diff options
| author | Takashi Iwai <tiwai@suse.de> | 2023-03-08 11:50:12 +0100 |
|---|---|---|
| committer | Thomas Zimmermann <tzimmermann@suse.de> | 2023-03-10 14:13:02 +0100 |
| commit | fe9ae05cfbe587dda724fcf537c00bc2f287da62 (patch) | |
| tree | 9517174524bf333a640f088ef15d6a5ef6ce3474 /include | |
| parent | drm/ttm: Fix a NULL pointer dereference (diff) | |
| download | linux-fe9ae05cfbe587dda724fcf537c00bc2f287da62.tar.xz linux-fe9ae05cfbe587dda724fcf537c00bc2f287da62.zip | |
fbdev: Fix incorrect page mapping clearance at fb_deferred_io_release()
The recent fix for the deferred I/O by the commit
3efc61d95259 ("fbdev: Fix invalid page access after closing deferred I/O devices")
caused a regression when the same fb device is opened/closed while
it's being used. It resulted in a frozen screen even if something
is redrawn there after the close. The breakage is because the patch
was made under a wrong assumption of a single open; in the current
code, fb_deferred_io_release() cleans up the page mapping of the
pageref list and it calls cancel_delayed_work_sync() unconditionally,
where both are no correct behavior for multiple opens.
This patch adds a refcount for the opens of the device, and applies
the cleanup only when all files get closed.
As both fb_deferred_io_open() and _close() are called always in the
fb_info lock (mutex), it's safe to use the normal int for the
refcounting.
Also, a useless BUG_ON() is dropped.
Fixes: 3efc61d95259 ("fbdev: Fix invalid page access after closing deferred I/O devices")
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230308105012.1845-1-tiwai@suse.de
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/fb.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/fb.h b/include/linux/fb.h index 73eb1f85ea8e..05e40fcc7696 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -212,6 +212,7 @@ struct fb_deferred_io { /* delay between mkwrite and deferred handler */ unsigned long delay; bool sort_pagereflist; /* sort pagelist by offset */ + int open_count; /* number of opened files; protected by fb_info lock */ struct mutex lock; /* mutex that protects the pageref list */ struct list_head pagereflist; /* list of pagerefs for touched pages */ /* callback */ |