* [PATCH] drm/mst: use kref_get_unless_zero for looking up mst branch device @ 2014-11-10 6:41 Dave Airlie 2014-11-10 8:34 ` [Intel-gfx] " Daniel Vetter 2014-11-10 14:40 ` [PATCH] drm/mst: use kref_get_unless_zero for looking shuang.he 0 siblings, 2 replies; 3+ messages in thread From: Dave Airlie @ 2014-11-10 6:41 UTC (permalink / raw) To: dri-devel, intel-gfx From: Dave Airlie <airlied@redhat.com> The backtrace below shows that while we tear down a branch device, when we remove the connector, we can attempt to disable MST on the port we are tearing down, since the port is going away, there it has a refcount of 0 already, so the validated ref lookup is trying to kref_get again and failing. Use kref_get_unless_zero and just don't return anything if we are looking up the object we are currently also cleaning. [<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: Dave Airlie <airlied@redhat.com> --- drivers/gpu/drm/drm_dp_mst_topology.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index ce1113c..f703a5b 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -882,8 +882,10 @@ static struct drm_dp_mst_branch *drm_dp_mst_get_validated_mstb_ref_locked(struct struct drm_dp_mst_port *port; struct drm_dp_mst_branch *rmstb; if (to_find == mstb) { - kref_get(&mstb->kref); - return mstb; + if (!kref_get_unless_zero(&mstb->kref)) + return NULL; + else + return mstb; } list_for_each_entry(port, &mstb->ports, next) { if (port->mstb) { -- 2.1.0 _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [Intel-gfx] [PATCH] drm/mst: use kref_get_unless_zero for looking up mst branch device 2014-11-10 6:41 [PATCH] drm/mst: use kref_get_unless_zero for looking up mst branch device Dave Airlie @ 2014-11-10 8:34 ` Daniel Vetter 2014-11-10 14:40 ` [PATCH] drm/mst: use kref_get_unless_zero for looking shuang.he 1 sibling, 0 replies; 3+ messages in thread From: Daniel Vetter @ 2014-11-10 8:34 UTC (permalink / raw) To: Dave Airlie; +Cc: intel-gfx, dri-devel On Mon, Nov 10, 2014 at 7:41 AM, Dave Airlie <airlied@gmail.com> wrote: > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c > index ce1113c..f703a5b 100644 > --- a/drivers/gpu/drm/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c > @@ -882,8 +882,10 @@ static struct drm_dp_mst_branch *drm_dp_mst_get_validated_mstb_ref_locked(struct > struct drm_dp_mst_port *port; > struct drm_dp_mst_branch *rmstb; > if (to_find == mstb) { > - kref_get(&mstb->kref); > - return mstb; > + if (!kref_get_unless_zero(&mstb->kref)) > + return NULL; > + else > + return mstb; > } > list_for_each_entry(port, &mstb->ports, next) { > if (port->mstb) { kref_get_unless_zero only works with the lookup structure is protected through some locking. But the list removal in drm_dp_destroy_mst_branch_device is outside the mgr->glock, so that needs to be moved I think. That's not directly required by kref_get_unless_zero, just another effect of the ports list not holding a full reference. Aside for paranoia I'd put a mutex check next to the kref_get_unles_zero, just to document which lock protects this weak reference. And even more tangential: We should probably flatten the recursion, or add a comment stating that the dp spec limits recursion sufficiently. