When closing the DRM device while a vblank is pending, we access file_priv after it has been free'd, which gives:
Unable to handle kernel NULL pointer dereference at virtual address 00000000 ... PC is at __list_add+0x5c/0xe8 LR is at send_vblank_event+0x54/0x1f0 ... [<c02952e8>] (__list_add) from [<c031a7b4>] (send_vblank_event+0x54/0x1f0) [<c031a760>] (send_vblank_event) from [<c031a9c0>] (drm_send_vblank_event+0x70/0x78) [<c031a950>] (drm_send_vblank_event) from [<c031a9f8>] (drm_crtc_send_vblank_event+0x30/0x34) [<c031a9c8>] (drm_crtc_send_vblank_event) from [<c0339ad8>] (vop_isr+0x224/0x28c) [<c03398b4>] (vop_isr) from [<c0081780>] (handle_irq_event_percpu+0x12c/0x3e4)
This can be triggered somewhat reliably with:
modetest -M rockchip -v -s ...
Add a preclose hook to the driver so that we can discard any pending vblank events when the device is closed.
Signed-off-by: John Keeping john@metanate.com --- drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 22 ++++++++++++++++++++++ drivers/gpu/drm/rockchip/rockchip_drm_drv.h | 1 + drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 20 ++++++++++++++++++++ 3 files changed, 43 insertions(+)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c index a0d51cc..1c8a9be 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c @@ -251,6 +251,27 @@ static int rockchip_drm_unload(struct drm_device *drm_dev) return 0; }
+static void rockchip_drm_crtc_cancel_pending_vblank(struct drm_crtc *crtc, + struct drm_file *file_priv) +{ + struct rockchip_drm_private *priv = crtc->dev->dev_private; + int pipe = drm_crtc_index(crtc); + + if (pipe < ROCKCHIP_MAX_CRTC && + priv->crtc_funcs[pipe] && + priv->crtc_funcs[pipe]->cancel_pending_vblank) + priv->crtc_funcs[pipe]->cancel_pending_vblank(crtc, file_priv); +} + +static void rockchip_drm_preclose(struct drm_device *dev, + struct drm_file *file_priv) +{ + struct drm_crtc *crtc; + + list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) + rockchip_drm_crtc_cancel_pending_vblank(crtc, file_priv); +} + void rockchip_drm_lastclose(struct drm_device *dev) { struct rockchip_drm_private *priv = dev->dev_private; @@ -281,6 +302,7 @@ static struct drm_driver rockchip_drm_driver = { DRIVER_PRIME | DRIVER_ATOMIC, .load = rockchip_drm_load, .unload = rockchip_drm_unload, + .preclose = rockchip_drm_preclose, .lastclose = rockchip_drm_lastclose, .get_vblank_counter = drm_vblank_no_hw_counter, .enable_vblank = rockchip_drm_crtc_enable_vblank, diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h index bb8b076..2b41dd4 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h @@ -40,6 +40,7 @@ struct rockchip_crtc_funcs { int (*enable_vblank)(struct drm_crtc *crtc); void (*disable_vblank)(struct drm_crtc *crtc); void (*wait_for_update)(struct drm_crtc *crtc); + void (*cancel_pending_vblank)(struct drm_crtc *crtc, struct drm_file *file_priv); };
struct rockchip_atomic_commit { diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c index 8a5ac57..53dfe21 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c @@ -875,10 +875,30 @@ static void vop_crtc_wait_for_update(struct drm_crtc *crtc) WARN_ON(!wait_for_completion_timeout(&vop->wait_update_complete, 100)); }
+static void vop_crtc_cancel_pending_vblank(struct drm_crtc *crtc, + struct drm_file *file_priv) +{ + struct drm_device *drm = crtc->dev; + struct vop *vop = to_vop(crtc); + struct drm_pending_vblank_event *e; + unsigned long flags; + + spin_lock_irqsave(&drm->event_lock, flags); + e = vop->event; + if (e && e->base.file_priv == file_priv) { + vop->event = NULL; + + e->base.destroy(&e->base); + file_priv->event_space += sizeof(e->event); + } + spin_unlock_irqrestore(&drm->event_lock, flags); +} + static const struct rockchip_crtc_funcs private_crtc_funcs = { .enable_vblank = vop_crtc_enable_vblank, .disable_vblank = vop_crtc_disable_vblank, .wait_for_update = vop_crtc_wait_for_update, + .cancel_pending_vblank = vop_crtc_cancel_pending_vblank, };
static bool vop_crtc_mode_fixup(struct drm_crtc *crtc,