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
--- drivers/video/fbdev/udlfb.c | 3 ++- include/video/udlfb.h | 1 + 2 files changed, 3 insertions(+), 1 deletion(-)
Index: linux-4.17-rc7/drivers/video/fbdev/udlfb.c =================================================================== --- linux-4.17-rc7.orig/drivers/video/fbdev/udlfb.c 2018-06-03 13:17:33.000000000 +0200 +++ linux-4.17-rc7/drivers/video/fbdev/udlfb.c 2018-06-03 13:17:33.000000000 +0200 @@ -1665,7 +1665,8 @@ static void dlfb_init_framebuffer_work(s 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) { Index: linux-4.17-rc7/include/video/udlfb.h =================================================================== --- linux-4.17-rc7.orig/include/video/udlfb.h 2018-06-03 13:17:33.000000000 +0200 +++ linux-4.17-rc7/include/video/udlfb.h 2018-06-03 13:17:33.000000000 +0200 @@ -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 */