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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: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
This commit is contained in:
Thomas Hellstrom 2015-08-18 09:07:38 -07:00
parent 294947a5c7
commit 772269f970
1 changed files with 17 additions and 12 deletions
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29
drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
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@ -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);