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Commit b9bb53f3 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by David S. Miller
Browse files

sock: convert sk_peek_offset functions to WRITE_ONCE 



Make the peek offset interface safe to use in lockless environments.
Use READ_ONCE and WRITE_ONCE to avoid race conditions between testing
and updating the peek offset.

Suggested-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e43d15c8

include/net/sock.h

+13 −11
Original line number Diff line number Diff line
@@ -459,26 +459,28 @@ struct sock { 


static inline int sk_peek_offset(struct sock *sk, int flags)

{

	if ((flags & MSG_PEEK) && (sk->sk_peek_off >= 0))

		return sk->sk_peek_off;

	else

	if (unlikely(flags & MSG_PEEK)) {

		s32 off = READ_ONCE(sk->sk_peek_off);

		if (off >= 0)

			return off;

	}



	return 0;

}



static inline void sk_peek_offset_bwd(struct sock *sk, int val)

{

	if (sk->sk_peek_off >= 0) {

		if (sk->sk_peek_off >= val)

			sk->sk_peek_off -= val;

		else

			sk->sk_peek_off = 0;

	s32 off = READ_ONCE(sk->sk_peek_off);



	if (unlikely(off >= 0)) {

		off = max_t(s32, off - val, 0);

		WRITE_ONCE(sk->sk_peek_off, off);

	}

}



static inline void sk_peek_offset_fwd(struct sock *sk, int val)

{

	if (sk->sk_peek_off >= 0)

		sk->sk_peek_off += val;

	sk_peek_offset_bwd(sk, -val);

}



/*