| From 33cd6ea9c0673517cdb06ad5c915c6f22e9615fc Mon Sep 17 00:00:00 2001 |
| From: Nam Cao <namcao@linutronix.de> |
| Date: Mon, 18 Dec 2023 10:57:31 +0100 |
| Subject: fbdev: flush deferred IO before closing |
| |
| From: Nam Cao <namcao@linutronix.de> |
| |
| 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 <namcao@linutronix.de> |
| Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Signed-off-by: Helge Deller <deller@gmx.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/video/fbdev/core/fb_defio.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/drivers/video/fbdev/core/fb_defio.c |
| +++ b/drivers/video/fbdev/core/fb_defio.c |
| @@ -313,7 +313,7 @@ static void fb_deferred_io_lastclose(str |
| 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) { |
