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Message-ID: <10a9a265-6910-807a-57c5-62ee41c731a5@collabora.com>
Date:   Wed, 20 Sep 2023 17:17:40 +0200
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Subject: Re: [PATCH v7 45/49] media: core: Add bitmap manage bufs array
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To:     Hans Verkuil <hverkuil-cisco@xs4all.nl>, mchehab@kernel.org,
        tfiga@chromium.org, m.szyprowski@samsung.com, ming.qian@nxp.com,
        ezequiel@vanguardiasur.com.ar, p.zabel@pengutronix.de,
        gregkh@linuxfoundation.org, nicolas.dufresne@collabora.com
Cc:     linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-arm-msm@vger.kernel.org,
        linux-rockchip@lists.infradead.org, linux-staging@lists.linux.dev,
        kernel@collabora.com
References: <20230914133323.198857-1-benjamin.gaignard@collabora.com>
 <20230914133323.198857-46-benjamin.gaignard@collabora.com>
 <1142bbb4-b8f1-44ec-962e-9347a231782f@xs4all.nl>
 <20b6b93e-eef8-3d7b-a3c2-795f220059d4@collabora.com>
 <470682b4-c14b-4237-bc46-fddfdd085026@xs4all.nl>
From:   Benjamin Gaignard <benjamin.gaignard@collabora.com>
In-Reply-To: <470682b4-c14b-4237-bc46-fddfdd085026@xs4all.nl>
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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 will add backtrace when doing test on v8

>
>
>>>> +
>>>> +    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.

I will change vb2_get_num_buffers() to inline function that solve the problem too.

>
> Regards,
>
> 	Hans
>