I think there are no direct issues with initialization in the state how it is now. I suspect it's because "drm_kms_helper_poll_enable()" starts the first worker thread with a delay, which gives enough time to initialize required resources. I changed the initialization part to keep it consistent with the finish part, which is the one causing troubles.
I am not sure where I could move "drm_kms_helper_poll_enable/disable()", since it is defined in "drm/drm_probe_helper.c", which is only included in "nouveau_display.c" and "nouveau_connector.c". Both creating a new function in "nouveau_display.c", and including "probe_helper.h" and using poll_enable in a different file like "nouveau_fbcon.c" seem like too big changes for such small fix. I don't know.
Can this new proposed order break something in the finish part as well? Maybe it would be just better to change the order of "nouveau_drm_finish" and keep the current order of "noueau_drm_init"?
On Thu, May 5, 2022 at 9:57 PM Lyude Paul lyude@redhat.com wrote:
Hmm, I think we might just need to move the drm_kms_helper_poll_enable() call to the end here instead of all of nouveau_display_init(). I realized this because in nouveau_display_init() it seems that we actually rely on nouveau_display_init() to setup hotplug interrupts - which we do actually need this early on in the driver probe process.
That being said though, drm_kms_helper_poll_enable() shouldn't be required for MST short HPD IRQs from working so moving that instead should work.
On Wed, 2022-05-04 at 19:18 +0200, Mark Menzynski wrote:
Resources needed for output poll workers are destroyed in nouveau_fbcon_fini() before output poll workers are cleared in nouveau_display_fini(). This means there is a time between fbcon_fini and display_fini, where if output poll happens, it crashes.
BUG: KASAN: use-after-free in __drm_fb_helper_initial_config_and_unlock.cold+0x1f3/0x291 [drm_kms_helper]
Cc: Ben Skeggs bskeggs@redhat.com Cc: Karol Herbst kherbst@redhat.com Cc: Lyude Paul lyude@redhat.com Cc: David Airlie airlied@linux.ie Cc: Daniel Vetter daniel@ffwll.ch Cc: Sumit Semwal sumit.semwal@linaro.org Cc: "Christian König" christian.koenig@amd.com Cc: dri-devel@lists.freedesktop.org Cc: nouveau@lists.freedesktop.org Cc: linux-kernel@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Signed-off-by: Mark Menzynski mmenzyns@redhat.com
drivers/gpu/drm/nouveau/nouveau_drm.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c index 561309d447e0..773efdd20d2f 100644 --- a/drivers/gpu/drm/nouveau/nouveau_drm.c +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c @@ -588,12 +588,6 @@ nouveau_drm_device_init(struct drm_device *dev) if (ret) goto fail_dispctor;
if (dev->mode_config.num_crtc) {ret = nouveau_display_init(dev, false, false);if (ret)goto fail_dispinit;}nouveau_debugfs_init(drm); nouveau_hwmon_init(dev); nouveau_svm_init(drm);@@ -601,6 +595,12 @@ nouveau_drm_device_init(struct drm_device *dev) nouveau_fbcon_init(dev); nouveau_led_init(dev);
if (dev->mode_config.num_crtc) {ret = nouveau_display_init(dev, false, false);if (ret)goto fail_dispinit;}if (nouveau_pmops_runtime()) { pm_runtime_use_autosuspend(dev->dev); pm_runtime_set_autosuspend_delay(dev->dev, 5000);@@ -641,15 +641,14 @@ nouveau_drm_device_fini(struct drm_device *dev) pm_runtime_forbid(dev->dev); }
if (dev->mode_config.num_crtc)nouveau_display_fini(dev, false, false); nouveau_led_fini(dev); nouveau_fbcon_fini(dev); nouveau_dmem_fini(drm); nouveau_svm_fini(drm); nouveau_hwmon_fini(dev); nouveau_debugfs_fini(drm);
if (dev->mode_config.num_crtc)nouveau_display_fini(dev, false, false); nouveau_display_destroy(dev); nouveau_accel_fini(drm);-- Cheers, Lyude Paul (she/her) Software Engineer at Red Hat