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authorDaniel Vetter <daniel.vetter@ffwll.ch>2014-12-08 22:55:22 +0100
committerDave Airlie <airlied@redhat.com>2014-12-09 09:56:45 +1000
commit0391359ddf79b52bb7e7bb9ace08e34fb08b0e76 (patch)
tree73342c78e3c858786c8c876d620112d1ace2199d /Documentation/DocBook/drm.tmpl
parentdrm/fb_helper: move deferred fb checking into restore mode (v2) (diff)
downloadlinux-dev-0391359ddf79b52bb7e7bb9ace08e34fb08b0e76.tar.xz
linux-dev-0391359ddf79b52bb7e7bb9ace08e34fb08b0e76.zip
drm/dp-mst: Remove branches before dropping the reference
When we unplug a dp mst branch we unreference the entire tree from the root towards the leaves. Which is ok, since that's the way the pointers and so also the refcounts go. But when we drop the reference we must make sure that we remove the branches/ports from the lists/pointers before dropping the reference. Otherwise the get_validated functions will still return it instead of returning NULL (which indicates a potentially on-going unplug). The mst branch destroy gets this right for ports: First it deletes the port from the ports list, then it unrefs. But the ports destroy function gets it wrong: First it unrefs, then it drops the ref. Which means a zombie mst branch can still be validate with get_validated_mstb_ref when it shouldn't. Fix this. This should address a backtrace Dave dug out somewhere on unplug: [<ffffffffa00cc262>] drm_dp_mst_get_validated_mstb_ref_locked+0x92/0xa0 [drm_kms_helper] [<ffffffffa00cc211>] drm_dp_mst_get_validated_mstb_ref_locked+0x41/0xa0 [drm_kms_helper] [<ffffffffa00cc2aa>] drm_dp_get_validated_mstb_ref+0x3a/0x60 [drm_kms_helper] [<ffffffffa00cc2fb>] drm_dp_payload_send_msg.isra.14+0x2b/0x100 [drm_kms_helper] [<ffffffffa00cc547>] drm_dp_update_payload_part1+0x177/0x360 [drm_kms_helper] [<ffffffffa015c52e>] intel_mst_disable_dp+0x3e/0x80 [i915] [<ffffffffa013d60b>] haswell_crtc_disable+0x1cb/0x340 [i915] [<ffffffffa0136739>] intel_crtc_control+0x49/0x100 [i915] [<ffffffffa0136857>] intel_crtc_update_dpms+0x67/0x80 [i915] [<ffffffffa013fa59>] intel_connector_dpms+0x59/0x70 [i915] [<ffffffffa015c752>] intel_dp_destroy_mst_connector+0x32/0xc0 [i915] [<ffffffffa00cb44b>] drm_dp_destroy_port+0x6b/0xa0 [drm_kms_helper] [<ffffffffa00cb588>] drm_dp_destroy_mst_branch_device+0x108/0x130 [drm_kms_helper] [<ffffffffa00cb3cd>] drm_dp_port_teardown_pdt+0x3d/0x50 [drm_kms_helper] [<ffffffffa00cdb79>] drm_dp_mst_handle_up_req+0x499/0x540 [drm_kms_helper] [<ffffffff810d9ead>] ? trace_hardirqs_on_caller+0x15d/0x200 [<ffffffffa00cdc73>] drm_dp_mst_hpd_irq+0x53/0xa00 [drm_kms_helper] [<ffffffffa00c7dfb>] ? drm_dp_dpcd_read+0x1b/0x20 [drm_kms_helper] [<ffffffffa0153ed8>] ? intel_dp_dpcd_read_wake+0x38/0x70 [i915] [<ffffffffa015a225>] intel_dp_check_mst_status+0xb5/0x250 [i915] [<ffffffffa015ac71>] intel_dp_hpd_pulse+0x181/0x210 [i915] [<ffffffffa01104f6>] i915_digport_work_func+0x96/0x120 [i915] Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'Documentation/DocBook/drm.tmpl')
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