linux-kernel - [PATCH 2/6] wifi: ath10k: use flexible arrays for WMI start scan TLVs

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Message-ID: <20231213-wmi_host_mem_chunks_flexarray-v1-2-92922d92fa2c@quicinc.com>
Date:   Wed, 13 Dec 2023 09:06:40 -0800
From:   Jeff Johnson <quic_jjohnson@...cinc.com>
To:     Kalle Valo <kvalo@...nel.org>,
        Jeff Johnson <quic_jjohnson@...cinc.com>
CC:     Kees Cook <keescook@...omium.org>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        <ath10k@...ts.infradead.org>, <linux-wireless@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/6] wifi: ath10k: use flexible arrays for WMI start scan
 TLVs

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@...cinc.com>
---
 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 {

-- 
2.42.0