net: remove sock_iocb

The sock_iocb structure is allocate on stack for each read/write-like
operation on sockets, and contains various fields of which only the
embedded msghdr and sometimes a pointer to the scm_cookie is ever used.
Get rid of the sock_iocb and put a msghdr directly on the stack and pass
the scm_cookie explicitly to netlink_mmap_sendmsg.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 43 insertions, 126 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 2210fec65669..15341499786c 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1374,29 +1374,6 @@ void sk_prot_clear_portaddr_nulls(struct sock *sk, int size);
 #define SOCK_BINDADDR_LOCK      4
 #define SOCK_BINDPORT_LOCK      8
 
-/* sock_iocb: used to kick off async processing of socket ios */
-struct sock_iocb {
-        struct list_head        list;
-
-        int                     flags;
-        int                     size;
-        struct socket           *sock;
-        struct sock             *sk;
-        struct scm_cookie       *scm;
-        struct msghdr           *msg, async_msg;
-        struct kiocb            *kiocb;
-};
-
-static inline struct sock_iocb *kiocb_to_siocb(struct kiocb *iocb)
-{
-        return (struct sock_iocb *)iocb->private;
-}
-
-static inline struct kiocb *siocb_to_kiocb(struct sock_iocb *si)
-{
-        return si->kiocb;
-}
-
 struct socket_alloc {
         struct socket socket;
         struct inode vfs_inode;
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 2197af00673a..a36777b7cfb6 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -695,7 +695,7 @@ static void netlink_ring_setup_skb(struct sk_buff *skb, struct sock *sk,
 
 static int netlink_mmap_sendmsg(struct sock *sk, struct msghdr *msg,
                                 u32 dst_portid, u32 dst_group,
-                                struct sock_iocb *siocb)
+                                struct scm_cookie *scm)
 {
         struct netlink_sock *nlk = nlk_sk(sk);
         struct netlink_ring *ring;
@@ -741,7 +741,7 @@ static int netlink_mmap_sendmsg(struct sock *sk, struct msghdr *msg,
 
                 NETLINK_CB(skb).portid    = nlk->portid;
                 NETLINK_CB(skb).dst_group = dst_group;
-                NETLINK_CB(skb).creds     = siocb->scm->creds;
+                NETLINK_CB(skb).creds     = scm->creds;
 
                 err = security_netlink_send(sk, skb);
                 if (err) {
@@ -820,7 +820,7 @@ static void netlink_ring_set_copied(struct sock *sk, struct sk_buff *skb)
 #define netlink_tx_is_mmaped(sk)        false
 #define netlink_mmap                    sock_no_mmap
 #define netlink_poll                    datagram_poll
-#define netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group, siocb)     0
+#define netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group, scm)       0
 #endif /* CONFIG_NETLINK_MMAP */
 
 static void netlink_skb_destructor(struct sk_buff *skb)
@@ -2259,7 +2259,6 @@ static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
 static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
                            struct msghdr *msg, size_t len)
 {
-        struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
         struct sock *sk = sock->sk;
         struct netlink_sock *nlk = nlk_sk(sk);
         DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
@@ -2273,10 +2272,7 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
         if (msg->msg_flags&MSG_OOB)
                 return -EOPNOTSUPP;
 
-        if (NULL == siocb->scm)
-                siocb->scm = &scm;
-
-        err = scm_send(sock, msg, siocb->scm, true);
+        err = scm_send(sock, msg, &scm, true);
         if (err < 0)
                 return err;
 
@@ -2305,7 +2301,7 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
         if (netlink_tx_is_mmaped(sk) &&
             msg->msg_iter.iov->iov_base == NULL) {
                 err = netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group,
-                                           siocb);
+                                           &scm);
                 goto out;
         }
 
@@ -2319,7 +2315,7 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
 
         NETLINK_CB(skb).portid  = nlk->portid;
         NETLINK_CB(skb).dst_group = dst_group;
-        NETLINK_CB(skb).creds   = siocb->scm->creds;
+        NETLINK_CB(skb).creds   = scm.creds;
         NETLINK_CB(skb).flags   = netlink_skb_flags;
 
         err = -EFAULT;
@@ -2341,7 +2337,7 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
         err = netlink_unicast(sk, skb, dst_portid, msg->msg_flags&MSG_DONTWAIT);
 
 out:
-        scm_destroy(siocb->scm);
+        scm_destroy(&scm);
         return err;
 }
 
@@ -2349,7 +2345,6 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
                            struct msghdr *msg, size_t len,
                            int flags)
 {
-        struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
         struct scm_cookie scm;
         struct sock *sk = sock->sk;
         struct netlink_sock *nlk = nlk_sk(sk);
@@ -2412,11 +2407,8 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
         if (nlk->flags & NETLINK_RECV_PKTINFO)
                 netlink_cmsg_recv_pktinfo(msg, skb);
 
