[Intel-gfx] [PATCH v2 05/19] fbdev/sysfs: Fix locking

Daniel Vetter daniel.vetter at ffwll.ch
Tue Feb 8 21:08:10 UTC 2022

fb_set_var requires we hold the fb_info lock. Or at least this now
matches what the ioctl does ...

Note that ps3fb and sh_mobile_lcdcfb are busted in different ways here,
but I will not fix them up.

Also in practice this isn't a big deal, because really variable fbdev
state is actually protected by console_lock (because fbcon just
doesn't bother with lock_fb_info() at all), and lock_fb_info
protecting anything is really just a neat lie. But that's a much
bigger fish to fry.

Acked-by: Sam Ravnborg <sam at ravnborg.org>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Cc: Helge Deller <deller at gmx.de>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: Qing Wang <wangqing at vivo.com>
Cc: Sam Ravnborg <sam at ravnborg.org>
 drivers/video/fbdev/core/fbsysfs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c
index 26892940c213..8c1ee9ecec3d 100644
--- a/drivers/video/fbdev/core/fbsysfs.c
+++ b/drivers/video/fbdev/core/fbsysfs.c
@@ -91,9 +91,11 @@ static int activate(struct fb_info *fb_info, struct fb_var_screeninfo *var)
 	var->activate |= FB_ACTIVATE_FORCE;
+	lock_fb_info(fb_info);
 	err = fb_set_var(fb_info, var);
 	if (!err)
 		fbcon_update_vcs(fb_info, var->activate & FB_ACTIVATE_ALL);
+	unlock_fb_info(fb_info);
 	if (err)
 		return err;

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