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Commit a35165ca authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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ipv4: do not use this_cpu_ptr() in preemptible context 

this_cpu_ptr() in preemptible context is generally bad

Sep 22 05:05:55 br kernel: [   94.608310] BUG: using smp_processor_id()
in
preemptible [00000000] code: ip/2261
Sep 22 05:05:55 br kernel: [   94.608316] caller is
tunnel_dst_set.isra.28+0x20/0x60 [ip_tunnel]
Sep 22 05:05:55 br kernel: [   94.608319] CPU: 3 PID: 2261 Comm: ip Not
tainted
3.17.0-rc5 #82

We can simply use raw_cpu_ptr(), as preemption is safe in these
contexts.

Should fix https://bugzilla.kernel.org/show_bug.cgi?id=84991



Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarJoe <joe9mail@gmail.com>
Fixes: 9a4aa9af ("ipv4: Use percpu Cache route in IP tunnels")
Acked-by: default avatarTom Herbert <therbert@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 84de67b2

net/ipv4/ip_tunnel.c

+3 −3
Original line number Diff line number Diff line
@@ -79,10 +79,10 @@ static void __tunnel_dst_set(struct ip_tunnel_dst *idst, 
	idst->saddr = saddr;

}



static void tunnel_dst_set(struct ip_tunnel *t,

static noinline void tunnel_dst_set(struct ip_tunnel *t,

			   struct dst_entry *dst, __be32 saddr)

{

	__tunnel_dst_set(this_cpu_ptr(t->dst_cache), dst, saddr);

	__tunnel_dst_set(raw_cpu_ptr(t->dst_cache), dst, saddr);

}



static void tunnel_dst_reset(struct ip_tunnel *t)
@@ -106,7 +106,7 @@ static struct rtable *tunnel_rtable_get(struct ip_tunnel *t, 
	struct dst_entry *dst;



	rcu_read_lock();

	idst = this_cpu_ptr(t->dst_cache);

	idst = raw_cpu_ptr(t->dst_cache);

	dst = rcu_dereference(idst->dst);

	if (dst && !atomic_inc_not_zero(&dst->__refcnt))

		dst = NULL;