Re: [PATCH] drm/i915/lvds: Move acpi lid notification registration to registration phase

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 18 May 2018, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> Delay registering ourselves with the acpi lid notification mechansim
> until we are registering the connectors after initialisation is
> complete. This prevents a possibilty of trying to handle the lid
> notification before we are ready with the danger of chasing
> uninitialised function pointers.
>
>  BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
>  IP:           (null)
>  PGD 0 P4D 0
>  Oops: 0010 [#1] PREEMPT SMP PTI
>  Modules linked in: arc4(+) iwldvm(+) i915(+) mac80211 i2c_algo_bit coretemp mei_wdt iwlwifi drm_kms_helper kvm_intel wmi_bmof iTCO_wdt iTCO_vendor_support kvm snd_hda_codec_conexant snd_hda_codec_generic drm psmouse cfg80211 irqbypass input_leds pcspkr i2c_i801 snd_hda_intel snd_hda_codec thinkpad_acpi snd_hda_core mei_me lpc_ich snd_hwdep e1000e wmi nvram snd_pcm mei snd_timer shpchp ptp pps_core rfkill syscopyarea snd intel_agp sysfillrect intel_gtt soundcore sysimgblt battery led_class fb_sys_fops ac rtc_cmos agpgart evdev mac_hid acpi_cpufreq ip_tables x_tables ext4 crc32c_generic crc16 mbcache jbd2 fscrypto crypto_simd glue_helper cryptd aes_x86_64 xts algif_skcipher af_alg dm_crypt dm_mod sd_mod uas usb_storage serio_raw atkbd libps2 ahci libahci uhci_hcd libata scsi_mod ehci_pci
>   ehci_hcd usbcore usb_common i8042 serio
>  CPU: 1 PID: 378 Comm: systemd-logind Not tainted 4.16.8-1-ARCH #1
>  Hardware name: LENOVO 7454CTO/7454CTO, BIOS 6DET72WW (3.22 ) 10/25/2012
>  RIP: 0010:          (null)
>  RSP: 0018:ffffaf4580c33a18 EFLAGS: 00010287
>  RAX: 0000000000000000 RBX: ffff947533558000 RCX: 000000000000003e
>  RDX: ffffffffc0aa80c0 RSI: ffffaf4580c33a3c RDI: ffff947534e4c000
>  RBP: ffff947533558338 R08: ffff947534598930 R09: ffffffffc0a928b1
>  R10: ffffd8f181d5fd40 R11: 0000000000000000 R12: ffffffffc0a928b1
>  R13: ffff947533558368 R14: ffffffffc0a928a9 R15: ffff947534e4c000
>  FS:  00007f3dc4ddb940(0000) GS:ffff947539280000(0000) knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: 0000000000000000 CR3: 000000006e214000 CR4: 00000000000406e0
>  Call Trace:
>   ?  intel_modeset_setup_hw_state+0x385/0xf60 [i915]
>   ? __intel_display_resume+0x1e/0xc0 [i915]
>   ? intel_display_resume+0xcc/0x120 [i915]
>   ? intel_lid_notify+0xbc/0xc0 [i915]
>   ? notifier_call_chain+0x47/0x70
>   ? blocking_notifier_call_chain+0x3e/0x60
>   ? acpi_lid_notify_state+0x8f/0x1d0
>   ? acpi_lid_update_state+0x49/0x70
>   ? acpi_lid_input_open+0x60/0x90
>   ? input_open_device+0x5d/0xa0
>   ? evdev_open+0x1ba/0x1e0 [evdev]
>   ? chrdev_open+0xa3/0x1b0
>   ? cdev_put.part.0+0x20/0x20
>   ? do_dentry_open+0x14c/0x300
>   ? path_openat+0x30c/0x1240
>   ? current_time+0x16/0x60
>   ? do_filp_open+0x93/0x100
>   ? __check_object_size+0xfb/0x180
>   ? do_sys_open+0x186/0x210
>   ? do_syscall_64+0x74/0x190
>   ?  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
>  Code:  Bad RIP value.
>  RIP:           (null) RSP: ffffaf4580c33a18
>  CR2: 0000000000000000
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106559
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>

Cc: stable@vger.kernel.org ?
Fixes: ?
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/intel_lvds.c | 43 +++++++++++++++++++++++--------
>  1 file changed, 32 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
> index 8691c86f579c..a844d48e6731 100644
> --- a/drivers/gpu/drm/i915/intel_lvds.c
> +++ b/drivers/gpu/drm/i915/intel_lvds.c
> @@ -574,6 +574,36 @@ static int intel_lid_notify(struct notifier_block *nb, unsigned long val,
>  	return NOTIFY_OK;
>  }
>  
> +static int
> +intel_lvds_connector_register(struct drm_connector *connector)
> +{
> +	struct intel_lvds_connector *lvds = to_lvds_connector(connector);
> +	int ret;
> +
> +	ret = intel_connector_register(connector);
> +	if (ret)
> +		return ret;
> +
> +	lvds->lid_notifier.notifier_call = intel_lid_notify;
> +	if (acpi_lid_notifier_register(&lvds->lid_notifier)) {
> +		DRM_DEBUG_KMS("lid notifier registration failed\n");
> +		lvds->lid_notifier.notifier_call = NULL;
> +	}
> +
> +	return 0;
> +}
> +
> +static void
> +intel_lvds_connector_unregister(struct drm_connector *connector)
> +{
> +	struct intel_lvds_connector *lvds = to_lvds_connector(connector);
> +
> +	if (lvds->lid_notifier.notifier_call)
> +		acpi_lid_notifier_unregister(&lvds->lid_notifier);
> +
> +	intel_connector_unregister(connector);
> +}
> +
>  /**
>   * intel_lvds_destroy - unregister and free LVDS structures
>   * @connector: connector to free
> @@ -586,9 +616,6 @@ static void intel_lvds_destroy(struct drm_connector *connector)
>  	struct intel_lvds_connector *lvds_connector =
>  		to_lvds_connector(connector);
>  
> -	if (lvds_connector->lid_notifier.notifier_call)
> -		acpi_lid_notifier_unregister(&lvds_connector->lid_notifier);
> -
>  	if (!IS_ERR_OR_NULL(lvds_connector->base.edid))
>  		kfree(lvds_connector->base.edid);
>  
> @@ -609,8 +636,8 @@ static const struct drm_connector_funcs intel_lvds_connector_funcs = {
>  	.fill_modes = drm_helper_probe_single_connector_modes,
>  	.atomic_get_property = intel_digital_connector_atomic_get_property,
>  	.atomic_set_property = intel_digital_connector_atomic_set_property,
> -	.late_register = intel_connector_register,
> -	.early_unregister = intel_connector_unregister,
> +	.late_register = intel_lvds_connector_register,
> +	.early_unregister = intel_lvds_connector_unregister,
>  	.destroy = intel_lvds_destroy,
>  	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
>  	.atomic_duplicate_state = intel_digital_connector_duplicate_state,
> @@ -1150,12 +1177,6 @@ void intel_lvds_init(struct drm_i915_private *dev_priv)
>  
>  	lvds_encoder->a3_power = lvds & LVDS_A3_POWER_MASK;
>  
> -	lvds_connector->lid_notifier.notifier_call = intel_lid_notify;
> -	if (acpi_lid_notifier_register(&lvds_connector->lid_notifier)) {
> -		DRM_DEBUG_KMS("lid notifier registration failed\n");
> -		lvds_connector->lid_notifier.notifier_call = NULL;
> -	}
> -
>  	return;
>  
>  failed:

-- 
Jani Nikula, Intel Open Source Graphics Center
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