On Wed, Feb 19, 2020 at 5:08 PM Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
>
> Hi Daniel,
>
> On Wed, Feb 19, 2020 at 04:47:55PM +0100, Daniel Vetter wrote:
> > On Wed, Feb 19, 2020 at 2:50 PM Laurent Pinchart wrote:
> > > On Wed, Feb 19, 2020 at 11:20:57AM +0100, Daniel Vetter wrote:
> > > > drm_mode_config_cleanup is idempotent, so no harm in calling this
> > > > twice. This allows us to gradually switch drivers over by removing
> > > > explicit drm_mode_config_cleanup calls.
> > > >
> > > > With this step it's not also possible that (at least for simple
> > > > drivers) automatic resource cleanup can be done correctly without a
> > > > drm_driver->release hook. Therefore allow this now in
> > > > devm_drm_dev_init().
> > > >
> > > > Also with drmm_ explicit drm_driver->release hooks are kinda not the
> > > > best option, so deprecate that hook to discourage future users.
> > > >
> > > > v2: Fixup the example in the kerneldoc too.
> > > >
> > > > Cc: "Noralf Trønnes" <noralf@xxxxxxxxxxx>
> > > > Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
> > > > Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> > > > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> > > > ---
> > > > drivers/gpu/drm/drm_drv.c | 21 +++++----------------
> > > > drivers/gpu/drm/drm_mode_config.c | 12 +++++++++++-
> > > > include/drm/drm_mode_config.h | 2 +-
> > > > 3 files changed, 17 insertions(+), 18 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> > > > index 3cf40864d4a6..428c569aaaf1 100644
> > > > --- a/drivers/gpu/drm/drm_drv.c
> > > > +++ b/drivers/gpu/drm/drm_drv.c
> > > > @@ -267,8 +267,7 @@ void drm_minor_release(struct drm_minor *minor)
> > > > *
> > > > * The following example shows a typical structure of a DRM display driver.
> > > > * The example focus on the probe() function and the other functions that is
> > > > - * almost always present and serves as a demonstration of devm_drm_dev_init()
> > > > - * usage with its accompanying drm_driver->release callback.
> > > > + * almost always present and serves as a demonstration of devm_drm_dev_init().
> > > > *
> > > > * .. code-block:: c
> > > > *
> > > > @@ -278,16 +277,8 @@ void drm_minor_release(struct drm_minor *minor)
> > > > * struct clk *pclk;
> > > > * };
> > > > *
> > > > - * static void driver_drm_release(struct drm_device *drm)
> > > > - * {
> > > > - * struct driver_device *priv = container_of(...);
> > > > - *
> > > > - * drm_mode_config_cleanup(drm);
> > > > - * }
> > > > - *
> > > > * static struct drm_driver driver_drm_driver = {
> > > > * [...]
> > > > - * .release = driver_drm_release,
> > > > * };
> > > > *
> > > > * static int driver_probe(struct platform_device *pdev)
> > > > @@ -312,7 +303,9 @@ void drm_minor_release(struct drm_minor *minor)
> > > > * }
> > > > * drmm_add_final_kfree(drm, priv);
> > > > *
> > > > - * drm_mode_config_init(drm);
> > > > + * ret = drm_mode_config_init(drm);
> > > > + * if (ret)
> > > > + * return ret;
> > > > *
> > > > * priv->userspace_facing = drmm_kzalloc(..., GFP_KERNEL);
> > > > * if (!priv->userspace_facing)
> > > > @@ -710,8 +703,7 @@ static void devm_drm_dev_init_release(void *data)
> > > > * @driver: DRM driver
> > > > *
> > > > * Managed drm_dev_init(). The DRM device initialized with this function is
> > > > - * automatically put on driver detach using drm_dev_put(). You must supply a
> > > > - * &drm_driver.release callback to control the finalization explicitly.
> > > > + * automatically put on driver detach using drm_dev_put().
