On 21/09/2023 11:28, Benjamin Gaignard wrote:
>
> Le 20/09/2023 à 16:56, Hans Verkuil a écrit :
>> On 20/09/2023 16:30, Benjamin Gaignard wrote:
>> <snip>
>>
>>>>> num_buffers = min_t(unsigned int, num_buffers,
>>>>> q->max_allowed_buffers - vb2_get_num_buffers(q));
>>>>> - first_index = vb2_get_num_buffers(q);
>>>>> + first_index = bitmap_find_next_zero_area(q->bufs_map, q->max_allowed_buffers,
>>>>> + 0, num_buffers, 0);
>>>>> if (first_index >= q->max_allowed_buffers)
>>>>> return 0;
>>>>> @@ -675,7 +678,13 @@ static void __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
>>>>> struct vb2_buffer *vb2_get_buffer(struct vb2_queue *q, unsigned int index)
>>>>> {
>>>>> - if (index < q->num_buffers)
>>>>> + if (!q->bufs_map || !q->bufs)
>>>>> + return NULL;
>>>> I don't think this can ever happen.
>>> I got kernel crash without them.
>>> I will keep them.
>> What is the backtrace? How can this happen? It feels wrong that this can be
>> called with a vb2_queue that apparently is not properly initialized.
>
> I have this log when adding dump_stack() in vb2_get_buffer() if !q->bufs_bitmap:
>
> [ 18.924627] Call trace:
> [ 18.927090] dump_backtrace+0x94/0xec
> [ 18.930787] show_stack+0x18/0x24
> [ 18.934137] dump_stack_lvl+0x48/0x60
> [ 18.937833] dump_stack+0x18/0x24
> [ 18.941166] __vb2_queue_cancel+0x23c/0x2f0
> [ 18.945365] vb2_core_queue_release+0x24/0x6c
> [ 18.949740] vb2_queue_release+0x10/0x1c
> [ 18.953677] v4l2_m2m_ctx_release+0x20/0x40
> [ 18.957892] hantro_release+0x20/0x54
> [ 18.961584] v4l2_release+0x74/0xec
> [ 18.965110] __fput+0xb4/0x274
> [ 18.968205] __fput_sync+0x50/0x5c
> [ 18.971626] __arm64_sys_close+0x38/0x7c
> [ 18.975562] invoke_syscall+0x48/0x114
> [ 18.979329] el0_svc_common.constprop.0+0xc0/0xe0
> [ 18.984068] do_el0_svc+0x1c/0x28
> [ 18.987402] el0_svc+0x40/0xe8
> [ 18.990470] el0t_64_sync_handler+0x100/0x12c
> [ 18.994842] el0t_64_sync+0x190/0x194
>
> This happen at boot time when hantro driver is open and close without other actions.
Ah, now I see the problem. q->bufs and q->bufs_map are allocated in
vb2_core_create_bufs and vb2_core_reqbufs, but they should be allocated
in vb2_queue_init: that's the counterpart of vb2_core_queue_release.
With that change you shouldn't have to check for q->bufs/bufs_map anymore.
Regards,
Hans
>
>>
>>>>> +
>>>>> + return (bitmap_weight(q->bufs_map, q->max_allowed_buffers) > 0);
>>>> How about:
>>>>
>>>> return vb2_get_num_buffers(q) > 0;
>>> vb2_get_num_buffers is defined in videobuf2-core.c, I'm not sure that
>>> an inline function could depend of a module function.
>> Not a problem. E.g. v4l2-ctrls.h is full of such static inlines.
>>
>> Regards,
>>
>> Hans
>>
