From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
To: Qian Cai <cai@lca.pw>
Cc: vyasevich@gmail.com, nhorman@tuxdriver.com,
linux-sctp@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net/sctp: fix GCC8+ -Wpacked-not-aligned warnings
Date: Fri, 26 Jul 2019 18:30:45 -0300 [thread overview]
Message-ID: <20190726213045.GL6204@localhost.localdomain> (raw)
In-Reply-To: <1564174659-21211-1-git-send-email-cai@lca.pw>
On Fri, Jul 26, 2019 at 04:57:39PM -0400, Qian Cai wrote:
> There are a lot of those warnings with GCC8+ 64bit,
>
> In file included from ./include/linux/sctp.h:42,
> from net/core/skbuff.c:47:
> ./include/uapi/linux/sctp.h:395:1: warning: alignment 4 of 'struct
> sctp_paddr_change' is less than 8 [-Wpacked-not-aligned]
> } __attribute__((packed, aligned(4)));
> ^
> ./include/uapi/linux/sctp.h:728:1: warning: alignment 4 of 'struct
> sctp_setpeerprim' is less than 8 [-Wpacked-not-aligned]
> } __attribute__((packed, aligned(4)));
> ^
> ./include/uapi/linux/sctp.h:727:26: warning: 'sspp_addr' offset 4 in
> 'struct sctp_setpeerprim' isn't aligned to 8 [-Wpacked-not-aligned]
> struct sockaddr_storage sspp_addr;
> ^~~~~~~~~
> ./include/uapi/linux/sctp.h:741:1: warning: alignment 4 of 'struct
> sctp_prim' is less than 8 [-Wpacked-not-aligned]
> } __attribute__((packed, aligned(4)));
> ^
> ./include/uapi/linux/sctp.h:740:26: warning: 'ssp_addr' offset 4 in
> 'struct sctp_prim' isn't aligned to 8 [-Wpacked-not-aligned]
> struct sockaddr_storage ssp_addr;
> ^~~~~~~~
> ./include/uapi/linux/sctp.h:792:1: warning: alignment 4 of 'struct
> sctp_paddrparams' is less than 8 [-Wpacked-not-aligned]
> } __attribute__((packed, aligned(4)));
> ^
> ./include/uapi/linux/sctp.h:784:26: warning: 'spp_address' offset 4 in
> 'struct sctp_paddrparams' isn't aligned to 8 [-Wpacked-not-aligned]
> struct sockaddr_storage spp_address;
> ^~~~~~~~~~~
> ./include/uapi/linux/sctp.h:905:1: warning: alignment 4 of 'struct
> sctp_paddrinfo' is less than 8 [-Wpacked-not-aligned]
> } __attribute__((packed, aligned(4)));
> ^
> ./include/uapi/linux/sctp.h:899:26: warning: 'spinfo_address' offset 4
> in 'struct sctp_paddrinfo' isn't aligned to 8 [-Wpacked-not-aligned]
> struct sockaddr_storage spinfo_address;
> ^~~~~~~~~~~~~~
> Fix them by aligning the structures and fields to 8 bytes instead.
>
> Signed-off-by: Qian Cai <cai@lca.pw>
> ---
> include/uapi/linux/sctp.h | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
> index b8f2c4d56532..e7bd71cde882 100644
> --- a/include/uapi/linux/sctp.h
> +++ b/include/uapi/linux/sctp.h
These changes gotta be more careful, if possible at all. As is, it's breaking UAPI.
