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Date:   Wed, 5 Sep 2018 17:06:30 +0200
From:   Peter Wu <peter@lekensteyn.nl>
To:     Gerd Hoffmann <kraxel@redhat.com>, David Airlie <airlied@linux.ie>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        virtualization@lists.linux-foundation.org
Subject: Re: [PATCH] bochs: convert to drm_fb_helper_fbdev_setup/teardown
Message-ID: <20180905150630.GA25979@al>
References: <20180905144127.5690-1-peter@lekensteyn.nl>
 <20180905144628.GG4929@phenom.ffwll.local>
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On Wed, Sep 05, 2018 at 04:46:29PM +0200, Daniel Vetter wrote:
> On Wed, Sep 05, 2018 at 04:41:27PM +0200, Peter Wu wrote:
> > Currently unloading bochs_drm (after unbinding the vtconsole) results in
> > a warning about a leaked connector:
> > 
> >     [drm:drm_mode_config_cleanup] *ERROR* connector Virtual-3 leaked!
> > 
> > While investigating a potential fix I noticed that a lot of open-coded
> > functionality is already implemented elsewhere, so start converting it:
> > bochs_fbdev_init -> drm_fb_helper_fbdev_setup: trivial (similar impl).
> > bochs_fbdev_fini -> drm_fb_helper_fbdev_teardown: requires unembedding
> > "struct drm_framebuffer" from "struct bochs_framebuffer".
> > 
> > Unembedding drm_framebuffer is made easy using drm_gem_fbdev_fb_create
> > which can replace bochs_fbdev_destroy and custom routines in bochs_mm.c.
> > For this to work, the GEM object is moved into "drm_framebuffer". After
> > that, "bochs_framebuffer" is no longer needed and therefore removed.
> > 
> > Remove the unused "size" and "initialized" fields from fb, the latter is
> > not necessary as drm_fb_helper_fbdev_teardown can be called even if
> > bochsfb_create fails. This theory was tested by returning early and
> > late (just before drm_gem_fbdev_fb_create). Both scenarios fail
> > gracefully although the latter seems to leak the object from
> > bochsfb_create_object (not a regression).
> > 
> > Guess on the reason for the encoder leak: drm_framebuffer_cleanup was
> > previously used, but did not destroy much. drm_fb_helper_fbdev_teardown
> > is now used and calls drm_framebuffer_remove which does a bit more work.
> > 
> > Tested with 'echo 0 > /sys/class/vtconsole/vtcon1/bind; rmmod bochs_drm'
> > and also with Xorg + fbdev (startx -> xterm). The latter triggered a
> > warning in ttm_bo_vm_open that existed before, see
> > https://lkml.kernel.org/r/1464000533-13140-4-git-send-email-mstaudt@suse.de
> 
> You can probably get rid of this one if you're refactoring even more. The
> generic fb_probe implementation (already merged) plus gem-shmem support
> for it (still in flight) from Noralf should be able to pull that off. That
> gives you the fb_mmap implementation, but with 100% generic code instead
> of a driver specific hack like Max did.

Aside from the warning, I have not observed actual issues. This patch
was prepared on top of v4.18.1 but the new drm_fb_helper_generic_probe
helper is in master (future 4.19). I suppose that it can be done as a
future cleanup. Nice work Noralf on reducing duplication!
.
> > 
> > Signed-off-by: Peter Wu <peter@lekensteyn.nl>
> 
> lgtm. Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> I'll leave merging to Gerd.
> -Daniel

Thanks, I somehow missed a patch. This one does not compile due to
"fb.initialized" still being used in bochs_drv.c. Removal is trivial,
I'll wait for some more feedback and then send a v2 with another patch
prepended.