-        if (NULL == siocb->scm) {
-                memset(&scm, 0, sizeof(scm));
-                siocb->scm = &scm;
-        }
-        siocb->scm->creds = *NETLINK_CREDS(skb);
+        memset(&scm, 0, sizeof(scm));
+        scm.creds = *NETLINK_CREDS(skb);
         if (flags & MSG_TRUNC)
                 copied = data_skb->len;
 
@@ -2431,7 +2423,7 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
                 }
         }
 
-        scm_recv(sock, msg, siocb->scm, flags);
+        scm_recv(sock, msg, &scm, flags);
 out:
         netlink_rcv_wake(sk);
         return err ? : copied;
diff --git a/net/socket.c b/net/socket.c
index 3acd35f144d6..3326d67482ac 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -613,13 +613,6 @@ EXPORT_SYMBOL(__sock_tx_timestamp);
 static inline int __sock_sendmsg_nosec(struct kiocb *iocb, struct socket *sock,
                                        struct msghdr *msg, size_t size)
 {
-        struct sock_iocb *si = kiocb_to_siocb(iocb);
-
-        si->sock = sock;
-        si->scm = NULL;
-        si->msg = msg;
-        si->size = size;
-
         return sock->ops->sendmsg(iocb, sock, msg, size);
 }
 
@@ -635,11 +628,9 @@ static int do_sock_sendmsg(struct socket *sock, struct msghdr *msg,
                            size_t size, bool nosec)
 {
         struct kiocb iocb;
-        struct sock_iocb siocb;
         int ret;
 
         init_sync_kiocb(&iocb, NULL);
-        iocb.private = &siocb;
         ret = nosec ? __sock_sendmsg_nosec(&iocb, sock, msg, size) :
                       __sock_sendmsg(&iocb, sock, msg, size);
         if (-EIOCBQUEUED == ret)
@@ -756,14 +747,6 @@ EXPORT_SYMBOL_GPL(__sock_recv_ts_and_drops);
 static inline int __sock_recvmsg_nosec(struct kiocb *iocb, struct socket *sock,
                                        struct msghdr *msg, size_t size, int flags)
 {
-        struct sock_iocb *si = kiocb_to_siocb(iocb);
-
-        si->sock = sock;
-        si->scm = NULL;
-        si->msg = msg;
-        si->size = size;
-        si->flags = flags;
-
         return sock->ops->recvmsg(iocb, sock, msg, size, flags);
 }
 
@@ -779,11 +762,9 @@ int sock_recvmsg(struct socket *sock, struct msghdr *msg,
                  size_t size, int flags)
 {
         struct kiocb iocb;
-        struct sock_iocb siocb;
         int ret;
 
         init_sync_kiocb(&iocb, NULL);
-        iocb.private = &siocb;
         ret = __sock_recvmsg(&iocb, sock, msg, size, flags);
         if (-EIOCBQUEUED == ret)
                 ret = wait_on_sync_kiocb(&iocb);
@@ -795,11 +776,9 @@ static int sock_recvmsg_nosec(struct socket *sock, struct msghdr *msg,
                               size_t size, int flags)
 {
         struct kiocb iocb;
-        struct sock_iocb siocb;
         int ret;
 
         init_sync_kiocb(&iocb, NULL);
-        iocb.private = &siocb;
         ret = __sock_recvmsg_nosec(&iocb, sock, msg, size, flags);
         if (-EIOCBQUEUED == ret)
                 ret = wait_on_sync_kiocb(&iocb);
@@ -866,14 +845,6 @@ static ssize_t sock_splice_read(struct file *file, loff_t *ppos,
         return sock->ops->splice_read(sock, ppos, pipe, len, flags);
 }
 
-static struct sock_iocb *alloc_sock_iocb(struct kiocb *iocb,
-                                         struct sock_iocb *siocb)
-{
-        siocb->kiocb = iocb;
-        iocb->private = siocb;
-        return siocb;
-}
-
 static ssize_t do_sock_read(struct msghdr *msg, struct kiocb *iocb,
                 struct file *file, const struct iovec *iov,
                 unsigned long nr_segs)
@@ -893,7 +864,7 @@ static ssize_t do_sock_read(struct msghdr *msg, struct kiocb *iocb,
 static ssize_t sock_aio_read(struct kiocb *iocb, const struct iovec *iov,
                                 unsigned long nr_segs, loff_t pos)
 {
-        struct sock_iocb siocb, *x;
+        struct msghdr msg;
 
         if (pos != 0)
                 return -ESPIPE;
@@ -901,11 +872,7 @@ static ssize_t sock_aio_read(struct kiocb *iocb, const struct iovec *iov,
         if (iocb->ki_nbytes == 0)       /* Match SYS5 behaviour */
                 return 0;
 
