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

[Gustavo A. R. Silva]

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_jjohn...@quicinc.com>

Reviewed-by: Gustavo A. R. Silva <gustavo...@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 {