Messages in this thread Patch in this message | | | Date | Wed, 28 Jan 2009 18:02:51 +0000 | From | Darren Salt <> | Subject | [PATCH] Oops when changing backlight brightness during eeepc-laptop init |
| |
I got the following oops while changing the backlight brightness during startup. When it happens, it prevents use of the hotkeys, Fn-Fx, and the lid button.
It's a clear use-before-init, as I verified by testing with an appropriately-placed "else printk".
BUG: unable to handle kernel NULL pointer dereference at 00000000 *pde = 00000000 Oops: 0002 [#1] PREEMPT SMP Pid: 160, comm: kacpi_notify Not tainted (2.6.28.1-eee901 #4) 901 EIP: 0060:[<c0264e68>] [<c0264e68>] eeepc_hotk_notify+26/da EFLAGS: 00010246 CPU: 1 Using defaults from ksymoops -t elf32-i386 -a i386 EAX: 00000009 EBX: 00000000 ECX: 00000009 EDX: f70dbf64 ESI: 00000029 EDI: f7335188 EBP: c02112c9 ESP: f70dbf80 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 f70731e0 f73acd50 c02164ac f7335180 f70aa040 c02112e6 f733518c c012b62f f70aa044 f70aa040 c012bdba f70aa04c 00000000 c012be6e 00000000 f70bdf80 c012e198 f70dbfc4 f70dbfc4 f70aa040 c012bdba 00000000 c012e0c9 c012e091 Call Trace: [<c02164ac>] ? acpi_ev_notify_dispatch+4c/55 [<c02112e6>] ? acpi_os_execute_deferred+1d/25 [<c012b62f>] ? run_workqueue+71/f1 [<c012bdba>] ? worker_thread+0/bf [<c012be6e>] ? worker_thread+b4/bf [<c012e198>] ? autoremove_wake_function+0/2b [<c012bdba>] ? worker_thread+0/bf [<c012e0c9>] ? kthread+38/5f [<c012e091>] ? kthread+0/5f [<c0103abf>] ? kernel_thread_helper+7/10 Code: 00 00 00 00 c3 83 3d 60 5c 50 c0 00 56 89 d6 53 0f 84 c4 00 00 00 8d 42 e0 83 f8 0f 77 0f 8b 1d 68 5c 50 c0 89 d8 e8 a9 fa ff ff <89> 03 8b 1d 60 5c 50 c0 89 f2 83 e2 7f 0f b7 4c 53 10 8d 41 01
Signed-off-by: Darren Salt <linux@youmustbejoking.demon.co.uk>
(The patch is against 2.6.28.1. It's also needed for 2.6.29, in which I see that the driver is now in drivers/platform/x86. Hardware is a 901 with BIOS 1808.)
--- a/drivers/misc/eeepc-laptop.c +++ b/drivers/misc/eeepc-laptop.c @@ -510,7 +510,8 @@ static void notify_brn(void) { struct backlight_device *bd = eeepc_backlight_device; - bd->props.brightness = read_brightness(bd); + if (bd) + bd->props.brightness = read_brightness(bd); } static void eeepc_hotk_notify(acpi_handle handle, u32 event, void *data) -- | Darren Salt | linux or ds at | nr. Ashington, | Toon | RISC OS, Linux | youmustbejoking,demon,co,uk | Northumberland | Army | + Buy less and make it last longer. INDUSTRY CAUSES GLOBAL WARMING.
Never be first. Never be last. Never volunteer for anything.
| |