Re: [PATCH] drm/i915: Cancel the modeset retry work during modeset cleanup

[Manasi Navare <manasi.d.navare@intel.com>]

On Thu, Oct 26, 2017 at 07:33:44AM +0100, Chris Wilson wrote:
> Quoting Manasi Navare (2017-10-26 02:20:04)
> > During modeset cleanup on driver unload we may have a pending
> > hotplug work. This needs to be cancel early during the teardown
> > so that it does not fire after we have freed the connector.
> > We do this after drm_kms_helper_poll_fini(dev) since this might
> > cause link retrain and before intel_fbdev_fini() since this tries to
> > free the connector.
> > 
> > If this is not done we may see something like:
> > DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock))
> >  ------------[ cut here ]------------
> >  WARNING: CPU: 4 PID: 5010 at kernel/locking/mutex-debug.c:103 mutex_destroy+0x4e/0x60
> >  Modules linked in: i915(-) snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_codec snd_hwdep snd_hda_core snd_pcm vgem ax88179_178
> > +a usbnet mii x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel e1000e ptp pps_core prime_numbers i2c_hid
> > +[last unloaded: snd_hda_intel]
> >  CPU: 4 PID: 5010 Comm: drv_module_relo Tainted: G     U          4.14.0-rc3-CI-CI_DRM_3186+ #1
> >  Hardware name: Intel Corporation CoffeeLake Client Platform/CoffeeLake S UDIMM RVP, BIOS CNLSFWX1.R00.X104.A03.1709140524 09/14/2017
> >  task: ffff8803c827aa40 task.stack: ffffc90000520000
> >  RIP: 0010:mutex_destroy+0x4e/0x60
> >  RSP: 0018:ffffc90000523d58 EFLAGS: 00010292
> >  RAX: 000000000000002a RBX: ffff88044fbef648 RCX: 0000000000000000
> >  RDX: 0000000080000001 RSI: 0000000000000001 RDI: ffffffff810f0cf0
> >  RBP: ffffc90000523d60 R08: 0000000000000001 R09: 0000000000000001
> >  R10: 000000000f21cb81 R11: 0000000000000000 R12: ffff88044f71efc8
> >  R13: ffffffffa02b3d20 R14: ffffffffa02b3d90 R15: ffff880459b29308
> >  FS:  00007f5df4d6e8c0(0000) GS:ffff88045d300000(0000) knlGS:0000000000000000
> >  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >  CR2: 000055ec51f00a18 CR3: 0000000451782006 CR4: 00000000003606e0
> >  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> >  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> >  Call Trace:
> >   drm_fb_helper_fini+0xd9/0x130
> >   intel_fbdev_destroy+0x12/0x60 [i915]
> >   intel_fbdev_fini+0x28/0x30 [i915]
> >   intel_modeset_cleanup+0x45/0xa0 [i915]
> >   i915_driver_unload+0x92/0x180 [i915]
> >   i915_pci_remove+0x19/0x30 [i915]
> >   i915_driver_unload+0x92/0x180 [i915]
> >   i915_pci_remove+0x19/0x30 [i915]
> >   pci_device_remove+0x39/0xb0
> >   device_release_driver_internal+0x15d/0x220
> >   driver_detach+0x40/0x80
> >   bus_remove_driver+0x58/0xd0
> >   driver_unregister+0x2c/0x40
> >   pci_unregister_driver+0x36/0xb0
> >   i915_exit+0x1a/0x8b [i915]
> >   SyS_delete_module+0x18c/0x1e0
> >   entry_SYSCALL_64_fastpath+0x1c/0xb1
> >  RIP: 0033:0x7f5df3286287
> >  RSP: 002b:00007fff8e107cc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000b0
> >  RAX: ffffffffffffffda RBX: ffffffff81493a03 RCX: 00007f5df3286287
> >  RDX: 0000000000000001 RSI: 0000000000000800 RDI: 0000564c7be02e48
> >  RBP: ffffc90000523f88 R08: 0000000000000000 R09: 0000000000000080
> >  R10: 00007f5df4d6e8c0 R11: 0000000000000246 R12: 0000000000000000
> >  R13: 00007fff8e107eb0 R14: 0000000000000000 R15: 0000000000000000
> > 
> > Suggested-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Fixes: 9301397a63b3 ("drm/i915: Implement Link Rate fallback on Link training failure")
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Tony Cheng <tony.cheng@amd.com>
> > Cc: Harry Wentland <Harry.wentland@amd.com>
> > Cc: Jani Nikula <jani.nikula@linux.intel.com>
> > Cc: Daniel Vetter <daniel.vetter@intel.com>
> > Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> > Cc: Manasi Navare <manasi.d.navare@intel.com>
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.h      |  1 +
> >  drivers/gpu/drm/i915/intel_display.c | 16 ++++++++++++++++
> >  2 files changed, 17 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > index 366ba74..f81b073 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -4114,6 +4114,7 @@ extern void intel_modeset_gem_init(struct drm_device *dev);
> >  extern void intel_modeset_cleanup(struct drm_device *dev);
> >  extern int intel_connector_register(struct drm_connector *);
> >  extern void intel_connector_unregister(struct drm_connector *);
> > +extern void intel_connector_work_fn_cleanup(struct drm_device *dev);
> >  extern int intel_modeset_vga_set_state(struct drm_i915_private *dev_priv,
> >                                        bool state);
> >  extern void intel_display_resume(struct drm_device *dev);
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 0e493a1..44158ff 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -15200,6 +15200,19 @@ void intel_connector_unregister(struct drm_connector *connector)
> >         intel_panel_destroy_backlight(connector);
> >  }
> >  
> > +void intel_connector_work_fn_cleanup(struct drm_device *dev)
> ^static
>

Yes will make this static

 
> > +{
> > +       struct intel_connector *connector;
> > +       struct drm_connector_list_iter conn_iter;
> > +
> > +       drm_connector_list_iter_begin(dev, &conn_iter);
> > +       for_each_intel_connector_iter(connector, &conn_iter) {
> > +               if (connector->modeset_retry_work.func)
> > +                       cancel_work_sync(&connector->modeset_retry_work);
> > +       }
> > +       drm_connector_list_iter_end(&conn_iter);
> > +}
> > +
> >  void intel_modeset_cleanup(struct drm_device *dev)
> >  {
> >         struct drm_i915_private *dev_priv = to_i915(dev);
> > @@ -15222,6 +15235,9 @@ void intel_modeset_cleanup(struct drm_device *dev)
> >          */
> >         drm_kms_helper_poll_fini(dev);
> >  
> > +       /* Cancel pending modeset retry work in intel_connector */
> > +       intel_connector_work_fn_cleanup(dev);
> 
> If you call this intel_hpd_poll_fini() and do both the helper_poll_fini
> and the cancel_work_sync() afterwards, the coupling between the two is
> more obvious.
> -Chris

So rename this function as intel_hpd_poll_fini() that will call drm_kms_helper_fini() first
and then loop through the connector list and cancel_work_sync()? 

Manasi
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