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] drm/mst: use kref_get_unless_zero for looking 2014-11-10 6:41 [PATCH] drm/mst: use kref_get_unless_zero for looking up mst branch device Dave Airlie 2014-11-10 8:34 ` [Intel-gfx] " Daniel Vetter @ 2014-11-10 14:40 ` shuang.he 1 sibling, 0 replies; 3+ messages in thread From: shuang.he @ 2014-11-10 14:40 UTC (permalink / raw) To: shuang.he, intel-gfx, airlied Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he@intel.com) -------------------------------------Summary------------------------------------- Platform: baseline_drm_intel_nightly_pass_rate->patch_applied_pass_rate BYT: pass/total=249/348->248/348 PNV: pass/total=323/328->325/328 ILK: pass/total=328/330->330/330 IVB: pass/total=545/546->545/546 SNB: pass/total=551/556->550/556 HSW: pass/total=577/581->570/581 BDW: pass/total=435/435->434/435 -------------------------------------Detailed------------------------------------- test_platform: test_suite, test_case, result_with_drm_intel_nightly(count, machine_id...)...->result_with_patch_applied(count, machine_id)... BYT: Intel_gpu_tools, igt_gem_bad_reloc_negative-reloc-lut, PASS(4, M36) -> NSPT(1, M36)PASS(3, M36) PNV: Intel_gpu_tools, igt_gem_concurrent_blit_gpu-bcs-early-read, PASS(6, M23M24) -> DMESG_WARN(1, M24)PASS(3, M24) PNV: Intel_gpu_tools, igt_gem_linear_blits_normal, NSPT(1, M23)PASS(3, M24) -> PASS(4, M24) PNV: Intel_gpu_tools, igt_gem_mmap_offset_exhaustion, DMESG_WARN(2, M23M24)PASS(2, M24) -> PASS(4, M24) PNV: Intel_gpu_tools, igt_gem_unref_active_buffers, DMESG_WARN(1, M23)PASS(3, M24) -> PASS(4, M24) ILK: Intel_gpu_tools, igt_kms_render_gpu-blit, DMESG_WARN(1, M26)PASS(3, M6) -> PASS(4, M6) ILK: Intel_gpu_tools, igt_kms_flip_wf_vblank-vs-dpms-interruptible, DMESG_WARN(1, M26)PASS(3, M6) -> PASS(4, M6) IVB: Intel_gpu_tools, igt_gem_bad_reloc_negative-reloc, NSPT(1, M4)PASS(3, M34M4) -> NSPT(2, M4)PASS(2, M4) IVB: Intel_gpu_tools, igt_kms_plane_plane-position-covered-pipe-A-plane-1, TIMEOUT(1, M34)PASS(3, M4) -> PASS(4, M4) SNB: Intel_gpu_tools, igt_gem_concurrent_blit_gpuX-bcs-overwrite-source-forked, PASS(4, M35M22) -> FAIL(1, M22)PASS(3, M22) HSW: Intel_gpu_tools, igt_gem_bad_reloc_negative-reloc, NSPT(1, M39)PASS(3, M40M39) -> NSPT(2, M39)PASS(2, M39) HSW: Intel_gpu_tools, igt_kms_cursor_crc_cursor-128x128-onscreen, PASS(4, M40M39) -> DMESG_WARN(2, M39)PASS(2, M39) HSW: Intel_gpu_tools, igt_kms_cursor_crc_cursor-256x256-offscreen, PASS(4, M40M39) -> DMESG_WARN(2, M39)PASS(2, M39) HSW: Intel_gpu_tools, igt_kms_cursor_crc_cursor-64x64-offscreen, DMESG_WARN(1, M39)PASS(3, M40M39) -> DMESG_WARN(2, M39)PASS(2, M39) HSW: Intel_gpu_tools, igt_kms_cursor_crc_cursor-64x64-onscreen, DMESG_WARN(1, M39)PASS(3, M40M39) -> DMESG_WARN(1, M39)PASS(3, M39) HSW: Intel_gpu_tools, igt_kms_cursor_crc_cursor-64x64-sliding, DMESG_WARN(1, M39)PASS(3, M40M39) -> DMESG_WARN(1, M39)PASS(3, M39) HSW: Intel_gpu_tools, igt_kms_mmio_vs_cs_flip_setplane_vs_cs_flip, PASS(4, M40M39) -> DMESG_WARN(1, M39)PASS(3, M39) BDW: Intel_gpu_tools, igt_gem_reset_stats_ban-bsd, PASS(4, M30) -> DMESG_WARN(1, M30)PASS(3, M30) _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2014-11-10 14:40 UTC | newest] Thread overview: 3+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2014-11-10 6:41 [PATCH] drm/mst: use kref_get_unless_zero for looking up mst branch device Dave Airlie 2014-11-10 8:34 ` [Intel-gfx] " Daniel Vetter 2014-11-10 14:40 ` [PATCH] drm/mst: use kref_get_unless_zero for looking shuang.he
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