problem in tcp_v4_synq_add ?

[Viorel Canja, Softwin]

Hello all,

I was looking through the networking code in 2.6.1 kernel and it seems
to me there could be a problem in tcp_ipv4.c in function tcp_v4_synq_add :

904 static void tcp_v4_synq_add(struct sock *sk, struct open_request *req)
905 {
906         struct tcp_opt *tp = tcp_sk(sk);
907         struct tcp_listen_opt *lopt = tp->listen_opt;
908         u32 h = tcp_v4_synq_hash(req->af.v4_req.rmt_addr, req->rmt_port, lopt->hash_rnd);
909 
910         req->expires = jiffies + TCP_TIMEOUT_INIT;
911         req->retrans = 0;
912         req->sk = NULL;
913         req->dl_next = lopt->syn_table[h];
914 
915         write_lock(&tp->syn_wait_lock);
916         lopt->syn_table[h] = req;
917         write_unlock(&tp->syn_wait_lock);
918 
919         tcp_synq_added(sk);
920 }

Shouldn't  "write_lock(&tp->syn_wait_lock);" be moved before
"req->dl_next = lopt->syn_table[h];" to avoid a race condition ?

I am new to the linux kernel so it is likely that I am missing
something. What am I missing ?

Thanks in advance,
Viorel

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