linux-kernel - Re: [PATCH v2] media: mediatek: encoder: Fix uninitialized scalar variable issue

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Message-ID: <dbfac6888a2c77c302265df2f90bf4aec8bed686.camel@mediatek.com>
Date: Mon, 1 Sep 2025 02:37:23 +0000
From: Irui Wang (王瑞) <Irui.Wang@...iatek.com>
To: "rongqianfeng@...o.com" <rongqianfeng@...o.com>, "matthias.bgg@...il.com"
	<matthias.bgg@...il.com>, "mchehab@...nel.org" <mchehab@...nel.org>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	"nicolas.dufresne@...labora.com" <nicolas.dufresne@...labora.com>,
	"hverkuil-cisco@...all.nl" <hverkuil-cisco@...all.nl>
CC: "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-media@...r.kernel.org"
	<linux-media@...r.kernel.org>, "linux-mediatek@...ts.infradead.org"
	<linux-mediatek@...ts.infradead.org>,
	Longfei Wang (王龙飞) <Longfei.Wang@...iatek.com>,
	Project_Global_Chrome_Upstream_Group
	<Project_Global_Chrome_Upstream_Group@...iatek.com>,
	Yunfei Dong (董云飞) <Yunfei.Dong@...iatek.com>
Subject: Re: [PATCH v2] media: mediatek: encoder: Fix uninitialized scalar
 variable issue

Dear Nicolas,

Thanks for your comments.

On Fri, 2025-08-29 at 15:10 -0400, Nicolas Dufresne wrote:
> Le mercredi 16 juillet 2025 à 15:14 +0800, Irui Wang a écrit :
> > UNINIT checker finds some instances of variables that are used
> > without being initialized, for example using the uninitialized
> > value enc_result.is_key_frm can result in unpredictable behavior,
> > so initialize these variables after declaring.
> > 
> > Fixes: 4e855a6efa54 ("[media] vcodec: mediatek: Add Mediatek V4L2
> > Video
> > Encoder Driver")
> > 
> > Signed-off-by: Irui Wang <irui.wang@...iatek.com>
> > ---
> > v2:
> >  - Add Fixes tag, update commit message
> >  - Remove unnecessary memset
> >  - Move memset to before the first usage
> > ---
> >  .../media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc.c   | 4
> > +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git
> > a/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc.c
> > b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc.c
> > index a01dc25a7699..3065f3e66336 100644
> > ---
> > a/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc.c
> > +++
> > b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc.c
> > @@ -865,7 +865,7 @@ static void vb2ops_venc_buf_queue(struct
> > vb2_buffer *vb)
> >  static int vb2ops_venc_start_streaming(struct vb2_queue *q,
> > unsigned int
> > count)
> >  {
> >  	struct mtk_vcodec_enc_ctx *ctx = vb2_get_drv_priv(q);
> > -	struct venc_enc_param param;
> > +	struct venc_enc_param param = { 0 };
> >  	int ret;
> >  	int i;
> >  
> > @@ -1036,6 +1036,7 @@ static int mtk_venc_encode_header(void *priv)
> >  			  ctx->id, dst_buf->vb2_buf.index, bs_buf.va,
> >  			  (u64)bs_buf.dma_addr, bs_buf.size);
> >  
> > +	memset(&enc_result, 0, sizeof(enc_result));
> 
> Please, apply review comment to all occurrence, so same here.
> 
> >  	ret = venc_if_encode(ctx,
> >  			VENC_START_OPT_ENCODE_SEQUENCE_HEADER,
> >  			NULL, &bs_buf, &enc_result);
> > @@ -1185,6 +1186,7 @@ static void mtk_venc_worker(struct
> > work_struct *work)
> >  			  (u64)frm_buf.fb_addr[1].dma_addr,
> > frm_buf.fb_addr[1].size,
> >  			  (u64)frm_buf.fb_addr[2].dma_addr,
> > frm_buf.fb_addr[2].size);
> >  
> > +	memset(&enc_result, 0, sizeof(enc_result));
> 
> Same here.
> 
> >  	ret = venc_if_encode(ctx, VENC_START_OPT_ENCODE_FRAME,
> >  			     &frm_buf, &bs_buf, &enc_result);
> >  
> > 
> 
> 
> Would be nice to coordinate with Qianfeng Rong <rongqianfeng@...o.com
> > [0], he
> ported the entire driver to this initialization method, which is
> clearly the way
> to go.
> 
> - Patch 1 will port the driver to {} stack init
> - Patch 2 will add missing initializes
> 
> Consistency is key for this type of things since developer usually
> follow the
> surrounding style.

I have learned Qianfeng's patch and comments. I understand what you
mean is change my patch coding style to Qianfeng's, modify 'memset' to
'{}' for initialization, and amend Qianfeng's patch as patch-2, then
send this two patches together.

If I misunderstood your opinion, please correct me, thank you very
much.

Best Regards
> 
> regards
> Nicolas
> 
> [0] 
> https://patchwork.linuxtv.org/project/linux-media/patch/20250803135514.118892-1-rongqianfeng@vivo.com/