[PATCH 1/3] [v2] sfc: add CONFIG_INET dependency for TC offload

[PATCH 1/3] [v2] sfc: add CONFIG_INET dependency for TC offload

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

The driver now fails to link when CONFIG_INET is disabled, so
add an explicit Kconfig dependency:

ld.lld: error: undefined symbol: ip_route_output_flow
>>> referenced by tc_encap_actions.c
>>>               drivers/net/ethernet/sfc/tc_encap_actions.o:(efx_tc_flower_create_encap_md) in archive vmlinux.a

ld.lld: error: undefined symbol: ip_send_check
>>> referenced by tc_encap_actions.c
>>>               drivers/net/ethernet/sfc/tc_encap_actions.o:(efx_gen_encap_header) in archive vmlinux.a
>>> referenced by tc_encap_actions.c
>>>               drivers/net/ethernet/sfc/tc_encap_actions.o:(efx_gen_encap_header) in archive vmlinux.a

ld.lld: error: undefined symbol: arp_tbl
>>> referenced by tc_encap_actions.c
>>>               drivers/net/ethernet/sfc/tc_encap_actions.o:(efx_tc_netevent_event) in archive vmlinux.a
>>> referenced by tc_encap_actions.c
>>>               drivers/net/ethernet/sfc/tc_encap_actions.o:(efx_tc_netevent_event) in archive vmlinux.a

Fixes: a1e82162af0b8 ("sfc: generate encap headers for TC offload")
Reviewed-by: Edward Cree <ecree.xilinx@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202306151656.yttECVTP-lkp@intel.com/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: add Fixes and Closes tags
---
 drivers/net/ethernet/sfc/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/sfc/Kconfig b/drivers/net/ethernet/sfc/Kconfig
index 4af36ba8906ba..3eb55dcfa8a61 100644
--- a/drivers/net/ethernet/sfc/Kconfig
+++ b/drivers/net/ethernet/sfc/Kconfig
@@ -50,6 +50,7 @@ config SFC_MCDI_MON
 config SFC_SRIOV
 	bool "Solarflare SFC9100-family SR-IOV support"
 	depends on SFC && PCI_IOV
+	depends on INET
 	default y
 	help
 	  This enables support for the Single Root I/O Virtualization
-- 
2.39.2

[PATCH 2/3] [v2] sfc: fix uninitialized variable use

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

The new efx_bind_neigh() function contains a broken code path when IPV6 is
disabled:

drivers/net/ethernet/sfc/tc_encap_actions.c:144:7: error: variable 'n' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
                if (encap->type & EFX_ENCAP_FLAG_IPV6) {
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc_encap_actions.c:184:8: note: uninitialized use occurs here
                if (!n) {
                     ^
drivers/net/ethernet/sfc/tc_encap_actions.c:144:3: note: remove the 'if' if its condition is always false
                if (encap->type & EFX_ENCAP_FLAG_IPV6) {
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc_encap_actions.c:141:22: note: initialize the variable 'n' to silence this warning
                struct neighbour *n;
                                   ^
                                    = NULL

Change it to use the existing error handling path here.

Fixes: 7e5e7d800011a ("sfc: neighbour lookup for TC encap action offload")
Suggested-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: use 'goto' instead of incorrectly entering another error path
---
 drivers/net/ethernet/sfc/tc_encap_actions.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/sfc/tc_encap_actions.c b/drivers/net/ethernet/sfc/tc_encap_actions.c
index aac259528e73e..7e8bcdb222ad1 100644
--- a/drivers/net/ethernet/sfc/tc_encap_actions.c
+++ b/drivers/net/ethernet/sfc/tc_encap_actions.c
@@ -164,6 +164,7 @@ static int efx_bind_neigh(struct efx_nic *efx,
 			 */
 			rc = -EOPNOTSUPP;
 			NL_SET_ERR_MSG_MOD(extack, "No IPv6 support (neigh bind)");
+			goto out_free;
 #endif
 		} else {
 			rt = ip_route_output_key(net, &flow4);
-- 
2.39.2

