net/mlx5e: Disable preemption when doing TC statistics upcall

ogerlitz · davem330 · commit fed06ee89b78 · 2017-02-14T11:56:01.000-05:00
When called by HW offloading drivers, the TC action (e.g net/sched/act_mirred.c) code uses this_cpu logic, e.g _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets) per the kernel documention, preemption should be disabled, add that. Before the fix, when running with CONFIG_PREEMPT set, we get a BUG: using smp_processor_id() in preemptible [00000000] code: tc/3793 asserion from the TC action (mirred) stats_update callback. Fixes: aad7e08 ('net/mlx5e: Hardware offloaded flower filter statistics support') Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -1087,10 +1087,14 @@ int mlx5e_stats_flower(struct mlx5e_priv *priv,
 
 	mlx5_fc_query_cached(counter, &bytes, &packets, &lastuse);
 
+	preempt_disable();
+
 	tcf_exts_to_list(f->exts, &actions);
 	list_for_each_entry(a, &actions, list)
 		tcf_action_stats_update(a, bytes, packets, lastuse);
 
+	preempt_enable();
+
 	return 0;
 }
 
