From a664a4f7aa4f01ca8728e3ec43618327416fc8ff Mon Sep 17 00:00:00 2001 From: Shlomo Pongratz Date: Sun, 2 Feb 2014 15:42:10 +0200 Subject: [PATCH] net/ipv4: Use proper RCU APIs for writer-side in udp_offload.c RCU writer side should use rcu_dereference_protected() and not rcu_dereference(), fix that. This also removes the "suspicious RCU usage" warning seen when running with CONFIG_PROVE_RCU. Also, don't use rcu_assign_pointer/rcu_dereference for pointers which are invisible beyond the udp offload code. Fixes: b582ef0 ('net: Add GRO support for UDP encapsulating protocols') Reported-by: Eric Dumazet Cc: Eric Dumazet Signed-off-by: Or Gerlitz Signed-off-by: Shlomo Pongratz Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/udp_offload.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index 2ffea6f31efc..88b4023ecfcf 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -17,6 +17,8 @@ static DEFINE_SPINLOCK(udp_offload_lock); static struct udp_offload_priv __rcu *udp_offload_base __read_mostly; +#define udp_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&udp_offload_lock)) + struct udp_offload_priv { struct udp_offload *offload; struct rcu_head rcu; @@ -100,7 +102,6 @@ out: int udp_add_offload(struct udp_offload *uo) { - struct udp_offload_priv __rcu **head = &udp_offload_base; struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_ATOMIC); if (!new_offload) @@ -109,8 +110,8 @@ int udp_add_offload(struct udp_offload *uo) new_offload->offload = uo; spin_lock(&udp_offload_lock); - rcu_assign_pointer(new_offload->next, rcu_dereference(*head)); - rcu_assign_pointer(*head, new_offload); + new_offload->next = udp_offload_base; + rcu_assign_pointer(udp_offload_base, new_offload); spin_unlock(&udp_offload_lock); return 0; @@ -130,12 +131,12 @@ void udp_del_offload(struct udp_offload *uo) spin_lock(&udp_offload_lock); - uo_priv = rcu_dereference(*head); + uo_priv = udp_deref_protected(*head); for (; uo_priv != NULL; - uo_priv = rcu_dereference(*head)) { - + uo_priv = udp_deref_protected(*head)) { if (uo_priv->offload == uo) { - rcu_assign_pointer(*head, rcu_dereference(uo_priv->next)); + rcu_assign_pointer(*head, + udp_deref_protected(uo_priv->next)); goto unlock; } head = &uo_priv->next; -- 2.30.2