gpu/drm/drm_managed.c | 28 +++++++++++++
> > include/drm/drm_managed.h | 4 ++
> > 3 files changed, 59 insertions(+), 47 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> > index 23e5b0e7e041..29d106195ab3 100644
> > --- a/drivers/gpu/drm/drm_drv.c
> > +++ b/drivers/gpu/drm/drm_drv.c
> > @@ -93,19 +93,35 @@ static struct drm_minor **drm_minor_get_slot(struct drm_device *dev,
> > }
> > }
> >
> > +static void drm_minor_alloc_release(struct drm_device *dev, void *data)
> > +{
> > + struct drm_minor *minor = data;
> > + unsigned long flags;
> > +
> > + put_device(minor->kdev);
> > +
> > + spin_lock_irqsave(&drm_minor_lock, flags);
> > + idr_remove(&drm_minors_idr, minor->index);
> > + spin_unlock_irqrestore(&drm_minor_lock, flags);
> > +}
> > +
> > static int drm_minor_alloc(struct drm_device *dev, unsigned int type)
> > {
> > struct drm_minor *minor;
> > unsigned long flags;
> > int r;
> >
> > - minor = kzalloc(sizeof(*minor), GFP_KERNEL);
> > + minor = drmm_kzalloc(dev, sizeof(*minor), GFP_KERNEL);
> > if (!minor)
> > return -ENOMEM;
> >
> > minor->type = type;
> > minor->dev = dev;
> >
> > + r = drmm_add_action(dev, drm_minor_alloc_release, minor);
> > + if (r)
> > + return r;
> > +
> > idr_preload(GFP_KERNEL);
> > spin_lock_irqsave(&drm_minor_lock, flags);
> > r = idr_alloc(&drm_minors_idr,
> > @@ -116,47 +132,18 @@ static int drm_minor_alloc(struct drm_device *dev, unsigned int type)
> > spin_unlock_irqrestore(&drm_minor_lock, flags);
> > idr_preload_end();
> >
> > - if (r < 0)
> > - goto err_free;
> > + if (r < 0) {
> > + drmm_remove_action(dev, drm_minor_alloc_release, minor);
> > + return r;
> > + }
> >
> > minor->index = r;
> > -
> > minor->kdev = drm_sysfs_minor_alloc(minor);
> > - if (IS_ERR(minor->kdev)) {
> > - r = PTR_ERR(minor->kdev);
> > - goto err_index;
> > - }
> > + if (IS_ERR(minor->kdev))
> > + return PTR_ERR(minor->kdev);
> >
> > *drm_minor_get_slot(dev, type) = minor;
> > return 0;
> > -
> > -err_index:
> > - spin_lock_irqsave(&drm_minor_lock, flags);
> > - idr_remove(&drm_minors_idr, minor->index);
> > - spin_unlock_irqrestore(&drm_minor_lock, flags);
> > -err_free:
> > - kfree(minor);
> > - return r;
> > -}
>
> TBH, I think you're reducing code quality by removing the rollback code
> from init functions, just for the sake of it.
>
> Specifically in this case here, you saved a few lines of code, but the
> overall flow is way more complicated to follow. That's typically a
> reliably source of bugs. This call to drmm_remove_action() just makes it
> worse.
>
> Rather, see my remark on OOP destruction in patch 21. For now, I'd focus
> on the device cleanup and leave init functions as they are.
