From 81f444f22816a82ada2cc787a2845cffc8c584a6 Mon Sep 17 00:00:00 2001 From: Nam Cao Date: Mon, 18 Dec 2023 10:57:31 +0100 Subject: [PATCH] fbdev: flush deferred IO before closing commit 33cd6ea9c0673517cdb06ad5c915c6f22e9615fc upstream. When framebuffer gets closed, the queued deferred IO gets cancelled. This can cause some last display data to vanish. This is problematic for users who send a still image to the framebuffer, then close the file: the image may never appear. To ensure none of display data get lost, flush the queued deferred IO first before closing. Another possible solution is to delete the cancel_delayed_work_sync() instead. The difference is that the display may appear some time after closing. However, the clearing of page mapping after this needs to be removed too, because the page mapping is used by the deferred work. It is not completely obvious whether it is okay to not clear the page mapping. For a patch intended for stable trees, go with the simple and obvious solution. Fixes: 60b59beafba8 ("fbdev: mm: Deferred IO support") Cc: stable@vger.kernel.org Signed-off-by: Nam Cao Reviewed-by: Sebastian Andrzej Siewior Signed-off-by: Helge Deller Signed-off-by: Greg Kroah-Hartman --- drivers/video/fbdev/core/fb_defio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c index ff38c5da86fa..49883c8012e6 100644 --- a/drivers/video/fbdev/core/fb_defio.c +++ b/drivers/video/fbdev/core/fb_defio.c @@ -317,7 +317,7 @@ static void fb_deferred_io_lastclose(struct fb_info *info) struct page *page; int i; - cancel_delayed_work_sync(&info->deferred_work); + flush_delayed_work(&info->deferred_work); /* clear out the mapping that we setup */ for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {