ipv4: do not use this_cpu_ptr() in preemptible context

edumazet · davem330 · commit a35165ca1016 · 2014-09-22T18:31:18.000-04:00
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 torvalds#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: Eric Dumazet <edumazet@google.com> Reported-by: Joe <joe9mail@gmail.com> Fixes: 9a4aa9a ("ipv4: Use percpu Cache route in IP tunnels") Acked-by: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
@@ -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;

Original file line number	Diff line number	Diff line change
`@@ -79,10 +79,10 @@ static void __tunnel_dst_set(struct ip_tunnel_dst *idst,`
`79`	`79`	`idst->saddr = saddr;`
`80`	`80`	`}`
`81`	`81`
`82`		`-static void tunnel_dst_set(struct ip_tunnel *t,`
	`82`	`+static noinline void tunnel_dst_set(struct ip_tunnel *t,`
`83`	`83`	`struct dst_entry *dst, __be32 saddr)`
`84`	`84`	`{`
`85`		`- __tunnel_dst_set(this_cpu_ptr(t->dst_cache), dst, saddr);`
	`85`	`+ __tunnel_dst_set(raw_cpu_ptr(t->dst_cache), dst, saddr);`
`86`	`86`	`}`
`87`	`87`
`88`	`88`	`static void tunnel_dst_reset(struct ip_tunnel *t)`
`@@ -106,7 +106,7 @@ static struct rtable tunnel_rtable_get(struct ip_tunnel t,`
`106`	`106`	`struct dst_entry *dst;`
`107`	`107`
`108`	`108`	`rcu_read_lock();`
`109`		`- idst = this_cpu_ptr(t->dst_cache);`
	`109`	`+ idst = raw_cpu_ptr(t->dst_cache);`
`110`	`110`	`dst = rcu_dereference(idst->dst);`
`111`	`111`	`if (dst && !atomic_inc_not_zero(&dst->__refcnt))`
`112`	`112`	`dst = NULL;`