Re: [PATCH 07/11] drm/tinydrm/repaper: Use devm_drm_dev_*()

[Sam Ravnborg <sam@ravnborg.org>]

On Sun, Jan 20, 2019 at 11:22:36PM +0100, Sam Ravnborg wrote:
> Hi Noralf.
> 
> On Sun, Jan 20, 2019 at 12:43:14PM +0100, Noralf Trønnes wrote:
> > Use devm_drm_dev_init(), devm_drm_dev_register_with_fbdev() and drop
> > using tinydrm_device.
> > 
> > Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> > ---
> >  drivers/gpu/drm/tinydrm/repaper.c | 63 ++++++++++++++++++++-----------
> >  1 file changed, 40 insertions(+), 23 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/tinydrm/repaper.c b/drivers/gpu/drm/tinydrm/repaper.c
> > index 3141241ca8f0..4c8205565668 100644
> > --- a/drivers/gpu/drm/tinydrm/repaper.c
> > +++ b/drivers/gpu/drm/tinydrm/repaper.c
> > @@ -34,7 +34,7 @@
> >  #include <drm/drm_gem_framebuffer_helper.h>
> >  #include <drm/drm_rect.h>
> >  #include <drm/drm_vblank.h>
> > -#include <drm/tinydrm/tinydrm.h>
> > +#include <drm/drm_simple_kms_helper.h>
> >  #include <drm/tinydrm/tinydrm-helpers.h>
> >  
> >  #define REPAPER_RID_G2_COG_ID	0x12
> > @@ -60,7 +60,8 @@ enum repaper_epd_border_byte {
> >  };
> >  
> >  struct repaper_epd {
> > -	struct tinydrm_device tinydrm;
> > +	struct drm_device base;
> > +	struct drm_simple_display_pipe pipe;
> >  	struct spi_device *spi;
> >  
> >  	struct gpio_desc *panel_on;
> > @@ -89,10 +90,9 @@ struct repaper_epd {
> >  	bool partial;
> >  };
> >  
> > -static inline struct repaper_epd *
> > -epd_from_tinydrm(struct tinydrm_device *tdev)
> > +static inline struct repaper_epd *drm_to_epd(struct drm_device *drm)
> >  {
> > -	return container_of(tdev, struct repaper_epd, tinydrm);
> > +	return container_of(drm, struct repaper_epd, base);
> >  }
> >  
> >  static int repaper_spi_transfer(struct spi_device *spi, u8 header,
> > @@ -530,8 +530,7 @@ static int repaper_fb_dirty(struct drm_framebuffer *fb)
> >  {
> >  	struct drm_gem_cma_object *cma_obj = drm_fb_cma_get_gem_obj(fb, 0);
> >  	struct dma_buf_attachment *import_attach = cma_obj->base.import_attach;
> > -	struct tinydrm_device *tdev = fb->dev->dev_private;
> > -	struct repaper_epd *epd = epd_from_tinydrm(tdev);
> > +	struct repaper_epd *epd = drm_to_epd(fb->dev);
> >  	struct drm_rect clip;
> >  	u8 *buf = NULL;
> >  	int ret = 0;
> > @@ -646,8 +645,7 @@ static void repaper_pipe_enable(struct drm_simple_display_pipe *pipe,
> >  				struct drm_crtc_state *crtc_state,
> >  				struct drm_plane_state *plane_state)
> >  {
> > -	struct tinydrm_device *tdev = pipe_to_tinydrm(pipe);
> > -	struct repaper_epd *epd = epd_from_tinydrm(tdev);
> > +	struct repaper_epd *epd = drm_to_epd(pipe->crtc.dev);
> >  	struct spi_device *spi = epd->spi;
> >  	struct device *dev = &spi->dev;
> >  	bool dc_ok = false;
> > @@ -781,8 +779,7 @@ static void repaper_pipe_enable(struct drm_simple_display_pipe *pipe,
> >  
> >  static void repaper_pipe_disable(struct drm_simple_display_pipe *pipe)
> >  {
> > -	struct tinydrm_device *tdev = pipe_to_tinydrm(pipe);
> > -	struct repaper_epd *epd = epd_from_tinydrm(tdev);
> > +	struct repaper_epd *epd = drm_to_epd(pipe->crtc.dev);
> >  	struct spi_device *spi = epd->spi;
> >  	unsigned int line;
> >  