[PATCH 3/3] sfc: selftest: fix struct packing

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

Three of the sfc drivers define a packed loopback_payload structure with an
ethernet header followed by an IP header. However, the kernel definition
of iphdr specifies that this is 4-byte aligned, causing a W=1 warning:

net/ethernet/sfc/siena/selftest.c:46:15: error: field ip within 'struct efx_loopback_payload' is less aligned than 'struct iphdr' and is usually due to 'struct efx_loopback_payload' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
        struct iphdr ip;

As the iphdr packing is not easily changed without breaking other code,
change the three structures to use a local definition instead.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/ethernet/sfc/falcon/selftest.c | 21 ++++++++++++++++++++-
 drivers/net/ethernet/sfc/selftest.c        | 21 ++++++++++++++++++++-
 drivers/net/ethernet/sfc/siena/selftest.c  | 21 ++++++++++++++++++++-
 3 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/sfc/falcon/selftest.c b/drivers/net/ethernet/sfc/falcon/selftest.c
index 6a454ac6f8763..fb7fcd27a33a5 100644
--- a/drivers/net/ethernet/sfc/falcon/selftest.c
+++ b/drivers/net/ethernet/sfc/falcon/selftest.c
@@ -40,7 +40,26 @@
  */
 struct ef4_loopback_payload {
 	struct ethhdr header;
-	struct iphdr ip;
+	struct {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+		__u8	ihl:4,
+			version:4;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+		__u8	version:4,
+			ihl:4;
+#else
+#error	"Please fix <asm/byteorder.h>"
+#endif
+		__u8	tos;
+		__be16	tot_len;
+		__be16	id;
+		__be16	frag_off;
+		__u8	ttl;
+		__u8	protocol;
+		__sum16	check;
+		__be32	saddr;
+		__be32	daddr;
+	} __packed ip; /* unaligned struct iphdr */
 	struct udphdr udp;
 	__be16 iteration;
 	char msg[64];
diff --git a/drivers/net/ethernet/sfc/selftest.c b/drivers/net/ethernet/sfc/selftest.c
index 3c5227afd4977..440a57953779c 100644
--- a/drivers/net/ethernet/sfc/selftest.c
+++ b/drivers/net/ethernet/sfc/selftest.c
@@ -43,7 +43,26 @@
  */
 struct efx_loopback_payload {
 	struct ethhdr header;
-	struct iphdr ip;
+	struct {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+		__u8	ihl:4,
+			version:4;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+		__u8	version:4,
+			ihl:4;
+#else
+#error	"Please fix <asm/byteorder.h>"
+#endif
+		__u8	tos;
+		__be16	tot_len;
+		__be16	id;
+		__be16	frag_off;
+		__u8	ttl;
+		__u8	protocol;
+		__sum16	check;
+		__be32	saddr;
+		__be32	daddr;
+	} __packed ip; /* unaligned struct iphdr */
 	struct udphdr udp;
 	__be16 iteration;
 	char msg[64];
diff --git a/drivers/net/ethernet/sfc/siena/selftest.c b/drivers/net/ethernet/sfc/siena/selftest.c
index 07715a3d6beab..b8a8b0495f661 100644
--- a/drivers/net/ethernet/sfc/siena/selftest.c
+++ b/drivers/net/ethernet/sfc/siena/selftest.c
@@ -43,7 +43,26 @@
  */
 struct efx_loopback_payload {
 	struct ethhdr header;
-	struct iphdr ip;
+	struct {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+		__u8	ihl:4,
+			version:4;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+		__u8	version:4,
+			ihl:4;
+#else
+#error	"Please fix <asm/byteorder.h>"
+#endif
+		__u8	tos;
+		__be16	tot_len;
+		__be16	id;
+		__be16	frag_off;
+		__u8	ttl;
+		__u8	protocol;
+		__sum16	check;
+		__be32	saddr;
+		__be32	daddr;
+	} __packed ip; /* unaligned struct iphdr */
 	struct udphdr udp;
 	__be16 iteration;
 	char msg[64];
-- 
2.39.2

Re: [PATCH 1/3] [v2] sfc: add CONFIG_INET dependency for TC offload

[Edward Cree]

