tcp: add const to tcp_try_rmem_schedule() and sk_rmem_schedule() skb

These functions to not modify the skb, add a const qualifier.

Signed-off-by: Eric Dumazet <[email protected]>
Reviewed-by: Kuniyuki Iwashima <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: edumazet

include/net/sock.h

@@ -1553,7 +1553,7 @@ __sk_rmem_schedule(struct sock *sk, int size, bool pfmemalloc)
 }
 
 static inline bool
-sk_rmem_schedule(struct sock *sk, struct sk_buff *skb, int size)
+sk_rmem_schedule(struct sock *sk, const struct sk_buff *skb, int size)
 {
 	return __sk_rmem_schedule(sk, size, skb_pfmemalloc(skb));
 }

net/ipv4/tcp_input.c

@@ -4888,7 +4888,7 @@ static void tcp_ofo_queue(struct sock *sk)
 static bool tcp_prune_ofo_queue(struct sock *sk, const struct sk_buff *in_skb);
 static int tcp_prune_queue(struct sock *sk, const struct sk_buff *in_skb);
 
-static int tcp_try_rmem_schedule(struct sock *sk, struct sk_buff *skb,
+static int tcp_try_rmem_schedule(struct sock *sk, const struct sk_buff *skb,
 				 unsigned int size)
 {
 	if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||