ipv4: Restore fib_trie_flush_external function and fix call ordering

[ Upstream commit 3b7093346b326e5d3590c7d49f6aefe6fa5b2c9a, the FIB offload
  removal didn't occur in 4.8 so that part of this patch isn't here.  However
  we still need to fib_unmerge() bits. ]

The patch that removed the FIB offload infrastructure was a bit too
aggressive and also removed code needed to clean up us splitting the table
if additional rules were added.  Specifically the function
fib_trie_flush_external was called at the end of a new rule being added to
flush the foreign trie entries from the main trie.

I updated the code so that we only call fib_trie_flush_external on the main
table so that we flush the entries for local from main.  This way we don't
call it for every rule change which is what was happening previously.

Fixes: 347e3b28c1ba2 ("switchdev: remove FIB offload infrastructure")
Reported-by: Eric Dumazet <edumazet@google.com>
Cc: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 1b25daf8c7f12ada5a6ea7178d95c6c086f9098d..9301308528f83eb819fb03c0930e72eaf6e7e52a 100644 (file)
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -157,7 +157,7 @@ static void fib_replace_table(struct net *net, struct fib_table *old,
 
 int fib_unmerge(struct net *net)
 {
-       struct fib_table *old, *new;
+       struct fib_table *old, *new, *main_table;
 
        /* attempt to fetch local table if it has been allocated */
        old = fib_get_table(net, RT_TABLE_LOCAL);
@@ -168,11 +168,21 @@ int fib_unmerge(struct net *net)
        if (!new)
                return -ENOMEM;
 
+       /* table is already unmerged */
+       if (new == old)
+               return 0;
+
        /* replace merged table with clean table */
-       if (new != old) {
-               fib_replace_table(net, old, new);
-               fib_free_table(old);
-       }
+       fib_replace_table(net, old, new);
+       fib_free_table(old);
+
+       /* attempt to fetch main table if it has been allocated */
+       main_table = fib_get_table(net, RT_TABLE_MAIN);
+       if (!main_table)
+               return 0;
+
+       /* flush local entries from main table */
+       fib_table_flush_external(main_table);
 
        return 0;
 }