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Message-ID: <54130DA8.8030906@gmail.com>
Date: Fri, 12 Sep 2014 08:13:44 -0700
From: John Fastabend <john.fastabend@...il.com>
To: Eric Dumazet <eric.dumazet@...il.com>
CC: xiyou.wangcong@...il.com, davem@...emloft.net, jhs@...atatu.com,
netdev@...r.kernel.org, paulmck@...ux.vnet.ibm.com,
brouer@...hat.com
Subject: Re: [net-next PATCH v4 11/16] net: sched: rcu'ify cls_rsvp
On 09/10/2014 06:30 PM, Eric Dumazet wrote:
> On Wed, 2014-09-10 at 08:51 -0700, John Fastabend wrote:
>> Signed-off-by: John Fastabend <john.r.fastabend@...el.com>
>> ---
>> net/sched/cls_rsvp.h | 157 ++++++++++++++++++++++++++++----------------------
>> 1 file changed, 89 insertions(+), 68 deletions(-)
>>
>> diff --git a/net/sched/cls_rsvp.h b/net/sched/cls_rsvp.h
>> index 1020e23..afa508b 100644
>> --- a/net/sched/cls_rsvp.h
>> +++ b/net/sched/cls_rsvp.h
>> @@ -70,31 +70,34 @@ struct rsvp_head {
>> u32 tmap[256/32];
>> u32 hgenerator;
>> u8 tgenerator;
>> - struct rsvp_session *ht[256];
>> + struct rsvp_session __rcu *ht[256];
>> + struct rcu_head rcu;
>> };
>>
>> struct rsvp_session {
>> - struct rsvp_session *next;
>> - __be32 dst[RSVP_DST_LEN];
>> - struct tc_rsvp_gpi dpi;
>> - u8 protocol;
>> - u8 tunnelid;
>> + struct rsvp_session __rcu *next;
>> + __be32 dst[RSVP_DST_LEN];
>> + struct tc_rsvp_gpi dpi;
>> + u8 protocol;
>> + u8 tunnelid;
>> /* 16 (src,sport) hash slots, and one wildcard source slot */
>> - struct rsvp_filter *ht[16 + 1];
>> + struct rsvp_filter __rcu *ht[16 + 1];
>> + struct rcu_head rcu;
>> };
>>
>>
>> struct rsvp_filter {
>> - struct rsvp_filter *next;
>> - __be32 src[RSVP_DST_LEN];
>> - struct tc_rsvp_gpi spi;
>> - u8 tunnelhdr;
>> + struct rsvp_filter __rcu *next;
>> + __be32 src[RSVP_DST_LEN];
>> + struct tc_rsvp_gpi spi;
>> + u8 tunnelhdr;
>>
>> - struct tcf_result res;
>> - struct tcf_exts exts;
>> + struct tcf_result res;
>> + struct tcf_exts exts;
>>
>> - u32 handle;
>> - struct rsvp_session *sess;
>> + u32 handle;
>> + struct rsvp_session *sess;
>> + struct rcu_head rcu;
>> };
>>
>> static inline unsigned int hash_dst(__be32 *dst, u8 protocol, u8 tunnelid)
>> @@ -128,7 +131,7 @@ static inline unsigned int hash_src(__be32 *src)
>> static int rsvp_classify(struct sk_buff *skb, const struct tcf_proto *tp,
>> struct tcf_result *res)
>> {
>> - struct rsvp_session **sht = ((struct rsvp_head *)tp->root)->ht;
>> + struct rsvp_head *head = rcu_dereference_bh(tp->root);
>> struct rsvp_session *s;
>> struct rsvp_filter *f;
>> unsigned int h1, h2;
>> @@ -169,7 +172,8 @@ restart:
>> h1 = hash_dst(dst, protocol, tunnelid);
>> h2 = hash_src(src);
>>
>> - for (s = sht[h1]; s; s = s->next) {
>> + for (s = rcu_dereference_bh(head->ht[h1]); s;
>> + s = rcu_dereference_bh(s->next)) {
>> if (dst[RSVP_DST_LEN-1] == s->dst[RSVP_DST_LEN - 1] &&
>> protocol == s->protocol &&
>> !(s->dpi.mask &
>> @@ -181,7 +185,8 @@ restart:
>> #endif
>> tunnelid == s->tunnelid) {
>>
>> - for (f = s->ht[h2]; f; f = f->next) {
>> + for (f = rcu_dereference_bh(s->ht[h2]); f;
>> + f = rcu_dereference_bh(f->next)) {
>> if (src[RSVP_DST_LEN-1] == f->src[RSVP_DST_LEN - 1] &&
>> !(f->spi.mask & (*(u32 *)(xprt + f->spi.offset) ^ f->spi.key))
>> #if RSVP_DST_LEN == 4
>> @@ -205,7 +210,8 @@ matched:
>> }
>>
>> /* And wildcard bucket... */
>> - for (f = s->ht[16]; f; f = f->next) {
>> + for (f = rcu_dereference_bh(s->ht[16]); f;