Kind regards,
Peter

> > ---
> >  drivers/gpu/drm/bochs/bochs.h       | 19 ++-----
> >  drivers/gpu/drm/bochs/bochs_fbdev.c | 79 +++++++----------------------
> >  drivers/gpu/drm/bochs/bochs_kms.c   |  7 +--
> >  drivers/gpu/drm/bochs/bochs_mm.c    | 74 ---------------------------
> >  4 files changed, 22 insertions(+), 157 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/bochs/bochs.h b/drivers/gpu/drm/bochs/bochs.h
> > index 375bf92cd04f..8514a84fbdbe 100644
> > --- a/drivers/gpu/drm/bochs/bochs.h
> > +++ b/drivers/gpu/drm/bochs/bochs.h
> > @@ -51,11 +51,6 @@ enum bochs_types {
> >  	BOCHS_UNKNOWN,
> >  };
> >  
> > -struct bochs_framebuffer {
> > -	struct drm_framebuffer base;
> > -	struct drm_gem_object *obj;
> > -};
> > -
> >  struct bochs_device {
> >  	/* hw */
> >  	void __iomem   *mmio;
> > @@ -88,15 +83,11 @@ struct bochs_device {
> >  
> >  	/* fbdev */
> >  	struct {
> > -		struct bochs_framebuffer gfb;
> > +		struct drm_framebuffer *fb;
> >  		struct drm_fb_helper helper;
> > -		int size;
> > -		bool initialized;
> >  	} fb;
> >  };
> >  
> > -#define to_bochs_framebuffer(x) container_of(x, struct bochs_framebuffer, base)
> > -
> >  struct bochs_bo {
> >  	struct ttm_buffer_object bo;
> >  	struct ttm_placement placement;
> > @@ -148,15 +139,9 @@ int bochs_dumb_create(struct drm_file *file, struct drm_device *dev,
> >  int bochs_dumb_mmap_offset(struct drm_file *file, struct drm_device *dev,
> >  			   uint32_t handle, uint64_t *offset);
> >  
> > -int bochs_framebuffer_init(struct drm_device *dev,
> > -			   struct bochs_framebuffer *gfb,
> > -			   const struct drm_mode_fb_cmd2 *mode_cmd,
> > -			   struct drm_gem_object *obj);
> >  int bochs_bo_pin(struct bochs_bo *bo, u32 pl_flag, u64 *gpu_addr);
> >  int bochs_bo_unpin(struct bochs_bo *bo);
> >  
> > -extern const struct drm_mode_config_funcs bochs_mode_funcs;
> > -
> >  /* bochs_kms.c */
> >  int bochs_kms_init(struct bochs_device *bochs);
> >  void bochs_kms_fini(struct bochs_device *bochs);
> > @@ -164,3 +149,5 @@ void bochs_kms_fini(struct bochs_device *bochs);
> >  /* bochs_fbdev.c */
> >  int bochs_fbdev_init(struct bochs_device *bochs);
> >  void bochs_fbdev_fini(struct bochs_device *bochs);
> > +
> > +extern const struct drm_mode_config_funcs bochs_mode_funcs;
> > diff --git a/drivers/gpu/drm/bochs/bochs_fbdev.c b/drivers/gpu/drm/bochs/bochs_fbdev.c
> > index 14eb8d0d5a00..8f4d6c052f7b 100644
> > --- a/drivers/gpu/drm/bochs/bochs_fbdev.c
> > +++ b/drivers/gpu/drm/bochs/bochs_fbdev.c
> > @@ -6,6 +6,7 @@
> >   */
> >  
> >  #include "bochs.h"
> > +#include <drm/drm_gem_framebuffer_helper.h>
> >  
> >  /* ---------------------------------------------------------------------- */
> >  
> > @@ -13,9 +14,7 @@ static int bochsfb_mmap(struct fb_info *info,
> >  			struct vm_area_struct *vma)
> >  {
> >  	struct drm_fb_helper *fb_helper = info->par;
> > -	struct bochs_device *bochs =
> > -		container_of(fb_helper, struct bochs_device, fb.helper);
> > -	struct bochs_bo *bo = gem_to_bochs_bo(bochs->fb.gfb.obj);
> > +	struct bochs_bo *bo = gem_to_bochs_bo(fb_helper->fb->obj[0]);
> >  
> >  	return ttm_fbdev_mmap(vma, &bo->bo);
> >  }
> > @@ -101,19 +100,20 @@ static int bochsfb_create(struct drm_fb_helper *helper,
> >  
> >  	/* init fb device */
> >  	info = drm_fb_helper_alloc_fbi(helper);
> > -	if (IS_ERR(info))
> > +	if (IS_ERR(info)) {
> > +		DRM_ERROR("Failed to allocate fbi: %ld\n", PTR_ERR(info));