-
-        x = alloc_sock_iocb(iocb, &siocb);
-        if (!x)
-                return -ENOMEM;
-        return do_sock_read(&x->async_msg, iocb, iocb->ki_filp, iov, nr_segs);
+        return do_sock_read(&msg, iocb, iocb->ki_filp, iov, nr_segs);
 }
 
 static ssize_t do_sock_write(struct msghdr *msg, struct kiocb *iocb,
@@ -929,16 +896,12 @@ static ssize_t do_sock_write(struct msghdr *msg, struct kiocb *iocb,
 static ssize_t sock_aio_write(struct kiocb *iocb, const struct iovec *iov,
                           unsigned long nr_segs, loff_t pos)
 {
-        struct sock_iocb siocb, *x;
+        struct msghdr msg;
 
         if (pos != 0)
                 return -ESPIPE;
 
-        x = alloc_sock_iocb(iocb, &siocb);
-        if (!x)
-                return -ENOMEM;
-
-        return do_sock_write(&x->async_msg, iocb, iocb->ki_filp, iov, nr_segs);
+        return do_sock_write(&msg, iocb, iocb->ki_filp, iov, nr_segs);
 }
 
 /*
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 8e1b10274b02..526b6edab018 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1445,7 +1445,6 @@ static void maybe_add_creds(struct sk_buff *skb, const struct socket *sock,
 static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
                               struct msghdr *msg, size_t len)
 {
-        struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
         struct sock *sk = sock->sk;
         struct net *net = sock_net(sk);
         struct unix_sock *u = unix_sk(sk);
@@ -1456,14 +1455,12 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
         unsigned int hash;
         struct sk_buff *skb;
         long timeo;
-        struct scm_cookie tmp_scm;
+        struct scm_cookie scm;
         int max_level;
         int data_len = 0;
 
-        if (NULL == siocb->scm)
-                siocb->scm = &tmp_scm;
         wait_for_unix_gc();
-        err = scm_send(sock, msg, siocb->scm, false);
+        err = scm_send(sock, msg, &scm, false);
         if (err < 0)
                 return err;
 
@@ -1507,11 +1504,11 @@ 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);
+        err = unix_scm_to_skb(&scm, skb, true);
         if (err < 0)
                 goto out_free;
         max_level = err + 1;
-        unix_get_secdata(siocb->scm, skb);
+        unix_get_secdata(&scm, skb);
 
         skb_put(skb, len - data_len);
         skb->data_len = data_len;
@@ -1606,7 +1603,7 @@ restart:
         unix_state_unlock(other);
         other->sk_data_ready(other);
         sock_put(other);
-        scm_destroy(siocb->scm);
+        scm_destroy(&scm);
         return len;
 
 out_unlock:
@@ -1616,7 +1613,7 @@ out_free:
 out:
         if (other)
                 sock_put(other);
-        scm_destroy(siocb->scm);
+        scm_destroy(&scm);
         return err;
 }
 
@@ -1628,21 +1625,18 @@ out:
 static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
                                struct msghdr *msg, size_t len)
 {
-        struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
         struct sock *sk = sock->sk;
         struct sock *other = NULL;
         int err, size;
         struct sk_buff *skb;
         int sent = 0;
-        struct scm_cookie tmp_scm;
+        struct scm_cookie scm;
         bool fds_sent = false;
         int max_level;
         int data_len;
 
-        if (NULL == siocb->scm)
-                siocb->scm = &tmp_scm;
         wait_for_unix_gc();
-        err = scm_send(sock, msg, siocb->scm, false);
+        err = scm_send(sock, msg, &scm, false);
         if (err < 0)
                 return err;
 
@@ -1683,7 +1677,7 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
                         goto out_err;
 
                 /* Only send the fds in the first buffer */
-                err = unix_scm_to_skb(siocb->scm, skb, !fds_sent);
+                err = unix_scm_to_skb(&scm, skb, !fds_sent);
                 if (err < 0) {
                         kfree_skb(skb);
                         goto out_err;
@@ -1715,8 +1709,7 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
                 sent += size;
         }
 
-        scm_destroy(siocb->scm);
-        siocb->scm = NULL;
+        scm_destroy(&scm);
 
         return sent;
 
@@ -1728,8 +1721,7 @@ pipe_err:
                 send_sig(SIGPIPE, current, 0);
         err = -EPIPE;
 out_err:
-        scm_destroy(siocb->scm);
-        siocb->scm = NULL;
+        scm_destroy(&scm);
         return sent ? : err;
 }
 