>> + f = rcu_dereference_bh(f->next)) {
>> *res = f->res;
>> RSVP_APPLY_RESULT();
>> goto matched;
>> @@ -218,7 +224,7 @@ matched:
>>
>> static unsigned long rsvp_get(struct tcf_proto *tp, u32 handle)
>> {
>> - struct rsvp_session **sht = ((struct rsvp_head *)tp->root)->ht;
>> + struct rsvp_head *head = rtnl_dereference(tp->root);
>> struct rsvp_session *s;
>> struct rsvp_filter *f;
>> unsigned int h1 = handle & 0xFF;
>> @@ -227,8 +233,10 @@ static unsigned long rsvp_get(struct tcf_proto *tp, u32 handle)
>> if (h2 > 16)
>> return 0;
>>
>> - for (s = sht[h1]; s; s = s->next) {
>> - for (f = s->ht[h2]; f; f = f->next) {
>> + for (s = rtnl_dereference(head->ht[h1]); s;
>> + s = rtnl_dereference(s->next)) {
>> + for (f = rtnl_dereference(s->ht[h2]); f;
>> + f = rtnl_dereference(f->next)) {
>> if (f->handle == handle)
>> return (unsigned long)f;
>> }
>> @@ -246,7 +254,7 @@ static int rsvp_init(struct tcf_proto *tp)
>>
>> data = kzalloc(sizeof(struct rsvp_head), GFP_KERNEL);
>> if (data) {
>> - tp->root = data;
>> + rcu_assign_pointer(tp->root, data);
>> return 0;
>> }
>> return -ENOBUFS;
>> @@ -257,53 +265,55 @@ rsvp_delete_filter(struct tcf_proto *tp, struct rsvp_filter *f)
>> {
>> tcf_unbind_filter(tp, &f->res);
>> tcf_exts_destroy(tp, &f->exts);
>> - kfree(f);
>> + kfree_rcu(f, rcu);
>> }
>>
>> static void rsvp_destroy(struct tcf_proto *tp)
>> {
>> - struct rsvp_head *data = xchg(&tp->root, NULL);
>> - struct rsvp_session **sht;
>> + struct rsvp_head *data = rtnl_dereference(tp->root);
>> int h1, h2;
>>
>> if (data == NULL)
>> return;
>>
>> - sht = data->ht;
>> + RCU_INIT_POINTER(tp->root, NULL);
>>
>> for (h1 = 0; h1 < 256; h1++) {
>> struct rsvp_session *s;
>>
>> - while ((s = sht[h1]) != NULL) {
>> - sht[h1] = s->next;
>> + while ((s = rtnl_dereference(data->ht[h1])) != NULL) {
>> + RCU_INIT_POINTER(data->ht[h1], s->next);
>>
>> for (h2 = 0; h2 <= 16; h2++) {
>> struct rsvp_filter *f;
>>
>> - while ((f = s->ht[h2]) != NULL) {
>> - s->ht[h2] = f->next;
>> + while ((f = rtnl_dereference(s->ht[h2])) != NULL) {
>> + rcu_assign_pointer(s->ht[h2], f->next);
>> rsvp_delete_filter(tp, f);
>> }
>> }
>> - kfree(s);
>> + kfree_rcu(s, rcu);
>> }
>> }
>> - kfree(data);
>> + RCU_INIT_POINTER(tp->root, NULL);
>
> Strange, you already did the RCU_INIT_POINTER(tp->root, NULL) before the
> for(h1 = 0; h1 < 256; h1++) loop
>
Yep, I'll drop this duplicate call.
>
>
>> + kfree_rcu(data, rcu);
>> }
>>
>> static int rsvp_delete(struct tcf_proto *tp, unsigned long arg)
>> {
>> - struct rsvp_filter **fp, *f = (struct rsvp_filter *)arg;
>> + struct rsvp_head *head = rtnl_dereference(tp->root);
>> + struct rsvp_filter *nfp, *f = (struct rsvp_filter *)arg;
>> + struct rsvp_filter __rcu **fp;
>> unsigned int h = f->handle;
>> - struct rsvp_session **sp;
>> - struct rsvp_session *s = f->sess;
>> + struct rsvp_session __rcu **sp;
>> + struct rsvp_session *nsp, *s = f->sess;
>> int i;
>>
>> - for (fp = &s->ht[(h >> 8) & 0xFF]; *fp; fp = &(*fp)->next) {
>> - if (*fp == f) {
>> - tcf_tree_lock(tp);
>> + fp = &s->ht[(h >> 8) & 0xFF];
>> + for (nfp = rtnl_dereference(*fp); nfp;
>> + fp = &nfp->next, nfp = rtnl_dereference(*fp)) {
>> + if (nfp == f) {
>> *fp = f->next;
>
> It seems you do not follow your own convention here ?
>
> RCU_INIT_POINTER(*fp, f->next);
converted both cases to RCU_INIT_POINTER().
Thanks.
--
John Fastabend Intel Corporation
--
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