Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[karo-tx-linux.git] / net / netlink / af_netlink.c

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 8f060d7f9a0e107a410d3ffe71722f49059f7bc8..fafe33bdb61989e680dc4b26dbe99dcc1d4064b5 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2371,7 +2371,7 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
                int pos, idx, shift;
 
                err = 0;
-               netlink_table_grab();
+               netlink_lock_table();
                for (pos = 0; pos * 8 < nlk->ngroups; pos += sizeof(u32)) {
                        if (len - pos < sizeof(u32))
                                break;
@@ -2386,7 +2386,7 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
                }
                if (put_user(ALIGN(nlk->ngroups / 8, sizeof(u32)), optlen))
                        err = -EFAULT;
-               netlink_table_ungrab();
+               netlink_unlock_table();
                break;
        }
        case NETLINK_CAP_ACK:
@@ -2785,6 +2785,7 @@ static int netlink_dump(struct sock *sk)
        struct sk_buff *skb = NULL;
        struct nlmsghdr *nlh;
        int len, err = -ENOBUFS;
+       int alloc_min_size;
        int alloc_size;
 
        mutex_lock(nlk->cb_mutex);
@@ -2793,9 +2794,6 @@ static int netlink_dump(struct sock *sk)
                goto errout_skb;
        }
 
-       cb = &nlk->cb;
-       alloc_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
-
        if (!netlink_rx_is_mmaped(sk) &&
            atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
                goto errout_skb;
@@ -2805,23 +2803,35 @@ static int netlink_dump(struct sock *sk)
         * to reduce number of system calls on dump operations, if user
         * ever provided a big enough buffer.
         */
-       if (alloc_size < nlk->max_recvmsg_len) {
-               skb = netlink_alloc_skb(sk,
-                                       nlk->max_recvmsg_len,
-                                       nlk->portid,
+       cb = &nlk->cb;
+       alloc_min_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
+
+       if (alloc_min_size < nlk->max_recvmsg_len) {
+               alloc_size = nlk->max_recvmsg_len;
+               skb = netlink_alloc_skb(sk, alloc_size, nlk->portid,
                                        GFP_KERNEL |
                                        __GFP_NOWARN |
                                        __GFP_NORETRY);
-               /* available room should be exact amount to avoid MSG_TRUNC */
-               if (skb)
-                       skb_reserve(skb, skb_tailroom(skb) -
-                                        nlk->max_recvmsg_len);
        }
-       if (!skb)
+       if (!skb) {
+               alloc_size = alloc_min_size;
                skb = netlink_alloc_skb(sk, alloc_size, nlk->portid,
                                        GFP_KERNEL);
+       }
        if (!skb)
                goto errout_skb;
+
+       /* Trim skb to allocated size. User is expected to provide buffer as
+        * large as max(min_dump_alloc, 16KiB (mac_recvmsg_len capped at
+        * netlink_recvmsg())). dump will pack as many smaller messages as
+        * could fit within the allocated skb. skb is typically allocated
+        * with larger space than required (could be as much as near 2x the
+        * requested size with align to next power of 2 approach). Allowing
+        * dump to use the excess space makes it difficult for a user to have a
+        * reasonable static buffer based on the expected largest dump of a
+        * single netdev. The outcome is MSG_TRUNC error.
+        */
+       skb_reserve(skb, skb_tailroom(skb) - alloc_size);
        netlink_skb_set_owner_r(skb, sk);
 
        len = cb->dump(skb, cb);