> >  		return PTR_ERR(info);
> > +	}
> >  
> >  	info->par = &bochs->fb.helper;
> >  
> > -	ret = bochs_framebuffer_init(bochs->dev, &bochs->fb.gfb, &mode_cmd, gobj);
> > -	if (ret)
> > -		return ret;
> > -
> > -	bochs->fb.size = size;
> > +	fb = drm_gem_fbdev_fb_create(bochs->dev, sizes, 0, gobj, NULL);
> > +	if (IS_ERR(fb)) {
> > +		DRM_ERROR("Failed to create framebuffer: %ld\n", PTR_ERR(fb));
> > +		return PTR_ERR(fb);
> > +	}
> >  
> >  	/* setup helper */
> > -	fb = &bochs->fb.gfb.base;
> >  	bochs->fb.helper.fb = fb;
> >  
> >  	strcpy(info->fix.id, "bochsdrmfb");
> > @@ -130,27 +130,6 @@ static int bochsfb_create(struct drm_fb_helper *helper,
> >  	drm_vma_offset_remove(&bo->bo.bdev->vma_manager, &bo->bo.vma_node);
> >  	info->fix.smem_start = 0;
> >  	info->fix.smem_len = size;
> > -
> > -	bochs->fb.initialized = true;
> > -	return 0;
> > -}
> > -
> > -static int bochs_fbdev_destroy(struct bochs_device *bochs)
> > -{
> > -	struct bochs_framebuffer *gfb = &bochs->fb.gfb;
> > -
> > -	DRM_DEBUG_DRIVER("\n");
> > -
> > -	drm_fb_helper_unregister_fbi(&bochs->fb.helper);
> > -
> > -	if (gfb->obj) {
> > -		drm_gem_object_unreference_unlocked(gfb->obj);
> > -		gfb->obj = NULL;
> > -	}
> > -
> > -	drm_framebuffer_unregister_private(&gfb->base);
> > -	drm_framebuffer_cleanup(&gfb->base);
> > -
> >  	return 0;
> >  }
> >  
> > @@ -158,41 +137,17 @@ static const struct drm_fb_helper_funcs bochs_fb_helper_funcs = {
> >  	.fb_probe = bochsfb_create,
> >  };
> >  
> > +const struct drm_mode_config_funcs bochs_mode_funcs = {
> > +	.fb_create = drm_gem_fb_create,
> > +};
> > +
> >  int bochs_fbdev_init(struct bochs_device *bochs)
> >  {
> > -	int ret;
> > -
> > -	drm_fb_helper_prepare(bochs->dev, &bochs->fb.helper,
> > -			      &bochs_fb_helper_funcs);
> > -
> > -	ret = drm_fb_helper_init(bochs->dev, &bochs->fb.helper, 1);
> > -	if (ret)
> > -		return ret;
> > -
> > -	ret = drm_fb_helper_single_add_all_connectors(&bochs->fb.helper);
> > -	if (ret)
> > -		goto fini;
> > -
> > -	drm_helper_disable_unused_functions(bochs->dev);
> > -
> > -	ret = drm_fb_helper_initial_config(&bochs->fb.helper, 32);
> > -	if (ret)
> > -		goto fini;
> > -
> > -	return 0;
> > -
> > -fini:
> > -	drm_fb_helper_fini(&bochs->fb.helper);
> > -	return ret;
> > +	return drm_fb_helper_fbdev_setup(bochs->dev, &bochs->fb.helper,
> > +					 &bochs_fb_helper_funcs, 32, 1);
> >  }
> >  
> >  void bochs_fbdev_fini(struct bochs_device *bochs)
> >  {
> > -	if (bochs->fb.initialized)
> > -		bochs_fbdev_destroy(bochs);
> > -
> > -	if (bochs->fb.helper.fbdev)
> > -		drm_fb_helper_fini(&bochs->fb.helper);
> > -
> > -	bochs->fb.initialized = false;
> > +	drm_fb_helper_fbdev_teardown(bochs->dev);
> >  }
> > diff --git a/drivers/gpu/drm/bochs/bochs_kms.c b/drivers/gpu/drm/bochs/bochs_kms.c
> > index 233980a78591..c7e575511d2f 100644
> > --- a/drivers/gpu/drm/bochs/bochs_kms.c
> > +++ b/drivers/gpu/drm/bochs/bochs_kms.c
> > @@ -35,14 +35,12 @@ static int bochs_crtc_mode_set_base(struct drm_crtc *crtc, int x, int y,
> >  {
> >  	struct bochs_device *bochs =
> >  		container_of(crtc, struct bochs_device, crtc);
> > -	struct bochs_framebuffer *bochs_fb;
> >  	struct bochs_bo *bo;
> >  	u64 gpu_addr = 0;
> >  	int ret;
> >  
> >  	if (old_fb) {
> > -		bochs_fb = to_bochs_framebuffer(old_fb);
> > -		bo = gem_to_bochs_bo(bochs_fb->obj);
> > +		bo = gem_to_bochs_bo(old_fb->obj[0]);
