| Message ID | 1387570873-20246-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index e1f6860..7decd90 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -460,11 +460,13 @@ EXPORT_SYMBOL_GPL(cpuidle_register_device); */ void cpuidle_unregister_device(struct cpuidle_device *dev) { - struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); + struct cpuidle_driver *drv; - if (dev->registered == 0) + if (!dev || dev->registered == 0) return; + drv = cpuidle_get_cpu_driver(dev); + cpuidle_pause_and_lock(); cpuidle_disable_device(dev);
This is a note to let you know that I have just added a patch titled cpuidle: Check for dev before deregistering it. to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.15. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From ad78bf26dcd6daf638286222320010d241fdcaa5 Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Date: Tue, 3 Dec 2013 10:59:58 -0500 Subject: cpuidle: Check for dev before deregistering it. commit 813e8e3d6aaa0b511126cce15c16a931afffe768 upstream. If not, we could end up in the unfortunate situation where we dereference a NULL pointer b/c we have cpuidle disabled. This is the case when booting under Xen (which uses the ACPI P/C states but disables the CPU idle driver) - and can be easily reproduced when booting with cpuidle.off=1. BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff8156db4a>] cpuidle_unregister_device+0x2a/0x90 .. snip.. Call Trace: [<ffffffff813b15b4>] acpi_processor_power_exit+0x3c/0x5c [<ffffffff813af0a9>] acpi_processor_stop+0x61/0xb6 [<ffffffff814215bf>] __device_release_driver+0fffff81421653>] device_release_driver+0x23/0x30 [<ffffffff81420ed8>] bus_remove_device+0x108/0x180 [<ffffffff8141d9d9>] device_del+0x129/0x1c0 [<ffffffff813cb4b0>] ? unregister_xenbus_watch+0x1f0/0x1f0 [<ffffffff8141da8e>] device_unregister+0x1e/0x60 [<ffffffff814243e9>] unregister_cpu+0x39/0x60 [<ffffffff81019e03>] arch_unregister_cpu+0x23/0x30 [<ffffffff813c3c51>] handle_vcpu_hotplug_event+0xc1/0xe0 [<ffffffff813cb4f5>] xenwatch_thread+0x45/0x120 [<ffffffff810af010>] ? abort_exclusive_wait+0xb0/0xb0 [<ffffffff8108ec42>] kthread+0xd2/0xf0 [<ffffffff8108eb70>] ? kthread_create_on_node+0x180/0x180 [<ffffffff816ce17c>] ret_from_fork+0x7c/0xb0 [<ffffffff8108eb70>] ? kthread_create_on_node+0x180/0x180 This problem also appears in 3.12 and could be a candidate for backport. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> [ kamal: backport to 3.8 ] Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/cpuidle/cpuidle.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) -- 1.8.3.2