On Tue, 2017-10-10 at 22:33 -0400, Manish Kurup wrote:
> Using a spinlock in the VLAN action causes performance issues when the VLAN
> action is used on multiple cores. Rewrote the VLAN action to use RCU read
> locking for reads and updates instead.
>
> Signed-off-by: Manish Kurup <manish.ku...@verizon.com>
> ---
> include/net/tc_act/tc_vlan.h | 21 ++++++++-----
> net/sched/act_vlan.c | 73
> ++++++++++++++++++++++++++++++--------------
> 2 files changed, 63 insertions(+), 31 deletions(-)
>
> diff --git a/include/net/tc_act/tc_vlan.h b/include/net/tc_act/tc_vlan.h
> index c2090df..67fd355 100644
> --- a/include/net/tc_act/tc_vlan.h
> +++ b/include/net/tc_act/tc_vlan.h
> @@ -13,12 +13,17 @@
> #include <net/act_api.h>
> #include <linux/tc_act/tc_vlan.h>
>
> +struct tcf_vlan_params {
> + struct rcu_head rcu;
> + int tcfv_action;
> + u16 tcfv_push_vid;
> + __be16 tcfv_push_proto;
> + u8 tcfv_push_prio;
> +};
> +
> struct tcf_vlan {
> struct tc_action common;
> - int tcfv_action;
> - u16 tcfv_push_vid;
> - __be16 tcfv_push_proto;
> - u8 tcfv_push_prio;
> + struct tcf_vlan_params __rcu *vlan_p;
> };
> #define to_vlan(a) ((struct tcf_vlan *)a)
>
> @@ -33,22 +38,22 @@ static inline bool is_tcf_vlan(const struct tc_action *a)
>
> static inline u32 tcf_vlan_action(const struct tc_action *a)
> {
> - return to_vlan(a)->tcfv_action;
> + return to_vlan(a)->vlan_p->tcfv_action;
This is not proper RCU : ->vlan_p should be read once, and using
rcu_dereference()
So the caller should provide to this helper the 'p' pointer instead of
'a'
CONFIG_SPARSE_RCU_POINTER=y
and make C=2 would probably give you warnings about that.