> > @@ -856,6 +853,23 @@ static const struct drm_simple_display_pipe_funcs repaper_pipe_funcs = {
> >  	.prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
> >  };
> >  
> > +static const struct drm_mode_config_funcs repaper_mode_config_funcs = {
> > +	.fb_create = drm_gem_fb_create_with_dirty,
> > +	.atomic_check = drm_atomic_helper_check,
> > +	.atomic_commit = drm_atomic_helper_commit,
> > +};
> > +
> > +static void repaper_release(struct drm_device *drm)
> > +{
> > +	struct repaper_epd *epd = drm_to_epd(drm);
> > +
> > +	DRM_DEBUG_DRIVER("\n");
> > +
> > +	drm_mode_config_cleanup(drm);
> > +	drm_dev_fini(drm);
> > +	kfree(epd);
> > +}
> > +
> >  static const uint32_t repaper_formats[] = {
> >  	DRM_FORMAT_XRGB8888,
> >  };
> > @@ -894,6 +908,7 @@ static struct drm_driver repaper_driver = {
> >  	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_PRIME |
> >  				  DRIVER_ATOMIC,
> >  	.fops			= &repaper_fops,
> > +	.release		= repaper_release,
> >  	DRM_GEM_CMA_VMAP_DRIVER_OPS,
> >  	.name			= "repaper",
> >  	.desc			= "Pervasive Displays RePaper e-ink panels",
> > @@ -927,7 +942,6 @@ static int repaper_probe(struct spi_device *spi)
> >  	const struct of_device_id *match;
> >  	struct drm_connector *connector;
> >  	struct device *dev = &spi->dev;
> > -	struct tinydrm_device *tdev;
> >  	enum repaper_model model;
> >  	const char *thermal_zone;
> >  	struct repaper_epd *epd;
> > @@ -952,10 +966,20 @@ static int repaper_probe(struct spi_device *spi)
> >  		}
> >  	}
> >  
> > -	epd = devm_kzalloc(dev, sizeof(*epd), GFP_KERNEL);
> > +	epd = kzalloc(sizeof(*epd), GFP_KERNEL);
> >  	if (!epd)
> >  		return -ENOMEM;
> >  
> > +	drm = &epd->base;
> > +	ret = devm_drm_dev_init(dev, drm, &repaper_driver);
> > +	if (ret) {
> > +		kfree(epd);
> > +		return ret;
> > +	}
> Here you go to the trouble and free epd on error.
> 
> > +
> > +	drm_mode_config_init(drm);
> > +	drm->mode_config.funcs = &repaper_mode_config_funcs;
> > +
> >  	epd->spi = spi;
> >  
> >  	epd->panel_on = devm_gpiod_get(dev, "panel-on", GPIOD_OUT_LOW);
> > @@ -1066,32 +1090,25 @@ static int repaper_probe(struct spi_device *spi)
> >  	if (!epd->current_frame)
> >  		return -ENOMEM;
> >  
> > -	tdev = &epd->tinydrm;
> > -
> > -	ret = devm_tinydrm_init(dev, tdev, &repaper_driver);
> > -	if (ret)
> > -		return ret;
> > -
> > -	drm = tdev->drm;
> >  
> >  	connector = drm_simple_connector_create(drm, DRM_MODE_CONNECTOR_VIRTUAL, mode, 0);
> >  	if (IS_ERR(connector))
> >  		return PTR_ERR(connector);
> >  
> > -	ret = drm_simple_display_pipe_init(drm, &tdev->pipe, &repaper_pipe_funcs,
> > +	ret = drm_simple_display_pipe_init(drm, &epd->pipe, &repaper_pipe_funcs,
> >  					   repaper_formats, ARRAY_SIZE(repaper_formats),
> >  					   NULL, connector);
> >  	if (ret)
> >  		return ret;
> But later in the same function epd is not freed.
> Looks like a leak?
> Nothing new if this is correct but just spotted it.

The part with "nothing new" I take back. This code converts
devm_kzalloc() to the unmanaged variant.
So the leak is new - and also present in
drivers in next patch (if there is a leak).

Why is the conversion to an unmanaged variant of kzalloc() required?

	Sam
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