Nice done. Thanks for finding the bug. I write most part of ideapad-laptop.c though the maintainer is still Matthew. I think the patch attached below is much simple and we can avoid unnecessary read_ec_data if blightdev is not set. Since you are the one who find the bug and have the first patch, I would like to keep you as author and your sign off. Of course I need your agree. (Hoping I do not break the sign-off rule) Please review the patch below and reply if you agree with this or disagree. Hi Matthew, When acpi_backlight=video, priv->blightdev will be NULL and use it without checking will cause kernel oops. I suggest we shall have the fix in v3.1 cycle. ====== 8< ====== >From 8bd37cd5da31abaca4b906bc84eb45a0834678ea Mon Sep 17 00:00:00 2001 From: Rene Bolldorf <xsecute@xxxxxxxxxxxxxx> Date: Wed, 24 Aug 2011 09:56:24 +0800 Subject: [PATCH] ideapad: Check if acpi already handle backlight power in 'ideapad_backlight_notify_power' to avoid a page fault This patch avoid a page fault in the ideapad-laptop extras when turning the backlight power on or off. Signed-off-by: Rene Bolldorf <xsecute@xxxxxxxxxxxxxx> Signed-off-by: Ike Panhc <ike.pan@xxxxxxxxxxxxx> --- drivers/platform/x86/ideapad-laptop.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/drivers/platform/x86/ideapad-laptop.c b/drivers/platform/x86/ideapad-laptop.c index 0c59541..0d94eec 100644 --- a/drivers/platform/x86/ideapad-laptop.c +++ b/drivers/platform/x86/ideapad-laptop.c @@ -493,6 +493,8 @@ static void ideapad_backlight_notify_power(struct ideapad_private *priv) unsigned long power; struct backlight_device *blightdev = priv->blightdev; + if (!blightdev) + return; if (read_ec_data(ideapad_handle, 0x18, &power)) return; blightdev->props.power = power ? FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN; -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
