rtnetlink: Compute and store minimum ifinfo dump size

The message size allocated for rtnl ifinfo dumps was limited to
a single page.  This is not enough for additional interface info
available with devices that support SR-IOV and caused a bug in
which VF info would not be displayed if more than approximately
40 VFs were created per interface.

Implement a new function pointer for the rtnl_register service that will
calculate the amount of data required for the ifinfo dump and allocate
enough data to satisfy the request.

Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 11 insertions, 6 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 6ef64adf7362..0b92f75491b1 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1659,13 +1659,10 @@ static int netlink_dump(struct sock *sk)
 {
         struct netlink_sock *nlk = nlk_sk(sk);
         struct netlink_callback *cb;
-        struct sk_buff *skb;
+        struct sk_buff *skb = NULL;
         struct nlmsghdr *nlh;
         int len, err = -ENOBUFS;
-
-        skb = sock_rmalloc(sk, NLMSG_GOODSIZE, 0, GFP_KERNEL);
-        if (!skb)
-                goto errout;
+        int alloc_size;
 
         mutex_lock(nlk->cb_mutex);
 
@@ -1675,6 +1672,12 @@ static int netlink_dump(struct sock *sk)
                 goto errout_skb;
         }
 
+        alloc_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
+
+        skb = sock_rmalloc(sk, alloc_size, 0, GFP_KERNEL);
+        if (!skb)
+                goto errout;
+
         len = cb->dump(skb, cb);
 
         if (len > 0) {
@@ -1721,7 +1724,8 @@ int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
                        const struct nlmsghdr *nlh,
                        int (*dump)(struct sk_buff *skb,
                                    struct netlink_callback *),
-                       int (*done)(struct netlink_callback *))
+                       int (*done)(struct netlink_callback *),
+                       u16 min_dump_alloc)
 {
         struct netlink_callback *cb;
         struct sock *sk;
@@ -1735,6 +1739,7 @@ int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
         cb->dump = dump;
         cb->done = done;
         cb->nlh = nlh;
+        cb->min_dump_alloc = min_dump_alloc;
         atomic_inc(&skb->users);
         cb->skb = skb;