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Message-ID: <708ed53c-181e-4149-b544-eaf0725d58fc@embeddedor.com>
Date: Wed, 13 Dec 2023 14:17:17 -0600
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Subject: Re: [PATCH 2/6] wifi: ath10k: use flexible arrays for WMI start scan
 TLVs
Content-Language: en-US
To: Jeff Johnson <quic_jjohnson@quicinc.com>, Kalle Valo <kvalo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>, ath10k@lists.infradead.org,
 linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20231213-wmi_host_mem_chunks_flexarray-v1-0-92922d92fa2c@quicinc.com>
 <20231213-wmi_host_mem_chunks_flexarray-v1-2-92922d92fa2c@quicinc.com>
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
In-Reply-To: <20231213-wmi_host_mem_chunks_flexarray-v1-2-92922d92fa2c@quicinc.com>
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On 12/13/23 11:06, Jeff Johnson wrote:
> Currently ath10k defines the following struct:
> 	struct wmi_start_scan_tlvs {
> 		u8 tlvs[0];
> 	} __packed;
> 
> Per the guidance in [1] this should be a flexible array. However, a
> direct replace to u8 tlvs[] results in the compilation error:
>         flexible array member in a struct with no named members
> 
> This is because C99 6.7.2.1 (16) requires that a structure containing
> a flexible array member must have more than one named member.
> 
> So rather than defining a separate struct wmi_start_scan_tlvs which
> contains the flexible tlvs[] array, just define the tlvs[] array where
> struct wmi_start_scan_tlvs is being used.
> 
> No functional changes, compile tested only.
> 
> [1] https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays
> 
> Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks!
--
Gustavo

> ---
>   drivers/net/wireless/ath/ath10k/wmi.c |  8 ++++----
>   drivers/net/wireless/ath/ath10k/wmi.h | 11 ++---------
>   2 files changed, 6 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath10k/wmi.c b/drivers/net/wireless/ath/ath10k/wmi.c
> index 88befe92f95d..4d5aadbc7159 100644
> --- a/drivers/net/wireless/ath/ath10k/wmi.c
> +++ b/drivers/net/wireless/ath/ath10k/wmi.c
> @@ -6927,14 +6927,14 @@ void ath10k_wmi_put_start_scan_common(struct wmi_start_scan_common *cmn,
>   }
>   
>   static void
> -ath10k_wmi_put_start_scan_tlvs(struct wmi_start_scan_tlvs *tlvs,
> +ath10k_wmi_put_start_scan_tlvs(u8 *tlvs,
>   			       const struct wmi_start_scan_arg *arg)
>   {
>   	struct wmi_ie_data *ie;
>   	struct wmi_chan_list *channels;
>   	struct wmi_ssid_list *ssids;
>   	struct wmi_bssid_list *bssids;
> -	void *ptr = tlvs->tlvs;
> +	void *ptr = tlvs;
>   	int i;
>   
>   	if (arg->n_channels) {
> @@ -7012,7 +7012,7 @@ ath10k_wmi_op_gen_start_scan(struct ath10k *ar,
>   	cmd = (struct wmi_start_scan_cmd *)skb->data;
>   
>   	ath10k_wmi_put_start_scan_common(&cmd->common, arg);
> -	ath10k_wmi_put_start_scan_tlvs(&cmd->tlvs, arg);
> +	ath10k_wmi_put_start_scan_tlvs(cmd->tlvs, arg);
>   
>   	cmd->burst_duration_ms = __cpu_to_le32(0);
>   
> @@ -7041,7 +7041,7 @@ ath10k_wmi_10x_op_gen_start_scan(struct ath10k *ar,
>   	cmd = (struct wmi_10x_start_scan_cmd *)skb->data;
>   
>   	ath10k_wmi_put_start_scan_common(&cmd->common, arg);
> -	ath10k_wmi_put_start_scan_tlvs(&cmd->tlvs, arg);
> +	ath10k_wmi_put_start_scan_tlvs(cmd->tlvs, arg);
>   
>   	ath10k_dbg(ar, ATH10K_DBG_WMI, "wmi 10x start scan\n");
>   	return skb;
> diff --git a/drivers/net/wireless/ath/ath10k/wmi.h b/drivers/net/wireless/ath/ath10k/wmi.h
> index 833ce0251a2c..52a409ff94e7 100644
> --- a/drivers/net/wireless/ath/ath10k/wmi.h
> +++ b/drivers/net/wireless/ath/ath10k/wmi.h
> @@ -3218,23 +3218,16 @@ struct wmi_start_scan_common {
>   	__le32 scan_ctrl_flags;
>   } __packed;
>   
> -struct wmi_start_scan_tlvs {
> -	/* TLV parameters. These includes channel list, ssid list, bssid list,
> -	 * extra ies.
> -	 */
> -	u8 tlvs[0];
> -} __packed;
> -
>   struct wmi_start_scan_cmd {
>   	struct wmi_start_scan_common common;
>   	__le32 burst_duration_ms;
> -	struct wmi_start_scan_tlvs tlvs;
> +	u8 tlvs[];
>   } __packed;
>   
>   /* This is the definition from 10.X firmware branch */
>   struct wmi_10x_start_scan_cmd {
>   	struct wmi_start_scan_common common;
> -	struct wmi_start_scan_tlvs tlvs;
> +	u8 tlvs[];
>   } __packed;
>   
>   struct wmi_ssid_arg {
>