forked from Minki/linux
tcp: pass back data left in socket after receive
This is currently done for CMSG_INQ, add an ability to do so via struct msghdr as well and have CMSG_INQ use that too. If the caller sets msghdr->msg_get_inq, then we'll pass back the hint in msghdr->msg_inq. Rearrange struct msghdr a bit so we can add this member while shrinking it at the same time. On a 64-bit build, it was 96 bytes before this change and 88 bytes afterwards. Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Link: https://lore.kernel.org/r/650c22ca-cffc-0255-9a05-2413a1e20826@kernel.dk Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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@ -50,6 +50,9 @@ struct linger {
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struct msghdr {
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void *msg_name; /* ptr to socket address structure */
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int msg_namelen; /* size of socket address structure */
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int msg_inq; /* output, data left in socket */
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struct iov_iter msg_iter; /* data */
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/*
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@ -62,8 +65,9 @@ struct msghdr {
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void __user *msg_control_user;
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};
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bool msg_control_is_user : 1;
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__kernel_size_t msg_controllen; /* ancillary data buffer length */
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bool msg_get_inq : 1;/* return INQ after receive */
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unsigned int msg_flags; /* flags on received message */
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__kernel_size_t msg_controllen; /* ancillary data buffer length */
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struct kiocb *msg_iocb; /* ptr to iocb for async requests */
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};
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@ -2335,8 +2335,10 @@ static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len,
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if (sk->sk_state == TCP_LISTEN)
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goto out;
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if (tp->recvmsg_inq)
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if (tp->recvmsg_inq) {
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*cmsg_flags = TCP_CMSG_INQ;
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msg->msg_get_inq = 1;
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}
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timeo = sock_rcvtimeo(sk, nonblock);
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/* Urgent data needs to be handled specially. */
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@ -2559,7 +2561,7 @@ recv_sndq:
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int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
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int flags, int *addr_len)
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{
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int cmsg_flags = 0, ret, inq;
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int cmsg_flags = 0, ret;
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struct scm_timestamping_internal tss;
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if (unlikely(flags & MSG_ERRQUEUE))
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@ -2576,12 +2578,14 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
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release_sock(sk);
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sk_defer_free_flush(sk);
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if (cmsg_flags && ret >= 0) {
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if ((cmsg_flags || msg->msg_get_inq) && ret >= 0) {
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if (cmsg_flags & TCP_CMSG_TS)
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tcp_recv_timestamp(msg, sk, &tss);
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if (cmsg_flags & TCP_CMSG_INQ) {
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inq = tcp_inq_hint(sk);
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put_cmsg(msg, SOL_TCP, TCP_CM_INQ, sizeof(inq), &inq);
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if (msg->msg_get_inq) {
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msg->msg_inq = tcp_inq_hint(sk);
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if (cmsg_flags & TCP_CMSG_INQ)
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put_cmsg(msg, SOL_TCP, TCP_CM_INQ,
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sizeof(msg->msg_inq), &msg->msg_inq);
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}
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}
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return ret;
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