Commit 02ab0d13 authored Dec 08, 2016 by Eric Dumazet Committed by David S. Miller Dec 09, 2016

udp: udp_rmem_release() should touch sk_rmem_alloc later



In flood situations, keeping sk_rmem_alloc at a high value
prevents producers from touching the socket.

It makes sense to lower sk_rmem_alloc only at the end
of udp_rmem_release() after the thread draining receive
queue in udp_recvmsg() finished the writes to sk_forward_alloc.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 6b229cf7

net/ipv4/udp.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1191,13 +1191,14 @@ static void udp_rmem_release(struct sock *sk, int size, int partial)
		}
		up->forward_deficit = 0;

		atomic_sub(size, &sk->sk_rmem_alloc);
		sk->sk_forward_alloc += size;
		amt = (sk->sk_forward_alloc - partial) & ~(SK_MEM_QUANTUM - 1);
		sk->sk_forward_alloc -= amt;

		if (amt)
		__sk_mem_reduce_allocated(sk, amt >> SK_MEM_QUANTUM_SHIFT);

		atomic_sub(size, &sk->sk_rmem_alloc);
		}

		/* Note: called with sk_receive_queue.lock held.

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