From: Neil Horman <nhorman@redhat.com> Date: Tue, 15 Sep 2009 16:11:22 -0400 Subject: [net] fix drop monitor to not panic on null dev Message-id: 20090915201122.GI1366@hmsreliant.think-freely.org O-Subject: [RHEL 5.5 PATCH]: fix drop monitor to not panic on null dev (bz 523279) Bugzilla: 523279 RH-Acked-by: David Miller <davem@redhat.com> RH-Acked-by: Dean Nelson <dnelson@redhat.com> RH-Acked-by: Rik van Riel <riel@redhat.com> RH-Acked-by: Prarit Bhargava <prarit@redhat.com> Hey all- A customer has been messing with dropwatch, and they noticed a panic that has since been fixed upstream. This patch is a massage of upstream commit f2798eb4e01b095f273f4bf40f511c9d69c0e1da which fixes it. Satisfies bz 523279 diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c index 8016ac4..bc86ca9 100644 --- a/net/core/drop_monitor.c +++ b/net/core/drop_monitor.c @@ -173,13 +173,23 @@ static void trace_napi_poll_hit(struct net_device *napi) { struct dm_hw_stat_delta *new_stat; struct net_device_stats *stats; + + if (!napi) + return; /* * Ratelimit our check time to dm_hw_check_delta jiffies */ if (!time_after(jiffies, napi->last_rx + dm_hw_check_delta)) return; - + + if (!napi->get_stats) + return; + + stats = napi->get_stats(napi); + if (!stats) + return; + rcu_read_lock(); list_for_each_entry_rcu(new_stat, &hw_stats_list, list) { stats = napi->get_stats(napi);