udlfb: make a local copy of fb_ops

The defio subsystem overwrites the method fb_osp->mmap. That method is
stored in module's static data - and that means that if we have multiple
diplaylink adapters, they will over write each other's method.

In order to avoid interference between multiple adapters, we copy the
fb_ops structure to a device-local memory.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

drivers/video/fbdev/udlfb.c

@@ -1665,7 +1665,8 @@ static void dlfb_init_framebuffer_work(struct work_struct *work)
 	dlfb->info = info;
 	info->par = dlfb;
 	info->pseudo_palette = dlfb->pseudo_palette;
-	info->fbops = &dlfb_ops;
+	dlfb->ops = dlfb_ops;
+	info->fbops = &dlfb->ops;
 
 	retval = fb_alloc_cmap(&info->cmap, 256, 0);
 	if (retval < 0) {

include/video/udlfb.h

@@ -51,6 +51,7 @@ struct dlfb_data {
 	int base8;
 	u32 pseudo_palette[256];
 	int blank_mode; /*one of FB_BLANK_ */
+	struct fb_ops ops;
 	/* blit-only rendering path metrics, exposed through sysfs */
 	atomic_t bytes_rendered; /* raw pixel-bytes driver asked to render */
 	atomic_t bytes_identical; /* saved effort with backbuffer comparison */