Ah, I can simplify this with add_action_or_reset. This removes the only
user of drmm_remove_action, which I think is actually a good thing :-)
-Daniel
>
> Best regards
> Thomas
>
> > -
> > -static void drm_minor_free(struct drm_device *dev, unsigned int type)
> > -{
> > - struct drm_minor **slot, *minor;
> > - unsigned long flags;
> > -
> > - slot = drm_minor_get_slot(dev, type);
> > - minor = *slot;
> > - if (!minor)
> > - return;
> > -
> > - put_device(minor->kdev);
> > -
> > - spin_lock_irqsave(&drm_minor_lock, flags);
> > - idr_remove(&drm_minors_idr, minor->index);
> > - spin_unlock_irqrestore(&drm_minor_lock, flags);
> > -
> > - kfree(minor);
> > - *slot = NULL;
> > }
> >
> > static int drm_minor_register(struct drm_device *dev, unsigned int type)
> > @@ -678,16 +665,16 @@ int drm_dev_init(struct drm_device *dev,
> > if (drm_core_check_feature(dev, DRIVER_RENDER)) {
> > ret = drm_minor_alloc(dev, DRM_MINOR_RENDER);
> > if (ret)
> > - goto err_minors;
> > + goto err;
> > }
> >
> > ret = drm_minor_alloc(dev, DRM_MINOR_PRIMARY);
> > if (ret)
> > - goto err_minors;
> > + goto err;
> >
> > ret = drm_legacy_create_map_hash(dev);
> > if (ret)
> > - goto err_minors;
> > + goto err;
> >
> > drm_legacy_ctxbitmap_init(dev);
> >
> > @@ -695,7 +682,7 @@ int drm_dev_init(struct drm_device *dev,
> > ret = drm_gem_init(dev);
> > if (ret) {
> > DRM_ERROR("Cannot initialize graphics execution manager (GEM)\n");
> > - goto err_ctxbitmap;
> > + goto err;
> > }
> > }
> >
> > @@ -708,10 +695,6 @@ int drm_dev_init(struct drm_device *dev,
> > err_setunique:
> > if (drm_core_check_feature(dev, DRIVER_GEM))
> > drm_gem_destroy(dev);
> > -err_ctxbitmap:
> > -err_minors:
> > - drm_minor_free(dev, DRM_MINOR_PRIMARY);
> > - drm_minor_free(dev, DRM_MINOR_RENDER);
> > err:
> > drm_managed_release(dev);
> >
> > @@ -776,9 +759,6 @@ void drm_dev_fini(struct drm_device *dev)
> >
> > if (drm_core_check_feature(dev, DRIVER_GEM))
> > drm_gem_destroy(dev);
> > -
> > - drm_minor_free(dev, DRM_MINOR_PRIMARY);
> > - drm_minor_free(dev, DRM_MINOR_RENDER);
> > }
> > EXPORT_SYMBOL(drm_dev_fini);
> >
> > diff --git a/drivers/gpu/drm/drm_managed.c b/drivers/gpu/drm/drm_managed.c
> > index 514d5bd42446..0883615c2088 100644
> > --- a/drivers/gpu/drm/drm_managed.c
> > +++ b/drivers/gpu/drm/drm_managed.c
> > @@ -142,6 +142,34 @@ int __drmm_add_action(struct drm_device *dev,
> > }
> > EXPORT_SYMBOL(__drmm_add_action);
> >
> > +void drmm_remove_action(struct drm_device *dev,
> > + drmres_release_t action,
> > + void *data)
> > +{
> > + struct drmres *dr = NULL, *tmp;
> > + unsigned long flags;
> > +
> > + if (!data)
> > + return;
> > +
> > + spin_lock_irqsave(&dev->managed.lock, flags);
> > + list_for_each_entry(tmp, &dev->managed.resources, node.entry) {
> > + if (tmp->node.release == action &&
> > + *(void **)&tmp->data == data) {
> > + dr = tmp;
> > + del_dr(dev, dr);
> > + break;
> > + }
> > + }
> > + spin_unlock_irqrestore(&dev->managed.lock, flags);
> > +
> > + if (WARN_ON(!dr))
> > + return;
> > +
> > + kfree(dr);
> > +}
> > +EXPORT_SYMBOL(drmm_remove_action);
> > +
> > void *drmm_kmalloc(struct drm_device *dev, size_t size, gfp_t gfp)
> > {
> > struct drmres *dr;
> > diff --git a/include/drm/drm_managed.h b/include/drm/drm_managed.h
> > index 89e6fce9f689..5280209dff92 100644
> > --- a/include/drm/drm_managed.h
> > +++ b/include/drm/drm_managed.h
> > @@ -17,6 +17,10 @@ int __must_check __drmm_add_action(struct drm_device *dev,
> > drmres_release_t action,
> > void *data, const char *name);
> >
> > +void drmm_remove_action(struct drm_device *dev,
> > + drmres_release_t action,
> > + void *data);
> > +
> > void drmm_add_final_kfree(struct drm_device *dev, void *parent);
> >
> > void *drmm_kmalloc(struct drm_device *dev, size_t size, gfp_t gfp) __malloc;
> >
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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