On 19/06/2023 10:12, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The driver now fails to link when CONFIG_INET is disabled, so
> add an explicit Kconfig dependency:
> 
> ld.lld: error: undefined symbol: ip_route_output_flow
>>>> referenced by tc_encap_actions.c
>>>>               drivers/net/ethernet/sfc/tc_encap_actions.o:(efx_tc_flower_create_encap_md) in archive vmlinux.a
> 
> ld.lld: error: undefined symbol: ip_send_check
>>>> referenced by tc_encap_actions.c
>>>>               drivers/net/ethernet/sfc/tc_encap_actions.o:(efx_gen_encap_header) in archive vmlinux.a
>>>> referenced by tc_encap_actions.c
>>>>               drivers/net/ethernet/sfc/tc_encap_actions.o:(efx_gen_encap_header) in archive vmlinux.a
> 
> ld.lld: error: undefined symbol: arp_tbl
>>>> referenced by tc_encap_actions.c
>>>>               drivers/net/ethernet/sfc/tc_encap_actions.o:(efx_tc_netevent_event) in archive vmlinux.a
>>>> referenced by tc_encap_actions.c
>>>>               drivers/net/ethernet/sfc/tc_encap_actions.o:(efx_tc_netevent_event) in archive vmlinux.a
> 
> Fixes: a1e82162af0b8 ("sfc: generate encap headers for TC offload")
> Reviewed-by: Edward Cree <ecree.xilinx@gmail.com>
> Reviewed-by: Simon Horman <simon.horman@corigine.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202306151656.yttECVTP-lkp@intel.com/
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Additionally
Fixes: 7e5e7d800011 ("sfc: neighbour lookup for TC encap action offload")

The subject line doesn't specify a target tree; this should be for net-next.

> ---
> v2: add Fixes and Closes tags
> ---
>  drivers/net/ethernet/sfc/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/ethernet/sfc/Kconfig b/drivers/net/ethernet/sfc/Kconfig
> index 4af36ba8906ba..3eb55dcfa8a61 100644
> --- a/drivers/net/ethernet/sfc/Kconfig
> +++ b/drivers/net/ethernet/sfc/Kconfig
> @@ -50,6 +50,7 @@ config SFC_MCDI_MON
>  config SFC_SRIOV
>  	bool "Solarflare SFC9100-family SR-IOV support"
>  	depends on SFC && PCI_IOV
> +	depends on INET
>  	default y
>  	help
>  	  This enables support for the Single Root I/O Virtualization
> 

Re: [PATCH 2/3] [v2] sfc: fix uninitialized variable use

[Edward Cree]

On 19/06/2023 10:12, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The new efx_bind_neigh() function contains a broken code path when IPV6 is
> disabled:
> 
> drivers/net/ethernet/sfc/tc_encap_actions.c:144:7: error: variable 'n' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
>                 if (encap->type & EFX_ENCAP_FLAG_IPV6) {
>                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/net/ethernet/sfc/tc_encap_actions.c:184:8: note: uninitialized use occurs here
>                 if (!n) {
>                      ^
> drivers/net/ethernet/sfc/tc_encap_actions.c:144:3: note: remove the 'if' if its condition is always false
>                 if (encap->type & EFX_ENCAP_FLAG_IPV6) {
>                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/net/ethernet/sfc/tc_encap_actions.c:141:22: note: initialize the variable 'n' to silence this warning
>                 struct neighbour *n;
>                                    ^
>                                     = NULL
> 
> Change it to use the existing error handling path here.
> 
> Fixes: 7e5e7d800011a ("sfc: neighbour lookup for TC encap action offload")
> Suggested-by: Edward Cree <ecree.xilinx@gmail.com>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Edward Cree <ecree.xilinx@gmail.com>

