Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Daniel Vetter <daniel.vetter@ffwll.ch>
To:     DRI Development <dri-devel@lists.freedesktop.org>
Cc:     Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
        linux-fbdev@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Daniel Vetter <daniel.vetter@intel.com>,
        Helge Deller <deller@gmx.de>, Daniel Vetter <daniel@ffwll.ch>,
        Qing Wang <wangqing@vivo.com>, Sam Ravnborg <sam@ravnborg.org>
Subject: [PATCH 07/21] fbdev/sysfs: Fix locking
Date:   Mon, 31 Jan 2022 22:05:38 +0100
Message-Id: <20220131210552.482606-8-daniel.vetter@ffwll.ch>
In-Reply-To: <20220131210552.482606-1-daniel.vetter@ffwll.ch>
References: <20220131210552.482606-1-daniel.vetter@ffwll.ch>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Qing Wang <wangqing@vivo.com>
Cc: Sam Ravnborg <sam@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;
 	console_lock();
+	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);
 	console_unlock();
 	if (err)
 		return err;
-- 
2.33.0