Commit 003c9410 authored Jan 12, 2017 by Shannon Nelson Committed by David S. Miller Jan 13, 2017

tcp: fix tcp_fastopen unaligned access complaints on sparc



Fix up a data alignment issue on sparc by swapping the order
of the cookie byte array field with the length field in
struct tcp_fastopen_cookie, and making it a proper union
to clean up the typecasting.

This addresses log complaints like these:
    log_unaligned: 113 callbacks suppressed
    Kernel unaligned access at TPC[976490] tcp_try_fastopen+0x2d0/0x360
    Kernel unaligned access at TPC[9764ac] tcp_try_fastopen+0x2ec/0x360
    Kernel unaligned access at TPC[9764c8] tcp_try_fastopen+0x308/0x360
    Kernel unaligned access at TPC[9764e4] tcp_try_fastopen+0x324/0x360
    Kernel unaligned access at TPC[976490] tcp_try_fastopen+0x2d0/0x360

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Shannon Nelson <shannon.nelson@oracle.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent fa79581e

include/linux/tcp.h

+6 −1

Original line number	Diff line number	Diff line
		@@ -62,8 +62,13 @@ static inline unsigned int tcp_optlen(const struct sk_buff *skb)

		/* TCP Fast Open Cookie as stored in memory */
		struct tcp_fastopen_cookie {
		s8 len;
		union {
		u8 val[TCP_FASTOPEN_COOKIE_MAX];
		#if IS_ENABLED(CONFIG_IPV6)
		struct in6_addr addr;
		#endif
		};
		s8 len;
		bool exp; /* In RFC6994 experimental option format */
		};

net/ipv4/tcp_fastopen.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -113,7 +113,7 @@ static bool tcp_fastopen_cookie_gen(struct request_sock *req,
		struct tcp_fastopen_cookie tmp;

		if (__tcp_fastopen_cookie_gen(&ip6h->saddr, &tmp)) {
		struct in6_addr buf = (struct in6_addr ) tmp.val;
		struct in6_addr *buf = &tmp.addr;
		int i;

		for (i = 0; i < 4; i++)