> ---
> v2: use 'goto' instead of incorrectly entering another error path
> ---
>  drivers/net/ethernet/sfc/tc_encap_actions.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/ethernet/sfc/tc_encap_actions.c b/drivers/net/ethernet/sfc/tc_encap_actions.c
> index aac259528e73e..7e8bcdb222ad1 100644
> --- a/drivers/net/ethernet/sfc/tc_encap_actions.c
> +++ b/drivers/net/ethernet/sfc/tc_encap_actions.c
> @@ -164,6 +164,7 @@ static int efx_bind_neigh(struct efx_nic *efx,
>  			 */
>  			rc = -EOPNOTSUPP;
>  			NL_SET_ERR_MSG_MOD(extack, "No IPv6 support (neigh bind)");
> +			goto out_free;
>  #endif
>  		} else {
>  			rt = ip_route_output_key(net, &flow4);
> 

Re: [PATCH 3/3] sfc: selftest: fix struct packing

[Edward Cree]

On 19/06/2023 10:12, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Three of the sfc drivers define a packed loopback_payload structure with an
> ethernet header followed by an IP header. However, the kernel definition
> of iphdr specifies that this is 4-byte aligned, causing a W=1 warning:
> 
> net/ethernet/sfc/siena/selftest.c:46:15: error: field ip within 'struct efx_loopback_payload' is less aligned than 'struct iphdr' and is usually due to 'struct efx_loopback_payload' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
>         struct iphdr ip;
> 
> As the iphdr packing is not easily changed without breaking other code,
> change the three structures to use a local definition instead.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Duplicating the definition isn't the prettiest thing in the world; it'd
 do for a quick fix if needed but I assume W=1 warnings aren't blocking
 anyone, so maybe defer this one for now and I'll follow up soon with a
 rewrite that fixes this more cleanly?  My idea is to drop the __packed
 from the containing struct, make efx_begin_loopback() copy the layers
 separately, and efx_loopback_rx_packet() similarly do something less
 direct than casting the packet data to the struct.

But I don't insist on it; if you want this fix in immediately then I'm
 okay with that too.

> ---
>  drivers/net/ethernet/sfc/falcon/selftest.c | 21 ++++++++++++++++++++-
>  drivers/net/ethernet/sfc/selftest.c        | 21 ++++++++++++++++++++-
>  drivers/net/ethernet/sfc/siena/selftest.c  | 21 ++++++++++++++++++++-
>  3 files changed, 60 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/sfc/falcon/selftest.c b/drivers/net/ethernet/sfc/falcon/selftest.c
