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* [PATCH v2] drm/i915: Discard previous atomic state on resume if connectors change
@ 2016-05-06 21:39 Lyude
  2016-05-09  6:42 ` Daniel Vetter
  2016-05-09 14:52 ` ✗ Fi.CI.BAT: failure for drm/i915: Discard previous atomic state on resume if connectors change (rev2) Patchwork
  0 siblings, 2 replies; 6+ messages in thread
From: Lyude @ 2016-05-06 21:39 UTC (permalink / raw)
  To: intel-gfx
  Cc: stable,
	open list:INTEL DRM DRIVERS excluding Poulsbo, Moorestow..., linux-kernel@vger.kernel.org open list,
	Daniel Vetter, Lyude

If an MST device is disconnected while the machine is suspended, the
number of connectors will change as well after we call
intel_dp_mst_resume(). This means that any previous atomic state we had
before suspending is no longer valid, since it'll still be pointing to
missing connectors. We need to check for this before committing the
state, otherwise we'll kernel panic on resume whenever if any MST
display was disconnected before we started resuming:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: [<ffffffffa01588ef>] drm_atomic_helper_check_modeset+0x29f/0xb40 [drm_kms_helper]
Call Trace:
 [<ffffffffa02354f4>] intel_atomic_check+0x34/0x1180 [i915]
 [<ffffffff810e6c3f>] ? mark_held_locks+0x6f/0xa0
 [<ffffffff810e6d99>] ? trace_hardirqs_on_caller+0x129/0x1b0
 [<ffffffffa00ff1d2>] drm_atomic_check_only+0x192/0x620 [drm]
 [<ffffffff813ee001>] ? pci_pm_thaw+0x21/0x90
 [<ffffffffa00ff677>] drm_atomic_commit+0x17/0x60 [drm]
 [<ffffffffa023e0ad>] intel_display_resume+0xbd/0x160 [i915]
 [<ffffffff813ee070>] ? pci_pm_thaw+0x90/0x90
 [<ffffffffa01b60d8>] i915_drm_resume+0xd8/0x160 [i915]
 [<ffffffffa01b6185>] i915_pm_resume+0x25/0x30 [i915]
 [<ffffffff813ee0d4>] pci_pm_resume+0x64/0xa0
 [<ffffffff814d9ea0>] dpm_run_callback+0x90/0x190
 [<ffffffff814da455>] device_resume+0xd5/0x1f0
 [<ffffffff814da58d>] async_resume+0x1d/0x50
 [<ffffffff810b6718>] async_run_entry_fn+0x48/0x150
 [<ffffffff810acc19>] process_one_work+0x1e9/0x5c0
 [<ffffffff810acb96>] ? process_one_work+0x166/0x5c0
 [<ffffffff810ad038>] worker_thread+0x48/0x4e0
 [<ffffffff810acff0>] ? process_one_work+0x5c0/0x5c0
 [<ffffffff810b3794>] kthread+0xe4/0x100
 [<ffffffff81742672>] ret_from_fork+0x22/0x50
 [<ffffffff810b36b0>] ? kthread_create_on_node+0x200/0x200

Changes since v1:
  - Move drm_atomic_state_free() call down so we're holding the
    appropriate locks when destroying the atomic state

Cc: stable@vger.kernel.org
Signed-off-by: Lyude <cpaul@redhat.com>
---
 drivers/gpu/drm/i915/intel_display.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0f29ef6..d68efc7 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -15934,6 +15934,18 @@ void intel_display_resume(struct drm_device *dev)
 retry:
 	ret = drm_modeset_lock_all_ctx(dev, &ctx);
 
+	/*
+	 * With MST, the number of connectors can change between suspend and
+	 * resume, which means that the state we want to restore might now be
+	 * impossible to use since it'll be pointing to non-existant
+	 * connectors.
+	 */
+	if (ret == 0 &&
+	    state->num_connector != dev->mode_config.num_connector) {
+		drm_atomic_state_free(state);
+		state = NULL;
+	}
+
 	if (ret == 0 && !setup) {
 		setup = true;
 
-- 
2.5.5

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^ permalink raw reply related	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2016-05-09 15:31 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2016-05-06 21:39 [PATCH v2] drm/i915: Discard previous atomic state on resume if connectors change Lyude
2016-05-09  6:42 ` Daniel Vetter
2016-05-09 14:07   ` Lyude Paul
2016-05-09 14:53     ` Daniel Vetter
2016-05-09 15:31       ` Lyude Paul
2016-05-09 14:52 ` ✗ Fi.CI.BAT: failure for drm/i915: Discard previous atomic state on resume if connectors change (rev2) Patchwork

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