Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Thomas Zimmermann <tzimmermann@suse.de>
To:     daniel@ffwll.ch, javierm@redhat.com, sam@ravnborg.org,
        deller@gmx.de, geert+renesas@glider.be, lee@kernel.org,
        daniel.thompson@linaro.org, jingoohan1@gmail.com,
        dan.carpenter@linaro.org, michael.j.ruhl@intel.com
Cc:     linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-sh@vger.kernel.org, linux-omap@vger.kernel.org,
        linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Steve Glendinning <steve.glendinning@shawell.net>
Subject: [PATCH v2 30/38] fbdev/smscufx: Detect registered fb_info from refcount
Date:   Mon, 12 Jun 2023 16:08:08 +0200
Message-ID: <20230612141352.29939-31-tzimmermann@suse.de>
In-Reply-To: <20230612141352.29939-1-tzimmermann@suse.de>
References: <20230612141352.29939-1-tzimmermann@suse.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Detect registered instances of fb_info by reading the reference
counter from struct fb_info.read. Avoids looking at the dev field
and prepares fbdev for making struct fb_info.dev optional.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Steve Glendinning <steve.glendinning@shawell.net>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
---
 drivers/video/fbdev/smscufx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/smscufx.c b/drivers/video/fbdev/smscufx.c
index 17cec62cc65db..adb2b1fe8383c 100644
--- a/drivers/video/fbdev/smscufx.c
+++ b/drivers/video/fbdev/smscufx.c
@@ -1496,7 +1496,7 @@ static int ufx_setup_modes(struct ufx_data *dev, struct fb_info *info,
 	u8 *edid;
 	int i, result = 0, tries = 3;
 
-	if (info->dev) /* only use mutex if info has been registered */
+	if (refcount_read(&info->count)) /* only use mutex if info has been registered */
 		mutex_lock(&info->lock);
 
 	edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
@@ -1610,7 +1610,7 @@ static int ufx_setup_modes(struct ufx_data *dev, struct fb_info *info,
 	if (edid && (dev->edid != edid))
 		kfree(edid);
 
-	if (info->dev)
+	if (refcount_read(&info->count))
 		mutex_unlock(&info->lock);
 
 	return result;
-- 
2.41.0