drm/i915: Don't try to reference the fb in get_initial_plane_config()

Damien Lespiau · airlied · commit 59a58cb34d3f · 2015-03-25T10:01:46.000+10:00
Tvrtko noticed a new warning on boot: WARNING: CPU: 1 PID: 353 at include/linux/kref.h:47 drm_framebuffer_reference+0x6c/0x80 [drm]() Call Trace: [<ffffffff8161f10c>] dump_stack+0x4f/0x7b [<ffffffff81052caa>] warn_slowpath_common+0xaa/0xd0 [<ffffffff81052d8a>] warn_slowpath_null+0x1a/0x20 [<ffffffffa00d035c>] drm_framebuffer_reference+0x6c/0x80 [drm] [<ffffffffa01c0df7>] update_state_fb.isra.54+0x47/0x50 [i915] [<ffffffffa01ccd5c>] skylake_get_initial_plane_config+0x93c/0x950 [i915] [<ffffffffa01e8721>] intel_modeset_init+0x1551/0x17c0 [i915] [<ffffffffa02476e0>] i915_driver_load+0xed0/0x11e0 [i915] [<ffffffff81627aa1>] ? _raw_spin_unlock_irqrestore+0x51/0x70 [<ffffffffa00ca8b7>] drm_dev_register+0x77/0x110 [drm] [<ffffffffa00cda3b>] drm_get_pci_dev+0x11b/0x1f0 [drm] [<ffffffff81098e3d>] ? trace_hardirqs_on+0xd/0x10 [<ffffffff81627aa1>] ? _raw_spin_unlock_irqrestore+0x51/0x70 [<ffffffffa0145276>] i915_pci_probe+0x56/0x60 [i915] [<ffffffff813ad59c>] pci_device_probe+0x7c/0x100 [<ffffffff81466aad>] driver_probe_device+0x16d/0x380 We cannot take a reference at this point, not before intel_framebuffer_init() and the underlying drm_framebuffer_init(). Introduced in: commit 706dc7b549175e47f23e913b7f1e52874a7d0f56 Author: Matt Roper <matthew.d.roper@intel.com> Date: Tue Feb 3 13:10:04 2015 -0800 drm/i915: Ensure plane->state->fb stays in sync with plane->fb v2: Don't move update_state_fb(). It was moved around because I originally put update_state_fb() in intel_alloc_plane_obj() before finding a better place. (Matt) Reviewed-by: Matt Roper <matthew.d.roper@intel.com> Reported-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Matt Roper <matthew.d.roper@intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Signed-off-by: Damien Lespiau <damien.lespiau@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> From drm-next: (cherry picked from commit f55548b) Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
@@ -2438,8 +2438,10 @@ intel_find_plane_obj(struct intel_crtc *intel_crtc,
 	if (!intel_crtc->base.primary->fb)
 		return;
 
-	if (intel_alloc_plane_obj(intel_crtc, plane_config))
+	if (intel_alloc_plane_obj(intel_crtc, plane_config)) {
+		update_state_fb(intel_crtc->base.primary);
 		return;
+	}
 
 	kfree(intel_crtc->base.primary->fb);
 	intel_crtc->base.primary->fb = NULL;
@@ -6663,7 +6665,6 @@ i9xx_get_initial_plane_config(struct intel_crtc *crtc,
 		      plane_config->size);
 
 	crtc->base.primary->fb = fb;
-	update_state_fb(crtc->base.primary);
 }
 
 static void chv_crtc_clock_get(struct intel_crtc *crtc,
@@ -7704,7 +7705,6 @@ skylake_get_initial_plane_config(struct intel_crtc *crtc,
 		      plane_config->size);
 
 	crtc->base.primary->fb = fb;
-	update_state_fb(crtc->base.primary);
 	return;
 
 error:
@@ -7798,7 +7798,6 @@ ironlake_get_initial_plane_config(struct intel_crtc *crtc,
 		      plane_config->size);
 
 	crtc->base.primary->fb = fb;
-	update_state_fb(crtc->base.primary);
 }
 
 static bool ironlake_get_pipe_config(struct intel_crtc *crtc,
