From: "Arnd Bergmann" <arnd@arndb.de>
To: "Edward Cree" <ecree.xilinx@gmail.com>,
"Arnd Bergmann" <arnd@kernel.org>,
"Martin Habets" <habetsm.xilinx@gmail.com>,
"David S . Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>
Cc: Netdev <netdev@vger.kernel.org>,
linux-net-drivers@amd.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] sfc: selftest: fix struct packing
Date: Mon, 19 Jun 2023 15:04:10 +0200 [thread overview]
Message-ID: <e3e9f246-5bf7-4868-aedb-0e194f52de5b@app.fastmail.com> (raw)
In-Reply-To: <7c448f02-4031-0a90-97e2-0cc663b0cff9@gmail.com>
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];
>>
next prev parent reply other threads:[~2023-06-19 13:04 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-19 9:12 [PATCH 1/3] [v2] sfc: add CONFIG_INET dependency for TC offload Arnd Bergmann
2023-06-19 9:12 ` [PATCH 2/3] [v2] sfc: fix uninitialized variable use Arnd Bergmann
2023-06-19 10:06 ` Edward Cree
2023-06-19 9:12 ` [PATCH 3/3] sfc: selftest: fix struct packing Arnd Bergmann
2023-06-19 10:25 ` Edward Cree
2023-06-19 13:04 ` Arnd Bergmann [this message]
2023-06-19 14:55 ` Arnd Bergmann
2023-06-23 10:52 ` David Laight
2023-06-23 12:57 ` Edward Cree
2023-06-19 10:04 ` [PATCH 1/3] [v2] sfc: add CONFIG_INET dependency for TC offload Edward Cree
2023-06-21 3:40 ` patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=e3e9f246-5bf7-4868-aedb-0e194f52de5b@app.fastmail.com \
--to=arnd@arndb.de \
--cc=arnd@kernel.org \
--cc=davem@davemloft.net \
--cc=ecree.xilinx@gmail.com \
--cc=edumazet@google.com \
--cc=habetsm.xilinx@gmail.com \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-net-drivers@amd.com \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).