[PATCH 3.12 107/127] neigh: check error pointer instead of NULL for ipv4_neigh_lookup()

From: WANG Cong 3.12-stable review patch. If anyone has any objections, please let me know. === commit 2c1a4311b61072afe2309d4152a7993e92caa41c upstream. Fixes: commit f187bc6efb7250afee0e2009b6106 ("ipv4: No need to set generic neighbour pointer") Cc:

[PATCH 3.12 107/127] neigh: check error pointer instead of NULL for ipv4_neigh_lookup()

From: WANG Cong 3.12-stable review patch. If anyone has any objections, please let me know. === commit 2c1a4311b61072afe2309d4152a7993e92caa41c upstream. Fixes: commit f187bc6efb7250afee0e2009b6106 ("ipv4: No need to set generic neighbour pointer") Cc: David S. Miller