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Commit 25981de5 authored by Michael Hanselmann's avatar Michael Hanselmann Committed by Linus Torvalds
Browse files

[PATCH] backlight: fix oops in __mutex_lock_slowpath during head /sys/class/graphics/fb0/* 



Seems like not all drivers use the framebuffer_alloc() function and won't
have an initialized mutex.  But those don't have a backlight, anyway.

Signed-off-by: default avatarMichael Hanselmann <linux-kernel@hansmi.ch>
Cc: Olaf Hering <olaf@aepfle.de>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Daniel R Thompson <daniel.thompson@st.com>
Cc: Jon Smirl <jonsmirl@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f3ef9ead

drivers/video/fbsysfs.c

+12 −0
Original line number Diff line number Diff line
@@ -397,6 +397,12 @@ static ssize_t store_bl_curve(struct class_device *class_device, 
	u8 tmp_curve[FB_BACKLIGHT_LEVELS];

	unsigned int i;



	/* Some drivers don't use framebuffer_alloc(), but those also

	 * don't have backlights.

	 */

	if (!fb_info || !fb_info->bl_dev)

		return -ENODEV;



	if (count != (FB_BACKLIGHT_LEVELS / 8 * 24))

		return -EINVAL;
@@ -430,6 +436,12 @@ static ssize_t show_bl_curve(struct class_device *class_device, char *buf) 
	ssize_t len = 0;

	unsigned int i;



	/* Some drivers don't use framebuffer_alloc(), but those also

	 * don't have backlights.

	 */

	if (!fb_info || !fb_info->bl_dev)

		return -ENODEV;



	mutex_lock(&fb_info->bl_mutex);

	for (i = 0; i < FB_BACKLIGHT_LEVELS; i += 8)

		len += snprintf(&buf[len], PAGE_SIZE,