Message-ID: <035ae74b-5df5-493f-9835-02c1c30ccfcc@kernel.org>
Date: Thu, 3 Oct 2024 20:36:30 +0200
From: Danilo Krummrich <dakr@...nel.org>
To: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc: "Gustavo A. R. Silva" <gustavoars@...nel.org>,
 Karol Herbst <kherbst@...hat.com>, Lyude Paul <lyude@...hat.com>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH][next] drm/nouveau: Avoid -Wflex-array-member-not-at-end
 warning

On 9/13/24 12:23 PM, Danilo Krummrich wrote:
> Hi,
> 
> On 9/13/24 10:09 AM, Gustavo A. R. Silva wrote:
>> Hi all,
>>
>> Friendly ping: who can take this, please? 🙂
> 
> Usually, that's me. But I thought you might want to send a v2 based on Kees'
> comments?

Do you plan to follow up on this? I'd prefer if we could get rid of the open-
coded "17". So, maybe just go with the define until we have something like
STACK_FLEX_COUNT()?

> 
> - Danilo
> 
>>
>> Thanks
>> -Gustavo
>>
>> On 21/08/24 22:16, Gustavo A. R. Silva wrote:
>>> Use the `DEFINE_RAW_FLEX()` helper for an on-stack definition of
>>> a flexible structure where the size of the flexible-array member
>>> is known at compile-time, and refactor the rest of the code,
>>> accordingly.
>>>
>>> So, with this, fix the following warning:
>>>
>>> drivers/gpu/drm/nouveau/dispnv50/disp.c:779:47: warning: structure containing 
>>> a flexible array member is not at the end of another structure [-Wflex-array- 
>>> member-not-at-end]
>>>
>>> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
>>> ---
>>>   drivers/gpu/drm/nouveau/dispnv50/disp.c | 20 +++++++++-----------
>>>   1 file changed, 9 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/ 
>>> nouveau/dispnv50/disp.c
>>> index eed579a6c858..ddddc69640be 100644
>>> --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
>>> +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
>>> @@ -774,11 +774,9 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct 
>>> nouveau_crtc *nv_crtc,
>>>       struct drm_hdmi_info *hdmi = &nv_connector->base.display_info.hdmi;
>>>       union hdmi_infoframe infoframe = { 0 };
>>>       const u8 rekey = 56; /* binary driver, and tegra, constant */
>>> +    DEFINE_RAW_FLEX(struct nvif_outp_infoframe_v0, args, data, 17);
>>> +    const u8 data_len = 17; /* same length as in DEFINE_RAW_FLEX above. */
>>>       u32 max_ac_packet;
>>> -    struct {
>>> -        struct nvif_outp_infoframe_v0 infoframe;
>>> -        u8 data[17];
>>> -    } args = { 0 };
>>>       int ret, size;
>>>       max_ac_packet  = mode->htotal - mode->hdisplay;
>>> @@ -815,29 +813,29 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct 
>>> nouveau_crtc *nv_crtc,
>>>           return;
>>>       /* AVI InfoFrame. */
>>> -    args.infoframe.version = 0;
>>> -    args.infoframe.head = nv_crtc->index;
>>> +    args->version = 0;
>>> +    args->head = nv_crtc->index;
>>>       if (!drm_hdmi_avi_infoframe_from_display_mode(&infoframe.avi, 
>>> &nv_connector->base, mode)) {
>>>           drm_hdmi_avi_infoframe_quant_range(&infoframe.avi, &nv_connector- 
>>> >base, mode,
>>>                              HDMI_QUANTIZATION_RANGE_FULL);
>>> -        size = hdmi_infoframe_pack(&infoframe, args.data, 
>>> ARRAY_SIZE(args.data));
>>> +        size = hdmi_infoframe_pack(&infoframe, args->data, data_len);
>>>       } else {
>>>           size = 0;
>>>       }
>>> -    nvif_outp_infoframe(&nv_encoder->outp, NVIF_OUTP_INFOFRAME_V0_AVI, 
>>> &args.infoframe, size);
>>> +    nvif_outp_infoframe(&nv_encoder->outp, NVIF_OUTP_INFOFRAME_V0_AVI, args, 
>>> size);
>>>       /* Vendor InfoFrame. */
>>> -    memset(&args.data, 0, sizeof(args.data));
>>> +    memset(args->data, 0, data_len);
>>>       if (!drm_hdmi_vendor_infoframe_from_display_mode(&infoframe.vendor.hdmi,
>>>                                &nv_connector->base, mode))
>>> -        size = hdmi_infoframe_pack(&infoframe, args.data, 
>>> ARRAY_SIZE(args.data));
>>> +        size = hdmi_infoframe_pack(&infoframe, args->data, data_len);
>>>       else
>>>           size = 0;
>>> -    nvif_outp_infoframe(&nv_encoder->outp, NVIF_OUTP_INFOFRAME_V0_VSI, 
>>> &args.infoframe, size);
>>> +    nvif_outp_infoframe(&nv_encoder->outp, NVIF_OUTP_INFOFRAME_V0_VSI, args, 
>>> size);
>>>       nv_encoder->hdmi.enabled = true;
>>>   }
>>

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