Re: [PATCH] drm/i915: call drm_vblank_cleanup() earlier at unload

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Paulo Zanoni <przanoni@gmail.com>
Cc: intel-gfx@lists.freedesktop.org, Paulo Zanoni <paulo.r.zanoni@intel.com>
Subject: Re: [PATCH] drm/i915: call drm_vblank_cleanup() earlier at unload
Date: Fri, 17 Oct 2014 14:18:34 +0300	[thread overview]
Message-ID: <20141017111834.GS4284@intel.com> (raw)
In-Reply-To: <1413393304-3224-1-git-send-email-przanoni@gmail.com>

On Wed, Oct 15, 2014 at 02:15:04PM -0300, Paulo Zanoni wrote:
> From: Paulo Zanoni <paulo.r.zanoni@intel.com>
> 
> In its current place, it just segfaults while trying to access the
> CRTC structures:
> 
> [ 9132.421681] Call Trace:
> [ 9132.421707]  [<ffffffffa01130d8>] i915_get_crtc_scanoutpos+0x1e8/0x220 [i915]
> [ 9132.421727]  [<ffffffffa001da34>] drm_calc_vbltimestamp_from_scanoutpos+0x94/0x330 [drm]
> [ 9132.421744]  [<ffffffffa001d240>] ?vblank_disable_and_save+0x40/0x1e0 [drm]
> [ 9132.421769]  [<ffffffffa0114328>] i915_get_vblank_timestamp+0x68/0xb0 [i915]
> [ 9132.421786]  [<ffffffffa001d094>] drm_get_last_vbltimestamp+0x44/0x80 [drm]
> [ 9132.421801]  [<ffffffffa001d3a6>] vblank_disable_and_save+0x1a6/0x1e0 [drm]
> [ 9132.421817]  [<ffffffffa001eac1>] drm_vblank_cleanup+0x61/0xa0 [drm]
> [ 9132.421849]  [<ffffffffa0177a5e>] i915_driver_unload+0xde/0x290 [i915]
> [ 9132.421867]  [<ffffffffa0020264>] drm_dev_unregister+0x24/0xb0 [drm]
> [ 9132.421884]  [<ffffffffa002090e>] drm_put_dev+0x1e/0x70 [drm]
> [ 9132.421901]  [<ffffffffa00e01e0>] i915_pci_remove+0x10/0x20 [i915]
> [ 9132.421910]  [<ffffffff81347556>] pci_device_remove+0x36/0xb0
> [ 9132.421920]  [<ffffffff8140084a>] __device_release_driver+0x7a/0xf0
> [ 9132.421928]  [<ffffffff81400fc8>] driver_detach+0xb8/0xc0
> [ 9132.421936]  [<ffffffff8140054a>] bus_remove_driver+0x4a/0xb0
> [ 9132.421944]  [<ffffffff81401717>] driver_unregister+0x27/0x50
> [ 9132.421953]  [<ffffffff81346f65>] pci_unregister_driver+0x25/0x70
> [ 9132.421971]  [<ffffffffa00229c8>] drm_pci_exit+0x78/0xa0 [drm]
> [ 9132.422000]  [<ffffffffa017a6d2>] i915_exit+0x20/0x94e [i915]
> [ 9132.422009]  [<ffffffff810fb9dc>] SyS_delete_module+0x13c/0x1f0
> [ 9132.422019]  [<ffffffff8131c5fb>] ?
> trace_hardirqs_on_thunk+0x3a/0x3f
> [ 9132.422028]  [<ffffffff816f7792>] system_call_fastpath+0x16/0x1b
> 
> This means it has to be before intel_modeset_cleanup, which cleans the
> CRTC structures. But if we move it to before intel_fbdev_fini(), we
> get WARNs because intel_fbdev_fini() still tries to use the vblanks,
> so the only acceptable point for drm_vblank_cleanup() seems to be this
> place.

Hmm. Yeah that seems like the spot we have to put it given it wants
to call the vblank disable hook.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> 
> Related commit:
> 
>     commit cbb47d179fb345c579cd8cd884693903fceed26a
>     Author: Chris Wilson <chris@chris-wilson.co.uk>
>     Date:   Mon Sep 23 17:33:20 2013 -0300
>         drm/i915: Add some missing steps to i915_driver_load error path
> 
> Testsuite: igt/drv_module_reload
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77511
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83484
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_dma.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 85d14e1..1b39807 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1853,8 +1853,12 @@ int i915_driver_unload(struct drm_device *dev)
>  
>  	acpi_video_unregister();
>  
> -	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> +	if (drm_core_check_feature(dev, DRIVER_MODESET))
>  		intel_fbdev_fini(dev);
> +
> +	drm_vblank_cleanup(dev);
> +
> +	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
>  		intel_modeset_cleanup(dev);
>  
>  		/*
> @@ -1895,8 +1899,6 @@ int i915_driver_unload(struct drm_device *dev)
>  			i915_free_hws(dev);
>  	}
>  
> -	drm_vblank_cleanup(dev);
> -
>  	intel_teardown_gmbus(dev);
>  	intel_teardown_mchbar(dev);
>  
> -- 
> 2.1.1
> 
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-- 
Ville Syrjälä
Intel OTC