> index 6a454ac6f8763..fb7fcd27a33a5 100644
> --- a/drivers/net/ethernet/sfc/falcon/selftest.c
> +++ b/drivers/net/ethernet/sfc/falcon/selftest.c
> @@ -40,7 +40,26 @@
>   */
>  struct ef4_loopback_payload {
>  	struct ethhdr header;
> -	struct iphdr ip;
> +	struct {
> +#if defined(__LITTLE_ENDIAN_BITFIELD)
> +		__u8	ihl:4,
> +			version:4;
> +#elif defined (__BIG_ENDIAN_BITFIELD)
> +		__u8	version:4,
> +			ihl:4;
> +#else
> +#error	"Please fix <asm/byteorder.h>"
> +#endif
> +		__u8	tos;
> +		__be16	tot_len;
> +		__be16	id;
> +		__be16	frag_off;
> +		__u8	ttl;
> +		__u8	protocol;
> +		__sum16	check;
> +		__be32	saddr;
> +		__be32	daddr;
> +	} __packed ip; /* unaligned struct iphdr */
>  	struct udphdr udp;
>  	__be16 iteration;
>  	char msg[64];
> diff --git a/drivers/net/ethernet/sfc/selftest.c b/drivers/net/ethernet/sfc/selftest.c
> index 3c5227afd4977..440a57953779c 100644
> --- a/drivers/net/ethernet/sfc/selftest.c
> +++ b/drivers/net/ethernet/sfc/selftest.c
> @@ -43,7 +43,26 @@
>   */
>  struct efx_loopback_payload {
>  	struct ethhdr header;
> -	struct iphdr ip;
> +	struct {
> +#if defined(__LITTLE_ENDIAN_BITFIELD)
> +		__u8	ihl:4,
> +			version:4;
> +#elif defined (__BIG_ENDIAN_BITFIELD)
> +		__u8	version:4,
> +			ihl:4;
> +#else
> +#error	"Please fix <asm/byteorder.h>"
> +#endif
> +		__u8	tos;
> +		__be16	tot_len;
> +		__be16	id;
> +		__be16	frag_off;
> +		__u8	ttl;
> +		__u8	protocol;
> +		__sum16	check;
> +		__be32	saddr;
> +		__be32	daddr;
> +	} __packed ip; /* unaligned struct iphdr */
>  	struct udphdr udp;
>  	__be16 iteration;
>  	char msg[64];
> diff --git a/drivers/net/ethernet/sfc/siena/selftest.c b/drivers/net/ethernet/sfc/siena/selftest.c
> index 07715a3d6beab..b8a8b0495f661 100644
> --- a/drivers/net/ethernet/sfc/siena/selftest.c
> +++ b/drivers/net/ethernet/sfc/siena/selftest.c
> @@ -43,7 +43,26 @@
>   */
>  struct efx_loopback_payload {
>  	struct ethhdr header;
> -	struct iphdr ip;
> +	struct {
> +#if defined(__LITTLE_ENDIAN_BITFIELD)
> +		__u8	ihl:4,
> +			version:4;
> +#elif defined (__BIG_ENDIAN_BITFIELD)
> +		__u8	version:4,
> +			ihl:4;
> +#else
> +#error	"Please fix <asm/byteorder.h>"
> +#endif
> +		__u8	tos;
> +		__be16	tot_len;
> +		__be16	id;
> +		__be16	frag_off;
> +		__u8	ttl;
> +		__u8	protocol;
> +		__sum16	check;
> +		__be32	saddr;
> +		__be32	daddr;
> +	} __packed ip; /* unaligned struct iphdr */
>  	struct udphdr udp;
>  	__be16 iteration;
>  	char msg[64];
> 

