net: change big iov allocations

iov of more than 8 entries are allocated in sendmsg()/recvmsg() through
sock_kmalloc()

As these allocations are temporary only and small enough, it makes sense
to use plain kmalloc() and avoid sk_omem_alloc atomic overhead.

Slightly changed fast path to be even faster.

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

1 files changed, 16 insertions, 21 deletions

diff --git a/net/socket.c b/net/socket.c
index e34510928dcc..d3aaa4f67a3b 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1908,7 +1908,7 @@ static int __sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
             __attribute__ ((aligned(sizeof(__kernel_size_t))));
         /* 20 is size of ipv6_pktinfo */
         unsigned char *ctl_buf = ctl;
-        int err, ctl_len, iov_size, total_len;
+        int err, ctl_len, total_len;
 
         err = -EFAULT;
         if (MSG_CMSG_COMPAT & flags) {
@@ -1917,16 +1917,13 @@ static int __sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
         } else if (copy_from_user(msg_sys, msg, sizeof(struct msghdr)))
                 return -EFAULT;
 
-        /* do not move before msg_sys is valid */
-        err = -EMSGSIZE;
-        if (msg_sys->msg_iovlen > UIO_MAXIOV)
-                goto out;
-
-        /* Check whether to allocate the iovec area */
-        err = -ENOMEM;
-        iov_size = msg_sys->msg_iovlen * sizeof(struct iovec);
         if (msg_sys->msg_iovlen > UIO_FASTIOV) {
-                iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL);
+                err = -EMSGSIZE;
+                if (msg_sys->msg_iovlen > UIO_MAXIOV)
+                        goto out;
+                err = -ENOMEM;
+                iov = kmalloc(msg_sys->msg_iovlen * sizeof(struct iovec),
+                              GFP_KERNEL);
                 if (!iov)
                         goto out;
         }
@@ -2005,7 +2002,7 @@ out_freectl:
                 sock_kfree_s(sock->sk, ctl_buf, ctl_len);
 out_freeiov:
         if (iov != iovstack)
-                sock_kfree_s(sock->sk, iov, iov_size);
+                kfree(iov);
 out:
         return err;
 }
@@ -2103,7 +2100,7 @@ static int __sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
         struct iovec iovstack[UIO_FASTIOV];
         struct iovec *iov = iovstack;
         unsigned long cmsg_ptr;
-        int err, iov_size, total_len, len;
+        int err, total_len, len;
 
         /* kernel mode address */
         struct sockaddr_storage addr;
@@ -2118,15 +2115,13 @@ static int __sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
         } else if (copy_from_user(msg_sys, msg, sizeof(struct msghdr)))
                 return -EFAULT;
 
-        err = -EMSGSIZE;
-        if (msg_sys->msg_iovlen > UIO_MAXIOV)
-                goto out;
-
-        /* Check whether to allocate the iovec area */
-        err = -ENOMEM;
-        iov_size = msg_sys->msg_iovlen * sizeof(struct iovec);
         if (msg_sys->msg_iovlen > UIO_FASTIOV) {
-                iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL);
+                err = -EMSGSIZE;
+                if (msg_sys->msg_iovlen > UIO_MAXIOV)
+                        goto out;
+                err = -ENOMEM;
+                iov = kmalloc(msg_sys->msg_iovlen * sizeof(struct iovec),
+                              GFP_KERNEL);
                 if (!iov)
                         goto out;
         }
@@ -2180,7 +2175,7 @@ static int __sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
 
 out_freeiov:
         if (iov != iovstack)
-                sock_kfree_s(sock->sk, iov, iov_size);
+                kfree(iov);
 out:
         return err;
 }