From: Arnd Bergmann <[email protected]>
clang warns about an unpacked structure inside of a packed one:
drivers/net/wireless/broadcom/b43/b43.h:654:4: error: field data within 'struct b43_iv' is less aligned than 'union (unnamed union at /home/arnd/arm-soc/drivers/net/wireless/broadcom/b43/b43.h:651:2)' and is usually due to 'struct b43_iv' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
The problem here is that the anonymous union has the default alignment
from its members, apparently because the original author mixed up the
placement of the __packed attribute by placing it next to the struct
member rather than the union definition. As the struct itself is
also marked as __packed, there is no need to mark its members, so just
move the annotation to the inner type instead.
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/net/wireless/broadcom/b43/b43.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wireless/broadcom/b43/b43.h b/drivers/net/wireless/broadcom/b43/b43.h
index 9fc7c088a539..67b4bac048e5 100644
--- a/drivers/net/wireless/broadcom/b43/b43.h
+++ b/drivers/net/wireless/broadcom/b43/b43.h
@@ -651,7 +651,7 @@ struct b43_iv {
union {
__be16 d16;
__be32 d32;
- } data __packed;
+ } __packed data;
} __packed;
--
2.39.2
On Tue, May 16, 2023 at 09:45:42AM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> clang warns about an unpacked structure inside of a packed one:
>
> drivers/net/wireless/broadcom/b43/b43.h:654:4: error: field data within 'struct b43_iv' is less aligned than 'union (unnamed union at /home/arnd/arm-soc/drivers/net/wireless/broadcom/b43/b43.h:651:2)' and is usually due to 'struct b43_iv' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
>
> The problem here is that the anonymous union has the default alignment
> from its members, apparently because the original author mixed up the
> placement of the __packed attribute by placing it next to the struct
> member rather than the union definition. As the struct itself is
> also marked as __packed, there is no need to mark its members, so just
> move the annotation to the inner type instead.
>
> Signed-off-by: Arnd Bergmann <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
On Tue, 16 May 2023 09:45:42 +0200
Arnd Bergmann <[email protected]> wrote:
> b43_iv { union {
> __be16 d16;
> __be32 d32;
> - } data __packed;
> + } __packed data;
> } __packed;
>
>
Oh, interesting. This has probably been there forever.
Did you check if the b43legacy driver has the same issue?
Acked-by: Michael Büsch <[email protected]>
--
Michael Büsch
https://bues.ch/
On Tue, May 16, 2023, at 19:12, Michael Büsch wrote:
> On Tue, 16 May 2023 09:45:42 +0200
> Arnd Bergmann <[email protected]> wrote:
>
>> b43_iv { union {
>> __be16 d16;
>> __be32 d32;
>> - } data __packed;
>> + } __packed data;
>> } __packed;
>>
>>
>
> Oh, interesting. This has probably been there forever.
> Did you check if the b43legacy driver has the same issue?
I had not checked, but I see that it does have the same bug.
I only sent this one because the build bot (incorrectly)
blamed one of my recent patches for a regression here.
Which reminds me that I was missing:
Reported-by: kernel test robot <[email protected]>
Link: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Should I resend this as a combined patch for both drivers?
Arnd
On Tue, 16 May 2023 19:45:16 +0200
"Arnd Bergmann" <[email protected]> wrote:
> Should I resend this as a combined patch for both drivers?
I think that would be fine, yes.
Thank you for checking.
--
Michael Büsch
https://bues.ch/
On 5/16/23 02:45, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> clang warns about an unpacked structure inside of a packed one:
>
> drivers/net/wireless/broadcom/b43/b43.h:654:4: error: field data within 'struct b43_iv' is less aligned than 'union (unnamed union at /home/arnd/arm-soc/drivers/net/wireless/broadcom/b43/b43.h:651:2)' and is usually due to 'struct b43_iv' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
>
> The problem here is that the anonymous union has the default alignment
> from its members, apparently because the original author mixed up the
> placement of the __packed attribute by placing it next to the struct
> member rather than the union definition. As the struct itself is
> also marked as __packed, there is no need to mark its members, so just
> move the annotation to the inner type instead.
>
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> drivers/net/wireless/broadcom/b43/b43.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/broadcom/b43/b43.h b/drivers/net/wireless/broadcom/b43/b43.h
> index 9fc7c088a539..67b4bac048e5 100644
> --- a/drivers/net/wireless/broadcom/b43/b43.h
> +++ b/drivers/net/wireless/broadcom/b43/b43.h
> @@ -651,7 +651,7 @@ struct b43_iv {
> union {
> __be16 d16;
> __be32 d32;
> - } data __packed;
> + } __packed data > } __packed;
This change works on a BCM4306 and BCM4318=.
Tested-by: Larry Finger <[email protected]>
To answer Michael's question, b43legacy has the same issue.
Larry
Larry