Re: [RFC] drm/exynos: abort commit when framebuffer is removed from plane

[Inki Dae <inki.dae@samsung.com>]

On 2014년 07월 09일 20:06, Rahul Sharma wrote:
> On 8 July 2014 21:25, Inki Dae <inki.dae@samsung.com> wrote:
>> 2014-06-20 0:13 GMT+09:00 Rahul Sharma <rahul.sharma@samsung.com>:
>>> This situation arises when userspace remove the frambuffer object
>>> and call setmode ioctl.
>>>
>>> drm_mode_rmfb --> drm_plane_force_disable --> plane->crtc = NULL;
>>> and
>>> drm_mode_setcrtc --> exynos_plane_commit --> passes plane->crtc to
>>> exynos_drm_crtc_plane_commit which is NULL.
>>
>> If user process requested drm_mode_rmfb with a fb_id, fb object to the
>> fb_id must be removed from crtc_idr table. So drm_mode_setcrtc should
>> be failed because there is no the fb object in the crtc_idr table
>> anymore.
>> I cannot understand how exynos_drm_crtc_plane_commit function could be
>> called. Can you give me more details?
> 
> Inki,
> 
> These logs should clarify more about the problem:

Thanks. And how can I reenact below problem? if we could reenact this
problem, we may find out fundamental problem and resolve it in more
generic. Can I get example code?

Thanks,
Inki Dae

> 
> localhost ~ # halt
> localhost ~ # [  130.570309] init: debugd main process (781) killed by
> TERM signal
> [  130.602453] init: lid_touchpad_helper main process (2100) killed by
> TERM signal
> [  131.374955] CPU: 2 PID: 834 Comm: X Tainted: G        W     3.16.0-rc1+ #623
> [  131.380558] [<c00155b8>] (unwind_backtrace) from [<c001213c>]
> (show_stack+0x20/0x24)
> [  131.388327] [<c001213c>] (show_stack) from [<c05217d4>]
> (dump_stack+0x7c/0x98)
> [  131.395522] [<c05217d4>] (dump_stack) from [<c02ab7e4>]
> (exynos_drm_crtc_plane_commit+0x20/0x40)
> [  131.404263] [<c02ab7e4>] (exynos_drm_crtc_plane_commit) from
> [<c02ae28c>] (exynos_plane_commit+0x24/0x28)
> [  131.413779] [<c02ae28c>] (exynos_plane_commit) from [<c02ab1c8>]
> (exynos_drm_crtc_commit+0x2c/0x54)
> [  131.422802] [<c02ab1c8>] (exynos_drm_crtc_commit) from [<c02ab2c0>]
> (exynos_drm_crtc_mode_set_commit.isra.1+0x8c/0xa0)
> [  131.433468] [<c02ab2c0>] (exynos_drm_crtc_mode_set_commit.isra.1)
> from [<c02ab3f0>] (exynos_drm_crtc_page_flip+0x100/0x174)
> [  131.444587] [<c02ab3f0>] (exynos_drm_crtc_page_flip) from
> [<c02a1ab4>] (drm_mode_page_flip_ioctl+0x1f0/0x2b0)
> -->> [  131.454460] [<c02a1ab4>] (drm_mode_page_flip_ioctl) from
> [<c0292cb4>] (drm_ioctl+0x270/0x44c)
> [  131.462966] [<c0292cb4>] (drm_ioctl) from [<c011302c>]
> (do_vfs_ioctl+0x4e4/0x5a0)
> [  131.470397] [<c011302c>] (do_vfs_ioctl) from [<c0113144>]
> (SyS_ioctl+0x5c/0x84)
> [  131.477728] [<c0113144>] (SyS_ioctl) from [<c000e380>]
> (ret_fast_syscall+0x0/0x30)
> [  131.762797] CPU: 1 PID: 834 Comm: X Tainted: G        W     3.16.0-rc1+ #623
> [  131.768378] [<c00155b8>] (unwind_backtrace) from [<c001213c>]
> (show_stack+0x20/0x24)
> [  131.776151] [<c001213c>] (show_stack) from [<c05217d4>]
> (dump_stack+0x7c/0x98)
> [  131.783315] [<c05217d4>] (dump_stack) from [<c029c130>]
> (drm_plane_force_disable+0x5c/0x68)
> [  131.791658] [<c029c130>] (drm_plane_force_disable) from
> [<c029cf68>] (drm_framebuffer_remove+0xe4/0x110)
> [  131.801070] [<c029cf68>] (drm_framebuffer_remove) from [<c02a09c0>]
> (drm_mode_rmfb+0xd4/0xfc)
> -->> [  131.809597] [<c02a09c0>] (drm_mode_rmfb) from [<c0292cb4>]
> (drm_ioctl+0x270/0x44c)
> [  131.817135] [<c0292cb4>] (drm_ioctl) from [<c011302c>]
> (do_vfs_ioctl+0x4e4/0x5a0)
> [  131.824609] [<c011302c>] (do_vfs_ioctl) from [<c0113144>]
> (SyS_ioctl+0x5c/0x84)
> [  131.831884] [<c0113144>] (SyS_ioctl) from [<c000e380>]
> (ret_fast_syscall+0x0/0x30)
> [  132.077803] CPU: 0 PID: 834 Comm: X Tainted: G        W     3.16.0-rc1+ #623
> [  132.083413] [<c00155b8>] (unwind_backtrace) from [<c001213c>]
> (show_stack+0x20/0x24)
> [  132.091111] [<c001213c>] (show_stack) from [<c05217d4>]
> (dump_stack+0x7c/0x98)
> [  132.098343] [<c05217d4>] (dump_stack) from [<c02ab7e4>]
> (exynos_drm_crtc_plane_commit+0x20/0x40)
> [  132.107098] [<c02ab7e4>] (exynos_drm_crtc_plane_commit) from
> [<c02ae28c>] (exynos_plane_commit+0x24/0x28)
> [  132.116631] [<c02ae28c>] (exynos_plane_commit) from [<c02ab1c8>]
> (exynos_drm_crtc_commit+0x2c/0x54)
> [  132.125660] [<c02ab1c8>] (exynos_drm_crtc_commit) from [<c02ab2c0>]
> (exynos_drm_crtc_mode_set_commit.isra.1+0x8c/0xa0)
> [  132.136330] [<c02ab2c0>] (exynos_drm_crtc_mode_set_commit.isra.1)
> from [<c02ab2ec>] (exynos_drm_crtc_mode_set_base+0x18/0x1c)
> [  132.147605] [<c02ab2ec>] (exynos_drm_crtc_mode_set_base) from
> [<c028c148>] (drm_crtc_helper_set_config+0x828/0x8a4)
> [  132.158029] [<c028c148>] (drm_crtc_helper_set_config) from
> [<c029ce1c>] (drm_mode_set_config_internal+0x58/0xc0)
> [  132.168155] [<c029ce1c>] (drm_mode_set_config_internal) from
> [<c029fe64>] (drm_mode_setcrtc+0x388/0x4ac)
> -->> [  132.177630] [<c029fe64>] (drm_mode_setcrtc) from [<c0292cb4>]
> (drm_ioctl+0x270/0x44c)
> [  132.185417] [<c0292cb4>] (drm_ioctl) from [<c011302c>]