> > > > *
> > > > * RETURNS:
> > > > * 0 on success, or error code on failure.
> > > > @@ -722,9 +714,6 @@ int devm_drm_dev_init(struct device *parent,
> > > > {
> > > > int ret;
> > > >
> > > > - if (WARN_ON(!driver->release))
> > > > - return -EINVAL;
> > > > -
> > > > ret = drm_dev_init(dev, driver, parent);
> > > > if (ret)
> > > > return ret;
> > > > diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> > > > index 08e6eff6a179..957db1edba0c 100644
> > > > --- a/drivers/gpu/drm/drm_mode_config.c
> > > > +++ b/drivers/gpu/drm/drm_mode_config.c
> > > > @@ -25,6 +25,7 @@
> > > > #include <drm/drm_drv.h>
> > > > #include <drm/drm_encoder.h>
> > > > #include <drm/drm_file.h>
> > > > +#include <drm/drm_managed.h>
> > > > #include <drm/drm_mode_config.h>
> > > > #include <drm/drm_print.h>
> > > > #include <linux/dma-resv.h>
> > > > @@ -373,6 +374,11 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
> > > > return 0;
> > > > }
> > > >
> > > > +static void drm_mode_config_init_release(struct drm_device *dev, void *ptr)
> > > > +{
> > > > + drm_mode_config_cleanup(dev);
> > > > +}
> > > > +
> > > > /**
> > > > * drm_mode_config_init - initialize DRM mode_configuration structure
> > > > * @dev: DRM device
> > > > @@ -384,8 +390,10 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
> > > > * problem, since this should happen single threaded at init time. It is the
> > > > * driver's problem to ensure this guarantee.
> > > > *
> > > > + * Cleanup is automatically handled through registering drm_mode_config_cleanup
> > > > + * with drmm_add_action().
> > > > */
> > > > -void drm_mode_config_init(struct drm_device *dev)
> > > > +int drm_mode_config_init(struct drm_device *dev)
> > > > {
> > > > mutex_init(&dev->mode_config.mutex);
> > > > drm_modeset_lock_init(&dev->mode_config.connection_mutex);
> > > > @@ -443,6 +451,8 @@ void drm_mode_config_init(struct drm_device *dev)
> > > > drm_modeset_acquire_fini(&modeset_ctx);
> > > > dma_resv_fini(&resv);
> > > > }
> > > > +
> > > > + return drmm_add_action(dev, drm_mode_config_init_release, NULL);
> > >
> > > If this fails, shouldn't drm_mode_config_cleanup() be called here ?
> >
> > Maybe for ocd reasons, but not for actually cleaning up anything. It's
> > just a bunch of empty lists that drm_mode_config_cleanup will walk and
> > do nothing about. Not sure I should add that ...
>
> How about the ida init, and the mutex_init() that isn't a no-op when
> lock debugging is enabled ?
Hm right, I'll fix this.
Fun thing is that I've found a pile of missing mutex_destroy and
ida_cleanup() while reviewing all the code I've read. Not sure I've
fixed them all up ...
-Daniel
>
> > > > }
> > > > EXPORT_SYMBOL(drm_mode_config_init);
> > > >
> > > > diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
> > > > index 3bcbe30339f0..160a3e4b51c3 100644
> > > > --- a/include/drm/drm_mode_config.h
> > > > +++ b/include/drm/drm_mode_config.h
> > > > @@ -929,7 +929,7 @@ struct drm_mode_config {
> > > > const struct drm_mode_config_helper_funcs *helper_private;
> > > > };
> > > >
> > > > -void drm_mode_config_init(struct drm_device *dev);
> > > > +int drm_mode_config_init(struct drm_device *dev);
> > > > void drm_mode_config_reset(struct drm_device *dev);
> > > > void drm_mode_config_cleanup(struct drm_device *dev);
> > > >
>
> --
> Regards,
>
> Laurent Pinchart
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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