> >  		ret = ttm_bo_reserve(&bo->bo, true, false, NULL);
> >  		if (ret) {
> >  			DRM_ERROR("failed to reserve old_fb bo\n");
> > @@ -55,8 +53,7 @@ static int bochs_crtc_mode_set_base(struct drm_crtc *crtc, int x, int y,
> >  	if (WARN_ON(crtc->primary->fb == NULL))
> >  		return -EINVAL;
> >  
> > -	bochs_fb = to_bochs_framebuffer(crtc->primary->fb);
> > -	bo = gem_to_bochs_bo(bochs_fb->obj);
> > +	bo = gem_to_bochs_bo(crtc->primary->fb->obj[0]);
> >  	ret = ttm_bo_reserve(&bo->bo, true, false, NULL);
> >  	if (ret)
> >  		return ret;
> > diff --git a/drivers/gpu/drm/bochs/bochs_mm.c b/drivers/gpu/drm/bochs/bochs_mm.c
> > index 39cd08416773..cdbc3ca3ec51 100644
> > --- a/drivers/gpu/drm/bochs/bochs_mm.c
> > +++ b/drivers/gpu/drm/bochs/bochs_mm.c
> > @@ -457,77 +457,3 @@ int bochs_dumb_mmap_offset(struct drm_file *file, struct drm_device *dev,
> >  	drm_gem_object_unreference_unlocked(obj);
> >  	return 0;
> >  }
> > -
> > -/* ---------------------------------------------------------------------- */
> > -
> > -static void bochs_user_framebuffer_destroy(struct drm_framebuffer *fb)
> > -{
> > -	struct bochs_framebuffer *bochs_fb = to_bochs_framebuffer(fb);
> > -
> > -	drm_gem_object_unreference_unlocked(bochs_fb->obj);
> > -	drm_framebuffer_cleanup(fb);
> > -	kfree(fb);
> > -}
> > -
> > -static const struct drm_framebuffer_funcs bochs_fb_funcs = {
> > -	.destroy = bochs_user_framebuffer_destroy,
> > -};
> > -
> > -int bochs_framebuffer_init(struct drm_device *dev,
> > -			   struct bochs_framebuffer *gfb,
> > -			   const struct drm_mode_fb_cmd2 *mode_cmd,
> > -			   struct drm_gem_object *obj)
> > -{
> > -	int ret;
> > -
> > -	drm_helper_mode_fill_fb_struct(dev, &gfb->base, mode_cmd);
> > -	gfb->obj = obj;
> > -	ret = drm_framebuffer_init(dev, &gfb->base, &bochs_fb_funcs);
> > -	if (ret) {
> > -		DRM_ERROR("drm_framebuffer_init failed: %d\n", ret);
> > -		return ret;
> > -	}
> > -	return 0;
> > -}
> > -
> > -static struct drm_framebuffer *
> > -bochs_user_framebuffer_create(struct drm_device *dev,
> > -			      struct drm_file *filp,
> > -			      const struct drm_mode_fb_cmd2 *mode_cmd)
> > -{
> > -	struct drm_gem_object *obj;
> > -	struct bochs_framebuffer *bochs_fb;
> > -	int ret;
> > -
> > -	DRM_DEBUG_DRIVER("%dx%d, format %c%c%c%c\n",
> > -	       mode_cmd->width, mode_cmd->height,
> > -	       (mode_cmd->pixel_format)       & 0xff,
> > -	       (mode_cmd->pixel_format >> 8)  & 0xff,
> > -	       (mode_cmd->pixel_format >> 16) & 0xff,
> > -	       (mode_cmd->pixel_format >> 24) & 0xff);
> > -
> > -	if (mode_cmd->pixel_format != DRM_FORMAT_XRGB8888)
> > -		return ERR_PTR(-ENOENT);
> > -
> > -	obj = drm_gem_object_lookup(filp, mode_cmd->handles[0]);
> > -	if (obj == NULL)
> > -		return ERR_PTR(-ENOENT);
> > -
> > -	bochs_fb = kzalloc(sizeof(*bochs_fb), GFP_KERNEL);
> > -	if (!bochs_fb) {
> > -		drm_gem_object_unreference_unlocked(obj);
> > -		return ERR_PTR(-ENOMEM);
> > -	}
> > -
> > -	ret = bochs_framebuffer_init(dev, bochs_fb, mode_cmd, obj);
> > -	if (ret) {
> > -		drm_gem_object_unreference_unlocked(obj);
> > -		kfree(bochs_fb);
> > -		return ERR_PTR(ret);
> > -	}
> > -	return &bochs_fb->base;
> > -}
> > -
> > -const struct drm_mode_config_funcs bochs_mode_funcs = {
> > -	.fb_create = bochs_user_framebuffer_create,
> > -};
> > -- 
> > 2.18.0
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Kind regards,
Peter Wu
https://lekensteyn.nl