Re: [PATCH 3/3] sfc: selftest: fix struct packing

[Arnd Bergmann]

On Mon, Jun 19, 2023, at 12:25, Edward Cree wrote:
> On 19/06/2023 10:12, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@arndb.de>
>> 
>> Three of the sfc drivers define a packed loopback_payload structure with an
>> ethernet header followed by an IP header. However, the kernel definition
>> of iphdr specifies that this is 4-byte aligned, causing a W=1 warning:
>> 
>> net/ethernet/sfc/siena/selftest.c:46:15: error: field ip within 'struct efx_loopback_payload' is less aligned than 'struct iphdr' and is usually due to 'struct efx_loopback_payload' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
>>         struct iphdr ip;
>> 
>> As the iphdr packing is not easily changed without breaking other code,
>> change the three structures to use a local definition instead.
>> 
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> Duplicating the definition isn't the prettiest thing in the world; it'd
>  do for a quick fix if needed but I assume W=1 warnings aren't blocking
>  anyone, so maybe defer this one for now and I'll follow up soon with a
>  rewrite that fixes this more cleanly?  My idea is to drop the __packed
>  from the containing struct, make efx_begin_loopback() copy the layers
>  separately, and efx_loopback_rx_packet() similarly do something less
>  direct than casting the packet data to the struct.
>
> But I don't insist on it; if you want this fix in immediately then I'm
>  okay with that too.
>
>> ---
>>  drivers/net/ethernet/sfc/falcon/selftest.c | 21 ++++++++++++++++++++-
>>  drivers/net/ethernet/sfc/selftest.c        | 21 ++++++++++++++++++++-
>>  drivers/net/ethernet/sfc/siena/selftest.c  | 21 ++++++++++++++++++++-
>>  3 files changed, 60 insertions(+), 3 deletions(-)
>> 
>> diff --git a/drivers/net/ethernet/sfc/falcon/selftest.c b/drivers/net/ethernet/sfc/falcon/selftest.c
>> index 6a454ac6f8763..fb7fcd27a33a5 100644
>> --- a/drivers/net/ethernet/sfc/falcon/selftest.c
>> +++ b/drivers/net/ethernet/sfc/falcon/selftest.c
>> @@ -40,7 +40,26 @@
>>   */
>>  struct ef4_loopback_payload {
>>  	struct ethhdr header;
>> -	struct iphdr ip;
>> +	struct {
>> +#if defined(__LITTLE_ENDIAN_BITFIELD)
>> +		__u8	ihl:4,
>> +			version:4;
>> +#elif defined (__BIG_ENDIAN_BITFIELD)
>> +		__u8	version:4,
>> +			ihl:4;
>> +#else
>> +#error	"Please fix <asm/byteorder.h>"
>> +#endif
>> +		__u8	tos;
>> +		__be16	tot_len;
>> +		__be16	id;
>> +		__be16	frag_off;
>> +		__u8	ttl;
>> +		__u8	protocol;
>> +		__sum16	check;
>> +		__be32	saddr;
>> +		__be32	daddr;
>> +	} __packed ip; /* unaligned struct iphdr */
>>  	struct udphdr udp;
>>  	__be16 iteration;
>>  	char msg[64];
>> diff --git a/drivers/net/ethernet/sfc/selftest.c b/drivers/net/ethernet/sfc/selftest.c
>> index 3c5227afd4977..440a57953779c 100644
>> --- a/drivers/net/ethernet/sfc/selftest.c
>> +++ b/drivers/net/ethernet/sfc/selftest.c
>> @@ -43,7 +43,26 @@
>>   */
>>  struct efx_loopback_payload {
>>  	struct ethhdr header;
>> -	struct iphdr ip;
>> +	struct {
>> +#if defined(__LITTLE_ENDIAN_BITFIELD)
>> +		__u8	ihl:4,
>> +			version:4;
>> +#elif defined (__BIG_ENDIAN_BITFIELD)
>> +		__u8	version:4,
>> +			ihl:4;
>> +#else
>> +#error	"Please fix <asm/byteorder.h>"
>> +#endif
>> +		__u8	tos;
>> +		__be16	tot_len;
>> +		__be16	id;
>> +		__be16	frag_off;
>> +		__u8	ttl;
>> +		__u8	protocol;
>> +		__sum16	check;
>> +		__be32	saddr;
>> +		__be32	daddr;
>> +	} __packed ip; /* unaligned struct iphdr */
>>  	struct udphdr udp;
>>  	__be16 iteration;
>>  	char msg[64];
>> diff --git a/drivers/net/ethernet/sfc/siena/selftest.c b/drivers/net/ethernet/sfc/siena/selftest.c
>> index 07715a3d6beab..b8a8b0495f661 100644
>> --- a/drivers/net/ethernet/sfc/siena/selftest.c
>> +++ b/drivers/net/ethernet/sfc/siena/selftest.c
>> @@ -43,7 +43,26 @@
>>   */
>>  struct efx_loopback_payload {
>>  	struct ethhdr header;
>> -	struct iphdr ip;
>> +	struct {
>> +#if defined(__LITTLE_ENDIAN_BITFIELD)
>> +		__u8	ihl:4,
>> +			version:4;
>> +#elif defined (__BIG_ENDIAN_BITFIELD)
>> +		__u8	version:4,
>> +			ihl:4;
>> +#else
>> +#error	"Please fix <asm/byteorder.h>"
>> +#endif
>> +		__u8	tos;
>> +		__be16	tot_len;
>> +		__be16	id;
>> +		__be16	frag_off;
>> +		__u8	ttl;
>> +		__u8	protocol;
>> +		__sum16	check;
>> +		__be32	saddr;
>> +		__be32	daddr;
>> +	} __packed ip; /* unaligned struct iphdr */
>>  	struct udphdr udp;
>>  	__be16 iteration;
>>  	char msg[64];
>>

Re: [PATCH 3/3] sfc: selftest: fix struct packing

[Arnd Bergmann]

