From: Eric Dumazet <eric.dumazet@gmail.com>
To: Manish Kurup <kurup.manish@gmail.com>
Cc: jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us,
davem@davemloft.net, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, aring@mojatatu.com,
mrv@mojatatu.com, manish.kurup@verizon.com
Subject: Re: [PATCH net-next 2/2] net sched act_vlan: VLAN action rewrite to use RCU lock/unlock and update
Date: Wed, 11 Oct 2017 06:10:29 -0700 [thread overview]
Message-ID: <1507727429.31614.22.camel@edumazet-glaptop3.roam.corp.google.com> (raw)
In-Reply-To: <1507689219-22993-1-git-send-email-manish.kurup@verizon.com>
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.kurup@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.
next prev parent reply other threads:[~2017-10-11 13:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-11 2:33 [PATCH net-next 2/2] net sched act_vlan: VLAN action rewrite to use RCU lock/unlock and update Manish Kurup
2017-10-11 12:28 ` Jamal Hadi Salim
2017-10-11 13:10 ` Eric Dumazet [this message]
2017-10-11 13:30 ` Eric Dumazet
2017-10-11 13:13 ` Jiri Pirko
2017-10-11 16:27 ` Cong Wang
2017-10-11 20:41 ` Jiri Pirko
-- strict thread matches above, loose matches on Subject: below --
2017-10-11 1:52 Manish Kurup
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