@@ -1778,8 +1770,7 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
                               struct msghdr *msg, size_t size,
                               int flags)
 {
-        struct sock_iocb *siocb = kiocb_to_siocb(iocb);
-        struct scm_cookie tmp_scm;
+        struct scm_cookie scm;
         struct sock *sk = sock->sk;
         struct unix_sock *u = unix_sk(sk);
         int noblock = flags & MSG_DONTWAIT;
@@ -1831,16 +1822,14 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
         if (sock_flag(sk, SOCK_RCVTSTAMP))
                 __sock_recv_timestamp(msg, sk, skb);
 
-        if (!siocb->scm) {
-                siocb->scm = &tmp_scm;
-                memset(&tmp_scm, 0, sizeof(tmp_scm));
-        }
-        scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
-        unix_set_secdata(siocb->scm, skb);
+        memset(&scm, 0, sizeof(scm));
+
+        scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
+        unix_set_secdata(&scm, skb);
 
         if (!(flags & MSG_PEEK)) {
                 if (UNIXCB(skb).fp)
-                        unix_detach_fds(siocb->scm, skb);
+                        unix_detach_fds(&scm, skb);
 
                 sk_peek_offset_bwd(sk, skb->len);
         } else {
@@ -1860,11 +1849,11 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
                 sk_peek_offset_fwd(sk, size);
 
                 if (UNIXCB(skb).fp)
-                        siocb->scm->fp = scm_fp_dup(UNIXCB(skb).fp);
+                        scm.fp = scm_fp_dup(UNIXCB(skb).fp);
         }
         err = (flags & MSG_TRUNC) ? skb->len - skip : size;
 
-        scm_recv(sock, msg, siocb->scm, flags);
+        scm_recv(sock, msg, &scm, flags);
 
 out_free:
         skb_free_datagram(sk, skb);
@@ -1915,8 +1904,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
                                struct msghdr *msg, size_t size,
                                int flags)
 {
-        struct sock_iocb *siocb = kiocb_to_siocb(iocb);
-        struct scm_cookie tmp_scm;
+        struct scm_cookie scm;
         struct sock *sk = sock->sk;
         struct unix_sock *u = unix_sk(sk);
         DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, msg->msg_name);
@@ -1943,10 +1931,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
          * while sleeps in memcpy_tomsg
          */
 
-        if (!siocb->scm) {
-                siocb->scm = &tmp_scm;
-                memset(&tmp_scm, 0, sizeof(tmp_scm));
-        }
+        memset(&scm, 0, sizeof(scm));
 
         err = mutex_lock_interruptible(&u->readlock);
         if (unlikely(err)) {
@@ -2012,13 +1997,13 @@ again:
 
                 if (check_creds) {
                         /* Never glue messages from different writers */
-                        if ((UNIXCB(skb).pid  != siocb->scm->pid) ||
-                            !uid_eq(UNIXCB(skb).uid, siocb->scm->creds.uid) ||
-                            !gid_eq(UNIXCB(skb).gid, siocb->scm->creds.gid))
+                        if ((UNIXCB(skb).pid  != scm.pid) ||
+                            !uid_eq(UNIXCB(skb).uid, scm.creds.uid) ||
+                            !gid_eq(UNIXCB(skb).gid, scm.creds.gid))
                                 break;
                 } else if (test_bit(SOCK_PASSCRED, &sock->flags)) {
                         /* Copy credentials */
-                        scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
+                        scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
                         check_creds = 1;
                 }
 
@@ -2045,7 +2030,7 @@ again:
                         sk_peek_offset_bwd(sk, chunk);
 
                         if (UNIXCB(skb).fp)
-                                unix_detach_fds(siocb->scm, skb);
+                                unix_detach_fds(&scm, skb);
 
                         if (unix_skb_len(skb))
                                 break;
@@ -2053,13 +2038,13 @@ again:
                         skb_unlink(skb, &sk->sk_receive_queue);
                         consume_skb(skb);
 
-                        if (siocb->scm->fp)
+                        if (scm.fp)
                                 break;
                 } else {
                         /* It is questionable, see note in unix_dgram_recvmsg.
                          */
                         if (UNIXCB(skb).fp)
-                                siocb->scm->fp = scm_fp_dup(UNIXCB(skb).fp);
+                                scm.fp = scm_fp_dup(UNIXCB(skb).fp);
 
                         sk_peek_offset_fwd(sk, chunk);
 
@@ -2068,7 +2053,7 @@ again:
         } while (size);
 
         mutex_unlock(&u->readlock);
-        scm_recv(sock, msg, siocb->scm, flags);
+        scm_recv(sock, msg, &scm, flags);
 out:
         return copied ? : err;
 }