> (do_vfs_ioctl+0x4e4/0x5a0)
> [  132.192897] [<c011302c>] (do_vfs_ioctl) from [<c0113144>]
> (SyS_ioctl+0x5c/0x84)
> [  132.200138] [<c0113144>] (SyS_ioctl) from [<c000e380>]
> (ret_fast_syscall+0x0/0x30)
> [  132.207735] Unable to handle kernel NULL pointer dereference at
> virtual address 0000032c
> ..
> ..
> [  132.510786] ff80: b6ebdeb8 bee1d5e8 c06864a2 00000036 c000e5a4
> ecf0e000 00000000 ecf0ffa8
> [  132.518941] ffa0: c000e380 c01130f4 b6ebdeb8 bee1d5e8 00000005
> c06864a2 bee1d5e8 00000001
> [  132.527095] ffc0: b6ebdeb8 bee1d5e8 c06864a2 00000036 b85d4a74
> b8702a60 00000000 bee1d688
> [  132.535250] ffe0: b6a82f30 bee1d5cc b6a75cff b6bce50c 00000010
> 00000005 e1a0c00d e92dd800
> [  132.543408] [<c02ab7e4>] (exynos_drm_crtc_plane_commit) from
> [<c02ae28c>] (exynos_plane_commit+0x24/0x28)
> [  132.552949] [<c02ae28c>] (exynos_plane_commit) from [<c02ab1c8>]
> (exynos_drm_crtc_commit+0x2c/0x54)
> [  132.561971] [<c02ab1c8>] (exynos_drm_crtc_commit) from [<c02ab2c0>]
> (exynos_drm_crtc_mode_set_commit.isra.1+0x8c/0xa0)
> [  132.572641] [<c02ab2c0>] (exynos_drm_crtc_mode_set_commit.isra.1)
> from [<c02ab2ec>] (exynos_drm_crtc_mode_set_base+0x18/0x1c)
> [  132.583919] [<c02ab2ec>] (exynos_drm_crtc_mode_set_base) from
> [<c028c148>] (drm_crtc_helper_set_config+0x828/0x8a4)
> [  132.594329] [<c028c148>] (drm_crtc_helper_set_config) from
> [<c029ce1c>] (drm_mode_set_config_internal+0x58/0xc0)
> [  132.604478] [<c029ce1c>] (drm_mode_set_config_internal) from
> [<c029fe64>] (drm_mode_setcrtc+0x388/0x4ac)
> [  132.613933] [<c029fe64>] (drm_mode_setcrtc) from [<c0292cb4>]
> (drm_ioctl+0x270/0x44c)
> [  132.621741] [<c0292cb4>] (drm_ioctl) from [<c011302c>]
> (do_vfs_ioctl+0x4e4/0x5a0)
> [  132.629201] [<c011302c>] (do_vfs_ioctl) from [<c0113144>]
> (SyS_ioctl+0x5c/0x84)
> [  132.636489] [<c0113144>] (SyS_ioctl) from [<c000e380>]
> (ret_fast_syscall+0x0/0x30)
> [  132.644035] Code: e8bd4000 e1a05000 e1a04001 eb09d7dc (e595032c)
> [  132.650164] ---[ end trace 4bc5b9657975a179 ]---
> [  132.654749] Kernel panic - not syncing: Fatal exception
> [  132.659912] CPU3: stopping
> [  132.662600] CPU: 3 PID: 478 Comm: rs:main Q:Reg Tainted: G      D W
>     3.16.0-rc1+ #623
> [  132.670673] [<c00155b8>] (unwind_backtrace) from [<c001213c>]
> (show_stack+0x20/0x24)
> [  132.678392] [<c001213c>] (show_stack) from [<c05217d4>]
> (dump_stack+0x7c/0x98)
> [  132.685590] [<c05217d4>] (dump_stack) from [<c001409c>]
> (handle_IPI+0xd8/0x160)
> [  132.692876] [<c001409c>] (handle_IPI) from [<c0008688>]
> (gic_handle_irq+0x68/0x70)
> [  132.700423] [<c0008688>] (gic_handle_irq) from [<c0012cc0>]
> (__irq_svc+0x40/0x50)
> 
> Regards,
> Rahul Sharma.
> 
>>
>> Thanks,
>> Inki Dae
>>
>>>
>>> This crashes the system.
>>>
>>> Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
>>> ---
>>> This works fine but I am not confident on the correctness of the
>>> solution.
>>>
>>>  drivers/gpu/drm/exynos/exynos_drm_crtc.c |    6 ++++++
>>>  1 file changed, 6 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
>>> index 95c9435..da4efe4 100644
>>> --- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c
>>> +++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
>>> @@ -165,6 +165,12 @@ static int exynos_drm_crtc_mode_set_commit(struct drm_crtc *crtc, int x, int y,
>>>                 return -EPERM;
>>>         }
>>>
>>> +       /* when framebuffer is removed, commit should not proceed. */
>>> +       if(!plane->fb){
>>> +               DRM_ERROR("framebuffer has been removed from plane.\n");
>>> +               return -EFAULT;
>>> +       }
>>> +
>>>         crtc_w = crtc->primary->fb->width - x;
>>>         crtc_h = crtc->primary->fb->height - y;
>>>
>>> --
>>> 1.7.9.5
>>>
>>> --
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> 

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