[PATCH][next] iwlegacy: Avoid multiple -Wflex-array-member-not-at-end warnings

[PATCH][next] iwlegacy: Avoid multiple -Wflex-array-member-not-at-end warnings

[Gustavo A. R. Silva]

-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.

Move the conflicting declarations (which in a couple of cases happens
to be in a union, so we're moving the entire unions) to the end of the
corresponding structures. Notice that `struct il_tx_beacon_cmd`,
`struct il4965_tx_resp`, and `struct il3945_tx_beacon_cmd` are flexible
structures, this is structures that contain a flexible-array member.

With these changes fix the following warnings:

11 drivers/net/wireless/intel/iwlegacy/common.h:526:11: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
11 drivers/net/wireless/intel/iwlegacy/commands.h:2667:31: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
4 drivers/net/wireless/intel/iwlegacy/3945.h:131:11: 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@kernel.org>
---
 drivers/net/wireless/intel/iwlegacy/3945.h     | 4 +++-
 drivers/net/wireless/intel/iwlegacy/commands.h | 4 +++-
 drivers/net/wireless/intel/iwlegacy/common.h   | 4 +++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlegacy/3945.h b/drivers/net/wireless/intel/iwlegacy/3945.h
index fb1e33c89d0e..ed63b31fee9a 100644
--- a/drivers/net/wireless/intel/iwlegacy/3945.h
+++ b/drivers/net/wireless/intel/iwlegacy/3945.h
@@ -123,13 +123,15 @@ enum il3945_antenna {
 #define IEEE80211_FRAME_LEN             (IEEE80211_DATA_LEN + IEEE80211_HLEN)
 
 struct il3945_frame {
+	struct list_head list;
+
+	/* Must be last as it ends in a flexible-array member. */
 	union {
 		struct ieee80211_hdr frame;
 		struct il3945_tx_beacon_cmd beacon;
 		u8 raw[IEEE80211_FRAME_LEN];
 		u8 cmd[360];
 	} u;
-	struct list_head list;
 };
 
 #define SUP_RATE_11A_MAX_NUM_CHANNELS  8
diff --git a/drivers/net/wireless/intel/iwlegacy/commands.h b/drivers/net/wireless/intel/iwlegacy/commands.h
index b61b8f377702..2e665072f6d3 100644
--- a/drivers/net/wireless/intel/iwlegacy/commands.h
+++ b/drivers/net/wireless/intel/iwlegacy/commands.h
@@ -2664,10 +2664,12 @@ struct il3945_beacon_notif {
 } __packed;
 
 struct il4965_beacon_notif {
-	struct il4965_tx_resp beacon_notify_hdr;
 	__le32 low_tsf;
 	__le32 high_tsf;
 	__le32 ibss_mgr_status;
+
+	/* Must be last as it ends in a flexible-array member. */
+	struct il4965_tx_resp beacon_notify_hdr;
 } __packed;
 
 /*
diff --git a/drivers/net/wireless/intel/iwlegacy/common.h b/drivers/net/wireless/intel/iwlegacy/common.h
index 4c9836ab11dd..21f1c7702add 100644
--- a/drivers/net/wireless/intel/iwlegacy/common.h
+++ b/drivers/net/wireless/intel/iwlegacy/common.h
@@ -518,13 +518,15 @@ struct il_channel_info {
 #define IEEE80211_FRAME_LEN             (IEEE80211_DATA_LEN + IEEE80211_HLEN)
 
 struct il_frame {
+	struct list_head list;
+
+	/* Must be last as it ends in a flexible-array member. */
 	union {
 		struct ieee80211_hdr frame;
 		struct il_tx_beacon_cmd beacon;
 		u8 raw[IEEE80211_FRAME_LEN];
 		u8 cmd[360];
 	} u;
-	struct list_head list;
 };
 
 enum {
-- 
2.43.0

Re: [PATCH][next] iwlegacy: Avoid multiple -Wflex-array-member-not-at-end warnings

[Johannes Berg]

On Wed, 2025-11-19 at 17:41 +0900, Gustavo A. R. Silva wrote:
> -Wflex-array-member-not-at-end was introduced in GCC-14, and we are
> getting ready to enable it, globally.

Look, I honor your noble goals, but ... it'd be useful if the code
actually worked after :)


> --- a/drivers/net/wireless/intel/iwlegacy/commands.h
> +++ b/drivers/net/wireless/intel/iwlegacy/commands.h
> @@ -2664,10 +2664,12 @@ struct il3945_beacon_notif {
>  } __packed;
>  
>  struct il4965_beacon_notif {
> -	struct il4965_tx_resp beacon_notify_hdr;
>  	__le32 low_tsf;
>  	__le32 high_tsf;
>  	__le32 ibss_mgr_status;
> +
> +	/* Must be last as it ends in a flexible-array member. */
> +	struct il4965_tx_resp beacon_notify_hdr;
>  } __packed;

You can't just randomly rearrange firmware API. The __packed and __le32
really ought to have given you a hint here.

johannes