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Commit 772269f9 authored by Thomas Hellstrom's avatar Thomas Hellstrom
Browse files

drm/vmwgfx: Fix a circular locking dependency in the fbdev code 



When a user-space process writes directly to the fbdev framebuffer,
we hit a circular locking dependency. Fix this by introducing a local
delayed work callback so that the defio lock can be released before
calling into the modesetting code for a dirty update.

Signed-off-by: default avatarThomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: default avatarSinclair Yeh <syeh@vmware.com>
parent 294947a5

drivers/gpu/drm/vmwgfx/vmwgfx_fb.c

+17 −12
Original line number Diff line number Diff line
@@ -68,8 +68,7 @@ struct vmw_fb_par { 


	struct drm_crtc *crtc;

	struct drm_connector *con;



	bool local_mode;

	struct delayed_work local_work;

};



static int vmw_fb_setcolreg(unsigned regno, unsigned red, unsigned green,
@@ -167,8 +166,10 @@ static int vmw_fb_blank(int blank, struct fb_info *info) 
 * Dirty code

 */



static void vmw_fb_dirty_flush(struct vmw_fb_par *par)

static void vmw_fb_dirty_flush(struct work_struct *work)

{

	struct vmw_fb_par *par = container_of(work, struct vmw_fb_par,

					      local_work.work);

	struct vmw_private *vmw_priv = par->vmw_priv;

	struct fb_info *info = vmw_priv->fb_info;

	unsigned long irq_flags;
@@ -248,7 +249,6 @@ static void vmw_fb_dirty_mark(struct vmw_fb_par *par, 
			      unsigned x1, unsigned y1,

			      unsigned width, unsigned height)

{

	struct fb_info *info = par->vmw_priv->fb_info;

	unsigned long flags;

	unsigned x2 = x1 + width;

	unsigned y2 = y1 + height;
@@ -262,7 +262,8 @@ static void vmw_fb_dirty_mark(struct vmw_fb_par *par, 
		/* if we are active start the dirty work

		 * we share the work with the defio system */

		if (par->dirty.active)

			schedule_delayed_work(&info->deferred_work, VMW_DIRTY_DELAY);

			schedule_delayed_work(&par->local_work,

					      VMW_DIRTY_DELAY);

	} else {

		if (x1 < par->dirty.x1)

			par->dirty.x1 = x1;
@@ -326,9 +327,14 @@ static void vmw_deferred_io(struct fb_info *info, 
		par->dirty.x2 = info->var.xres;

		par->dirty.y2 = y2;

		spin_unlock_irqrestore(&par->dirty.lock, flags);

	}



	vmw_fb_dirty_flush(par);

		/*

		 * Since we've already waited on this work once, try to

		 * execute asap.

		 */

		cancel_delayed_work(&par->local_work);

		schedule_delayed_work(&par->local_work, 0);

	}

};



static struct fb_deferred_io vmw_defio = {
@@ -601,11 +607,7 @@ static int vmw_fb_set_par(struct fb_info *info) 
	/* If there already was stuff dirty we wont

	 * schedule a new work, so lets do it now */



#if (defined(VMWGFX_STANDALONE) && defined(VMWGFX_FB_DEFERRED))

	schedule_delayed_work(&par->def_par.deferred_work, 0);

#else

	schedule_delayed_work(&info->deferred_work, 0);

#endif

	schedule_delayed_work(&par->local_work, 0);



out_unlock:

	if (old_mode)
@@ -662,6 +664,7 @@ int vmw_fb_init(struct vmw_private *vmw_priv) 
	vmw_priv->fb_info = info;

	par = info->par;

	memset(par, 0, sizeof(*par));

	INIT_DELAYED_WORK(&par->local_work, &vmw_fb_dirty_flush);

	par->vmw_priv = vmw_priv;

	par->vmalloc = NULL;

	par->max_width = fb_width;
@@ -784,6 +787,7 @@ int vmw_fb_close(struct vmw_private *vmw_priv) 


	/* ??? order */

	fb_deferred_io_cleanup(info);

	cancel_delayed_work_sync(&par->local_work);

	unregister_framebuffer(info);



	(void) vmw_fb_kms_detach(par, true, true);
@@ -811,6 +815,7 @@ int vmw_fb_off(struct vmw_private *vmw_priv) 
	spin_unlock_irqrestore(&par->dirty.lock, flags);



	flush_delayed_work(&info->deferred_work);

	flush_delayed_work(&par->local_work);



	mutex_lock(&par->bo_mutex);

	(void) vmw_fb_kms_detach(par, true, false);