-before
+after patch
struct sctp_paddrparams {
sctp_assoc_t spp_assoc_id; /* 0 4 */
- struct __kernel_sockaddr_storage spp_address __attribute__((__aligned__(1))); /* 4 128 */
- /* --- cacheline 2 boundary (128 bytes) was 4 bytes ago --- */
- __u32 spp_hbinterval; /* 132 4 */
- __u16 spp_pathmaxrxt; /* 136 2 */
- __u32 spp_pathmtu; /* 138 4 */
- __u32 spp_sackdelay; /* 142 4 */
- __u32 spp_flags; /* 146 4 */
- __u32 spp_ipv6_flowlabel; /* 150 4 */
- __u8 spp_dscp; /* 154 1 */
- /* size: 156, cachelines: 3, members: 9 */
+ /* XXX 4 bytes hole, try to pack */
+
+ struct __kernel_sockaddr_storage spp_address __attribute__((__aligned__(8))); /* 8 128 */
+ /* --- cacheline 2 boundary (128 bytes) was 8 bytes ago --- */
+ __u32 spp_hbinterval; /* 136 4 */
+ __u16 spp_pathmaxrxt; /* 140 2 */
+ __u32 spp_pathmtu; /* 142 4 */
+ __u32 spp_sackdelay; /* 146 4 */
+ __u32 spp_flags; /* 150 4 */
+ __u32 spp_ipv6_flowlabel; /* 154 4 */
+ __u8 spp_dscp; /* 158 1 */
+
+ /* size: 160, cachelines: 3, members: 9 */
+ /* sum members: 155, holes: 1, sum holes: 4 */
/* padding: 1 */
- /* forced alignments: 1 */
- /* last cacheline: 28 bytes */
-} __attribute__((__aligned__(4)));
+ /* forced alignments: 1, forced holes: 1, sum forced holes: 4 */
+ /* last cacheline: 32 bytes */
+} __attribute__((__aligned__(8)));
> @@ -392,7 +392,7 @@ struct sctp_paddr_change {
> int spc_state;
> int spc_error;
> sctp_assoc_t spc_assoc_id;
> -} __attribute__((packed, aligned(4)));
> +} __attribute__((packed, aligned(8)));
>
> /*
> * spc_state: 32 bits (signed integer)
> @@ -724,8 +724,8 @@ struct sctp_assocparams {
> */
> struct sctp_setpeerprim {
> sctp_assoc_t sspp_assoc_id;
> - struct sockaddr_storage sspp_addr;
> -} __attribute__((packed, aligned(4)));
> + struct sockaddr_storage sspp_addr __attribute__((aligned(8)));
> +} __attribute__((packed, aligned(8)));
>
> /*
> * 7.1.10 Set Primary Address (SCTP_PRIMARY_ADDR)
> @@ -737,8 +737,8 @@ struct sctp_setpeerprim {
> */
> struct sctp_prim {
> sctp_assoc_t ssp_assoc_id;
> - struct sockaddr_storage ssp_addr;
> -} __attribute__((packed, aligned(4)));
> + struct sockaddr_storage ssp_addr __attribute__((aligned(8)));
> +} __attribute__((packed, aligned(8)));
>
> /* For backward compatibility use, define the old name too */
> #define sctp_setprim sctp_prim
> @@ -781,7 +781,7 @@ enum sctp_spp_flags {
>
> struct sctp_paddrparams {
> sctp_assoc_t spp_assoc_id;
> - struct sockaddr_storage spp_address;
> + struct sockaddr_storage spp_address __attribute__((aligned(8)));
> __u32 spp_hbinterval;
> __u16 spp_pathmaxrxt;
> __u32 spp_pathmtu;
> @@ -789,7 +789,7 @@ struct sctp_paddrparams {
> __u32 spp_flags;
> __u32 spp_ipv6_flowlabel;
> __u8 spp_dscp;
> -} __attribute__((packed, aligned(4)));
> +} __attribute__((packed, aligned(8)));
>
> /*
> * 7.1.18. Add a chunk that must be authenticated (SCTP_AUTH_CHUNK)
> @@ -896,13 +896,13 @@ struct sctp_stream_value {
> */
> struct sctp_paddrinfo {
> sctp_assoc_t spinfo_assoc_id;
> - struct sockaddr_storage spinfo_address;
> + struct sockaddr_storage spinfo_address __attribute__((aligned(8)));
> __s32 spinfo_state;
> __u32 spinfo_cwnd;
> __u32 spinfo_srtt;
> __u32 spinfo_rto;
> __u32 spinfo_mtu;
> -} __attribute__((packed, aligned(4)));
> +} __attribute__((packed, aligned(8)));
>
> /* Peer addresses's state. */
> /* UNKNOWN: Peer address passed by the upper layer in sendmsg or connect[x]
> --
> 1.8.3.1
>
next prev parent reply other threads:[~2019-07-26 21:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-26 20:57 [PATCH] net/sctp: fix GCC8+ -Wpacked-not-aligned warnings Qian Cai
2019-07-26 21:30 ` Marcelo Ricardo Leitner [this message]
2019-07-28 17:05 ` Qian Cai
2019-07-28 19:41 ` Marcelo Ricardo Leitner
2019-07-29 10:39 ` David Laight
2019-07-29 15:16 ` Qian Cai
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=20190726213045.GL6204@localhost.localdomain \
--to=marcelo.leitner@gmail.com \
--cc=cai@lca.pw \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-sctp@vger.kernel.org \
--cc=nhorman@tuxdriver.com \
--cc=vyasevich@gmail.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).