Commit e9d9da91 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: preserve const qualifier in tcp_sk() 



We can change tcp_sk() to propagate its argument const qualifier,
thanks to container_of_const().

We have two places where a const sock pointer has to be upgraded
to a write one. We have been using const qualifier for lockless
listeners to clearly identify points where writes could happen.

Add tcp_sk_rw() helper to better document these.

tcp_inbound_md5_hash(), __tcp_grow_window(), tcp_reset_check()
and tcp_rack_reo_wnd() get an additional const qualififer
for their @tp local variables.

smc_check_reset_syn_req() also needs a similar change.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarSimon Horman <simon.horman@corigine.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 403a40f2

include/linux/tcp.h

+6 −4
Original line number Diff line number Diff line
@@ -472,10 +472,12 @@ enum tsq_flags { 
	TCPF_MTU_REDUCED_DEFERRED	= (1UL << TCP_MTU_REDUCED_DEFERRED),

};



static inline struct tcp_sock *tcp_sk(const struct sock *sk)

{

	return (struct tcp_sock *)sk;

}

#define tcp_sk(ptr) container_of_const(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)



/* Variant of tcp_sk() upgrading a const sock to a read/write tcp socket.

 * Used in context of (lockless) tcp listeners.

 */

#define tcp_sk_rw(ptr) container_of(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)



struct tcp_timewait_sock {

	struct inet_timewait_sock tw_sk;

include/net/tcp.h

+1 −1
Original line number Diff line number Diff line
@@ -529,7 +529,7 @@ static inline void tcp_synq_overflow(const struct sock *sk) 


	last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);

	if (!time_between32(now, last_overflow, last_overflow + HZ))

		WRITE_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp, now);

		WRITE_ONCE(tcp_sk_rw(sk)->rx_opt.ts_recent_stamp, now);

}



/* syncookies: no recent synqueue overflow on this listening socket? */

net/ipv4/tcp.c

+1 −1
Original line number Diff line number Diff line
@@ -4570,7 +4570,7 @@ tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb, 
	const __u8 *hash_location = NULL;

	struct tcp_md5sig_key *hash_expected;

	const struct tcphdr *th = tcp_hdr(skb);

	struct tcp_sock *tp = tcp_sk(sk);

	const struct tcp_sock *tp = tcp_sk(sk);

	int genhash, l3index;

	u8 newhash[16];

net/ipv4/tcp_input.c

+2 −2
Original line number Diff line number Diff line
@@ -458,7 +458,7 @@ static void tcp_sndbuf_expand(struct sock *sk) 
static int __tcp_grow_window(const struct sock *sk, const struct sk_buff *skb,

			     unsigned int skbtruesize)

{

	struct tcp_sock *tp = tcp_sk(sk);

	const struct tcp_sock *tp = tcp_sk(sk);

	/* Optimize this! */

	int truesize = tcp_win_from_space(sk, skbtruesize) >> 1;

	int window = tcp_win_from_space(sk, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2])) >> 1;
@@ -5693,7 +5693,7 @@ static void tcp_urg(struct sock *sk, struct sk_buff *skb, const struct tcphdr *t 
 */

static bool tcp_reset_check(const struct sock *sk, const struct sk_buff *skb)

{

	struct tcp_sock *tp = tcp_sk(sk);

	const struct tcp_sock *tp = tcp_sk(sk);



	return unlikely(TCP_SKB_CB(skb)->seq == (tp->rcv_nxt - 1) &&

			(1 << sk->sk_state) & (TCPF_CLOSE_WAIT | TCPF_LAST_ACK |

net/ipv4/tcp_minisocks.c

+3 −2
Original line number Diff line number Diff line
@@ -463,7 +463,7 @@ void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst) 
}

EXPORT_SYMBOL_GPL(tcp_ca_openreq_child);



static void smc_check_reset_syn_req(struct tcp_sock *oldtp,

static void smc_check_reset_syn_req(const struct tcp_sock *oldtp,

				    struct request_sock *req,

				    struct tcp_sock *newtp)

{
@@ -492,7 +492,8 @@ struct sock *tcp_create_openreq_child(const struct sock *sk, 
	const struct inet_request_sock *ireq = inet_rsk(req);

	struct tcp_request_sock *treq = tcp_rsk(req);

	struct inet_connection_sock *newicsk;

	struct tcp_sock *oldtp, *newtp;

	const struct tcp_sock *oldtp;

	struct tcp_sock *newtp;

	u32 seq;



	if (!newsk)