Revert "Scm: Remove unnecessary pid & credential references in Unix socket's send...

This reverts commit 0856a304091b33a8e8f9f9c98e776f425af2b625.

As requested by Eric Dumazet, it has various ref-counting
problems and has introduced regressions.  Eric will add
a more suitable version of this performance fix.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/scm.h b/include/net/scm.h
index 68e1e48..745460f 100644 (file)
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -53,14 +53,6 @@ static __inline__ void scm_set_cred(struct scm_cookie *scm,
        cred_to_ucred(pid, cred, &scm->creds);
 }
 
-static __inline__ void scm_set_cred_noref(struct scm_cookie *scm,
-                                   struct pid *pid, const struct cred *cred)
-{
-       scm->pid  = pid;
-       scm->cred = cred;
-       cred_to_ucred(pid, cred, &scm->creds);
-}
-
 static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
 {
        put_pid(scm->pid);
@@ -78,15 +70,6 @@ static __inline__ void scm_destroy(struct scm_cookie *scm)
                __scm_destroy(scm);
 }
 
-static __inline__ void scm_release(struct scm_cookie *scm)
-{
-       /* keep ref on pid and cred */
-       scm->pid = NULL;
-       scm->cred = NULL;
-       if (scm->fp)
-               __scm_destroy(scm);
-}
-
 static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
                               struct scm_cookie *scm)
 {
@@ -125,14 +108,15 @@ static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
        if (!msg->msg_control) {
                if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp)
                        msg->msg_flags |= MSG_CTRUNC;
-               if (scm && scm->fp)
-                       __scm_destroy(scm);
+               scm_destroy(scm);
                return;
        }
 
        if (test_bit(SOCK_PASSCRED, &sock->flags))
                put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(scm->creds), &scm->creds);
 
+       scm_destroy_cred(scm);
+
        scm_passec(sock, msg, scm);
 
        if (!scm->fp)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index e6d9d10..ec68e1c 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1378,17 +1378,11 @@ static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
        return max_level;
 }
 
-static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb,
-                          bool send_fds, bool ref)
+static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
 {
        int err = 0;
-       if (ref) {
-               UNIXCB(skb).pid  = get_pid(scm->pid);
-               UNIXCB(skb).cred = get_cred(scm->cred);
-       } else {
-               UNIXCB(skb).pid  = scm->pid;
-               UNIXCB(skb).cred = scm->cred;
-       }
+       UNIXCB(skb).pid  = get_pid(scm->pid);
+       UNIXCB(skb).cred = get_cred(scm->cred);
        UNIXCB(skb).fp = NULL;
        if (scm->fp && send_fds)
                err = unix_attach_fds(scm, skb);
@@ -1413,7 +1407,7 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
        int namelen = 0; /* fake GCC */
        int err;
        unsigned hash;
-       struct sk_buff *skb = NULL;
+       struct sk_buff *skb;
        long timeo;
        struct scm_cookie tmp_scm;
        int max_level;
@@ -1454,7 +1448,7 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
        if (skb == NULL)
                goto out;
 
-       err = unix_scm_to_skb(siocb->scm, skb, true, false);
+       err = unix_scm_to_skb(siocb->scm, skb, true);
        if (err < 0)
                goto out_free;
        max_level = err + 1;
@@ -1550,7 +1544,7 @@ restart:
        unix_state_unlock(other);
        other->sk_data_ready(other, len);
        sock_put(other);
-       scm_release(siocb->scm);
+       scm_destroy(siocb->scm);
        return len;
 
 out_unlock:
@@ -1560,8 +1554,7 @@ out_free:
 out:
        if (other)
                sock_put(other);
-       if (skb == NULL)
-               scm_destroy(siocb->scm);
+       scm_destroy(siocb->scm);
        return err;
 }
 
@@ -1573,7 +1566,7 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
        struct sock *sk = sock->sk;
        struct sock *other = NULL;
        int err, size;
-       struct sk_buff *skb = NULL;
+       struct sk_buff *skb;
        int sent = 0;
        struct scm_cookie tmp_scm;
        bool fds_sent = false;
@@ -1638,11 +1631,11 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
                size = min_t(int, size, skb_tailroom(skb));
 
 
-               /* Only send the fds and no ref to pid in the first buffer */
-               err = unix_scm_to_skb(siocb->scm, skb, !fds_sent, fds_sent);
+               /* Only send the fds in the first buffer */
+               err = unix_scm_to_skb(siocb->scm, skb, !fds_sent);
                if (err < 0) {
                        kfree_skb(skb);
-                       goto out;
+                       goto out_err;
                }
                max_level = err + 1;
                fds_sent = true;
@@ -1650,7 +1643,7 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
                err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
                if (err) {
                        kfree_skb(skb);
-                       goto out;
+                       goto out_err;
                }
 
                unix_state_lock(other);
@@ -1667,10 +1660,7 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
                sent += size;
        }
 
-       if (skb)
-               scm_release(siocb->scm);
-       else
-               scm_destroy(siocb->scm);
+       scm_destroy(siocb->scm);
        siocb->scm = NULL;
 
        return sent;
@@ -1683,9 +1673,7 @@ pipe_err:
                send_sig(SIGPIPE, current, 0);
        err = -EPIPE;
 out_err:
-       if (skb == NULL)
-               scm_destroy(siocb->scm);
-out:
+       scm_destroy(siocb->scm);
        siocb->scm = NULL;
        return sent ? : err;
 }
@@ -1789,7 +1777,7 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
                siocb->scm = &tmp_scm;
                memset(&tmp_scm, 0, sizeof(tmp_scm));
        }
-       scm_set_cred_noref(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
+       scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
        unix_set_secdata(siocb->scm, skb);
 
        if (!(flags & MSG_PEEK)) {
@@ -1951,8 +1939,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
                        }
                } else {
                        /* Copy credentials */
-                       scm_set_cred_noref(siocb->scm, UNIXCB(skb).pid,
-                                          UNIXCB(skb).cred);
+                       scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
                        check_creds = 1;
                }