On Mon, Jun 19, 2023, at 12:25, Edward Cree wrote:
> On 19/06/2023 10:12, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@arndb.de>
>> 
>> Three of the sfc drivers define a packed loopback_payload structure with an
>> ethernet header followed by an IP header. However, the kernel definition
>> of iphdr specifies that this is 4-byte aligned, causing a W=1 warning:
>> 
>> net/ethernet/sfc/siena/selftest.c:46:15: error: field ip within 'struct efx_loopback_payload' is less aligned than 'struct iphdr' and is usually due to 'struct efx_loopback_payload' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
>>         struct iphdr ip;
>> 
>> As the iphdr packing is not easily changed without breaking other code,
>> change the three structures to use a local definition instead.
>> 
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> Duplicating the definition isn't the prettiest thing in the world; it'd
>  do for a quick fix if needed but I assume W=1 warnings aren't blocking
>  anyone, so maybe defer this one for now and I'll follow up soon with a
>  rewrite that fixes this more cleanly?  My idea is to drop the __packed
>  from the containing struct, make efx_begin_loopback() copy the layers
>  separately, and efx_loopback_rx_packet() similarly do something less
>  direct than casting the packet data to the struct.
>
> But I don't insist on it; if you want this fix in immediately then I'm
>  okay with that too.

It's not urgent, if you can come up with a nicer solution, that is
probably better than applying my patch now. I have a patch [1] that
addresses -Wunaligned-access for all x86 and arm randconfig builds,
and this currently affects 23 drivers. Most of the changes don't
have changelog texts yet, and some need a more detailed analysis to
come up with a correct patch. I'd probably aim for linux-6.6 or
later to get them all done, at which point we could move the warning
from W=1 to the default set.

     Arnd

[1] https://pastebin.com/g6D9NTS4

Re: [PATCH 1/3] [v2] sfc: add CONFIG_INET dependency for TC offload

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 19 Jun 2023 11:12:09 +0200 you wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The driver now fails to link when CONFIG_INET is disabled, so
> add an explicit Kconfig dependency:
> 
> ld.lld: error: undefined symbol: ip_route_output_flow
> >>> referenced by tc_encap_actions.c
> >>>               drivers/net/ethernet/sfc/tc_encap_actions.o:(efx_tc_flower_create_encap_md) in archive vmlinux.a
> 
> [...]

Here is the summary with links:
  - [1/3,v2] sfc: add CONFIG_INET dependency for TC offload
    https://git.kernel.org/netdev/net-next/c/40cba83370c2
  - [2/3,v2] sfc: fix uninitialized variable use
    https://git.kernel.org/netdev/net-next/c/f61d2d5cf142
  - [3/3] sfc: selftest: fix struct packing
    (no matching commit)

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

RE: [PATCH 3/3] sfc: selftest: fix struct packing

[David Laight]

...
> Duplicating the definition isn't the prettiest thing in the world; it'd
>  do for a quick fix if needed but I assume W=1 warnings aren't blocking
>  anyone, so maybe defer this one for now and I'll follow up soon with a
>  rewrite that fixes this more cleanly?  My idea is to drop the __packed
>  from the containing struct, make efx_begin_loopback() copy the layers
>  separately, and efx_loopback_rx_packet() similarly do something less
>  direct than casting the packet data to the struct.

Maybe you can get away with adding a 16bit pad before the ethernet
header so that the IP header is actually aligned.

(Then fight all the stuff that stops you doing a memcpy()
that runs into a second field of a structure.)

Failing that maybe a single shared copy of the misaligned
IP header.

I also suspect you could just add __packed to the two 32bit
address fields.
That would generate better code on systems that care.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

Re: [PATCH 3/3] sfc: selftest: fix struct packing

[Edward Cree]

On 23/06/2023 11:52, David Laight wrote:
> Maybe you can get away with adding a 16bit pad before the ethernet
> header so that the IP header is actually aligned.

That's what I ended up doing, because my original idea was
 overcomplicated and turned out super ugly.
See https://lore.kernel.org/netdev/6f87fdf5-1844-4633-b4fe-6b247bc6ab49@app.fastmail.com/T/

> (Then fight all the stuff that stops you doing a memcpy()
> that runs into a second field of a structure.)

Yeah, I don't know how you're meant to annotate that stuff.
I guess I'll have to wait until Kees shouts at me and tells
 me what to do :S

-ed