[PATCH] ath10k: improve structure padding

[PATCH] ath10k: improve structure padding

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

Including an aligned structure inside of a packed one is ambiguous
and can lead to misaligned data, as pointed out by this clang warning:

drivers/net/wireless/ath/ath10k/htt.h:715:34: error: field prefix within 'struct htt_rx_indication' is less aligned than 'struct htt_rx_indication_prefix' and is usually due to 'struct htt_rx_indication' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
        struct htt_rx_indication_prefix prefix;
                                        ^
drivers/net/wireless/ath/ath10k/htt.h:736:34: error: field prefix within 'struct htt_rx_indication_hl' is less aligned than 'struct htt_rx_indication_prefix' and is usually due to 'struct htt_rx_indication_hl' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
        struct htt_rx_indication_prefix prefix;
                                        ^
drivers/net/wireless/ath/ath10k/htt.h:1564:2: error: field  within 'struct htt_tx_fetch_ind' is less aligned than 'union htt_tx_fetch_ind::(anonymous at drivers/net/wireless/ath/ath10k/htt.h:1564:2)' and is usually due to 'struct htt_tx_fetch_ind' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
        union {
        ^
drivers/net/wireless/ath/ath10k/htt.h:1702:2: error: field  within 'struct htt_resp' is less aligned than 'union htt_resp::(anonymous at drivers/net/wireless/ath/ath10k/htt.h:1702:2)' and is usually due to 'struct htt_resp' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]

These structures appear to actually need the packing since they
are embedded at misaligned offsets. Add even more such annotations
here to enforce bytewise access throughout the driver.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/wireless/ath/ath10k/htt.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/htt.h b/drivers/net/wireless/ath/ath10k/htt.h
index c051a22fce145..e0c9f45e74761 100644
--- a/drivers/net/wireless/ath/ath10k/htt.h
+++ b/drivers/net/wireless/ath/ath10k/htt.h
@@ -707,7 +707,7 @@ struct htt_rx_indication_prefix {
 	__le16 fw_rx_desc_bytes;
 	u8 pad0;
 	u8 pad1;
-};
+} __packed;
 
 struct htt_rx_indication {
 	struct htt_rx_indication_hdr hdr;
@@ -1565,7 +1565,7 @@ struct htt_tx_fetch_ind {
 		/* ath10k_htt_get_tx_fetch_ind_resp_ids() */
 		DECLARE_FLEX_ARRAY(__le32, resp_ids);
 		DECLARE_FLEX_ARRAY(struct htt_tx_fetch_record, records);
-	};
+	} __packed;
 } __packed;
 
 static inline void *
@@ -1723,7 +1723,7 @@ struct htt_resp {
 		struct htt_tx_mode_switch_ind tx_mode_switch_ind;
 		struct htt_channel_change chan_change;
 		struct htt_peer_tx_stats peer_tx_stats;
-	};
+	} __packed;
 } __packed;
 
 /*** host side structures follow ***/
-- 
2.39.2

Re: [PATCH] ath10k: improve structure padding

[Kalle Valo]

Arnd Bergmann <arnd@kernel.org> wrote:

> Including an aligned structure inside of a packed one is ambiguous
> and can lead to misaligned data, as pointed out by this clang warning:
> 
> drivers/net/wireless/ath/ath10k/htt.h:715:34: error: field prefix within 'struct htt_rx_indication' is less aligned than 'struct htt_rx_indication_prefix' and is usually due to 'struct htt_rx_indication' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
>         struct htt_rx_indication_prefix prefix;
>                                         ^
> drivers/net/wireless/ath/ath10k/htt.h:736:34: error: field prefix within 'struct htt_rx_indication_hl' is less aligned than 'struct htt_rx_indication_prefix' and is usually due to 'struct htt_rx_indication_hl' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
>         struct htt_rx_indication_prefix prefix;
>                                         ^
> drivers/net/wireless/ath/ath10k/htt.h:1564:2: error: field  within 'struct htt_tx_fetch_ind' is less aligned than 'union htt_tx_fetch_ind::(anonymous at drivers/net/wireless/ath/ath10k/htt.h:1564:2)' and is usually due to 'struct htt_tx_fetch_ind' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
>         union {
>         ^
> drivers/net/wireless/ath/ath10k/htt.h:1702:2: error: field  within 'struct htt_resp' is less aligned than 'union htt_resp::(anonymous at drivers/net/wireless/ath/ath10k/htt.h:1702:2)' and is usually due to 'struct htt_resp' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
> 
> These structures appear to actually need the packing since they
> are embedded at misaligned offsets. Add even more such annotations
> here to enforce bytewise access throughout the driver.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>

Patch applied to ath-next branch of ath.git, thanks.

12ec37be3faf wifi: ath10k: improve structure padding

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20230616090439.2484857-1-arnd@kernel.org/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches