Hi Sean,
On 04/06/2017 08:26 PM, Sean Paul wrote:
On Thu, Apr 06, 2017 at 10:47:59AM +0800, jeffy wrote:
Hi Sean,
On 04/06/2017 12:28 AM, Sean Paul wrote:
On Wed, Apr 05, 2017 at 04:29:26PM +0800, Jeffy Chen wrote:
After unbinding drm, the userspace may still has a chance to access
gem buf.
Add a sanity check for a NULL dev_private to prevent that from
happening.
I still don't understand how this is happening. You're saying that these hooks
can be called after rockchip_drm_unbind() has finished?
yes, tested on chromebook rk3399 kevin with kernel 4.4, if trigger unbind
without killing display service(ui or frecon):
[ 31.276889] [<ffffffc0002089e4>] dump_backtrace+0x0/0x164
[ 31.282288] [<ffffffc000208b6c>] show_stack+0x24/0x30
[ 31.287338] [<ffffffc0004be028>] dump_stack+0x98/0xb8
[ 31.292389] [<ffffffc0005c0b8c>] rockchip_gem_create_object+0x6c/0x2ec
[ 31.298910] [<ffffffc0005c0fa0>]
rockchip_gem_create_with_handle+0x38/0x10c
[ 31.305868] [<ffffffc0005c12b8>] rockchip_gem_create_ioctl+0x38/0x50
[ 31.312221] [<ffffffc000598844>] drm_ioctl+0x2bc/0x438
[ 31.317359] [<ffffffc0005b5ee0>] drm_compat_ioctl+0x3c/0x70
[ 31.322935] [<ffffffc0003a6960>] compat_SyS_ioctl+0x134/0x1048
[ 31.328766] [<ffffffc000203e90>] __sys_trace_return+0x0/0x4
Hi Jeffy,
I'm not suggesting this doesn't happen, I believe you :-). I'd really like to
know *why* it happens.
Are you sure that unbind has completely finished before this trace occurs?
Perhaps this is results from a race between unbind and gem allocate?
yes, that unbind is finished. and it looks like the display server still
holds drm dev fd(even it been deleted after unbind).
sometimes i can see it trigger ioctl even seconds later.
i'll send a patch to break drm_ioctl after unbind.
Sean
Sean
Signed-off-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>
---
Changes in v3:
Address Daniel Vetter <daniel@xxxxxxxx>'s comments.
Update commit message.
Changes in v2: None
drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
index df9e570..205a3dc 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
@@ -184,6 +184,9 @@ static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj,
struct drm_device *drm = obj->dev;
struct rockchip_drm_private *private = drm->dev_private;
+ if (!private)
+ return -ENODEV;
+
if (private->domain)
return rockchip_gem_alloc_iommu(rk_obj, alloc_kmap);
else
@@ -208,6 +211,11 @@ static void rockchip_gem_free_dma(struct rockchip_gem_object *rk_obj)
static void rockchip_gem_free_buf(struct rockchip_gem_object *rk_obj)
{
+ struct drm_device *drm = rk_obj->base.dev;
+
+ if (!drm->dev_private)
+ return;
+
if (rk_obj->pages)
rockchip_gem_free_iommu(rk_obj);
else
--
2.1.4
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