From 143976ce992fcf3bfc0f4d15d5726bb492dcf262 Mon Sep 17 00:00:00 2001 From: WANG Cong Date: Thu, 24 Aug 2017 16:51:29 -0700 Subject: net_sched: remove tc class reference counting For TC classes, their ->get() and ->put() are always paired, and the reference counting is completely useless, because: 1) For class modification and dumping paths, we already hold RTNL lock, so all of these ->get(),->change(),->put() are atomic. 2) For filter bindiing/unbinding, we use other reference counter than this one, and they should have RTNL lock too. 3) For ->qlen_notify(), it is special because it is called on ->enqueue() path, but we already hold qdisc tree lock there, and we hold this tree lock when graft or delete the class too, so it should not be gone or changed until we release the tree lock. Therefore, this patch removes ->get() and ->put(), but: 1) Adds a new ->find() to find the pointer to a class by classid, no refcnt. 2) Move the original class destroy upon the last refcnt into ->delete(), right after releasing tree lock. This is fine because the class is already removed from hash when holding the lock. For those who also use ->put() as ->unbind(), just rename them to reflect this change. Cc: Jamal Hadi Salim Signed-off-by: Cong Wang Acked-by: Jiri Pirko Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller --- include/net/sch_generic.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'include') diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index 1688f0f6c7ba..d817585aa5df 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -147,8 +147,7 @@ struct Qdisc_class_ops { void (*qlen_notify)(struct Qdisc *, unsigned long); /* Class manipulation routines */ - unsigned long (*get)(struct Qdisc *, u32 classid); - void (*put)(struct Qdisc *, unsigned long); + unsigned long (*find)(struct Qdisc *, u32 classid); int (*change)(struct Qdisc *, u32, u32, struct nlattr **, unsigned long *); int (*delete)(struct Qdisc *, unsigned long); -- cgit v1.2.3 From 3cd904ecbb5d0bcf36dfca7e726bdfd6d3644334 Mon Sep 17 00:00:00 2001 From: WANG Cong Date: Thu, 24 Aug 2017 16:51:30 -0700 Subject: net_sched: kill u32_node pointer in Qdisc It is ugly to hide a u32-filter-specific pointer inside Qdisc, this breaks the TC layers: 1. Qdisc is a generic representation, should not have any specific data of any type 2. Qdisc layer is above filter layer, should only save filters in the list of struct tcf_proto. This pointer is used as the head of the chain of u32 hash tables, that is struct tc_u_hnode, because u32 filter is very special, it allows to create multiple hash tables within one qdisc and across multiple u32 filters. Instead of using this ugly pointer, we can just save it in a global hash table key'ed by (dev ifindex, qdisc handle), therefore we can still treat it as a per qdisc basis data structure conceptually. Of course, because of network namespaces, this key is not unique at all, but it is fine as we already have a pointer to Qdisc in struct tc_u_common, we can just compare the pointers when collision. And this only affects slow paths, has no impact to fast path, thanks to the pointer ->tp_c. Cc: Jamal Hadi Salim Cc: Jiri Pirko Signed-off-by: Cong Wang Acked-by: Jiri Pirko Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller --- include/net/sch_generic.h | 1 - net/sched/cls_u32.c | 57 +++++++++++++++++++++++++++++++++++++++++++---- 2 files changed, 53 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index d817585aa5df..c30b634c5f82 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -75,7 +75,6 @@ struct Qdisc { struct hlist_node hash; u32 handle; u32 parent; - void *u32_node; struct netdev_queue *dev_queue; diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index af22742d2847..99ea4c74dd5b 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -40,6 +40,8 @@ #include #include #include +#include +#include #include #include #include @@ -92,6 +94,7 @@ struct tc_u_common { struct Qdisc *q; int refcnt; u32 hgenerator; + struct hlist_node hnode; struct rcu_head rcu; }; @@ -323,12 +326,40 @@ static u32 gen_new_htid(struct tc_u_common *tp_c) return i > 0 ? (tp_c->hgenerator|0x800)<<20 : 0; } +static struct hlist_head *tc_u_common_hash; + +#define U32_HASH_SHIFT 10 +#define U32_HASH_SIZE (1 << U32_HASH_SHIFT) + +static unsigned int tc_u_hash(const struct tcf_proto *tp) +{ + struct net_device *dev = tp->q->dev_queue->dev; + u32 qhandle = tp->q->handle; + int ifindex = dev->ifindex; + + return hash_64((u64)ifindex << 32 | qhandle, U32_HASH_SHIFT); +} + +static struct tc_u_common *tc_u_common_find(const struct tcf_proto *tp) +{ + struct tc_u_common *tc; + unsigned int h; + + h = tc_u_hash(tp); + hlist_for_each_entry(tc, &tc_u_common_hash[h], hnode) { + if (tc->q == tp->q) + return tc; + } + return NULL; +} + static int u32_init(struct tcf_proto *tp) { struct tc_u_hnode *root_ht; struct tc_u_common *tp_c; + unsigned int h; - tp_c = tp->q->u32_node; + tp_c = tc_u_common_find(tp); root_ht = kzalloc(sizeof(*root_ht), GFP_KERNEL); if (root_ht == NULL) @@ -345,7 +376,10 @@ static int u32_init(struct tcf_proto *tp) return -ENOBUFS; } tp_c->q = tp->q; - tp->q->u32_node = tp_c; + INIT_HLIST_NODE(&tp_c->hnode); + + h = tc_u_hash(tp); + hlist_add_head(&tp_c->hnode, &tc_u_common_hash[h]); } tp_c->refcnt++; @@ -585,7 +619,7 @@ static void u32_destroy(struct tcf_proto *tp) if (--tp_c->refcnt == 0) { struct tc_u_hnode *ht; - tp->q->u32_node = NULL; + hlist_del(&tp_c->hnode); for (ht = rtnl_dereference(tp_c->hlist); ht; @@ -1213,6 +1247,8 @@ static struct tcf_proto_ops cls_u32_ops __read_mostly = { static int __init init_u32(void) { + int i, ret; + pr_info("u32 classifier\n"); #ifdef CONFIG_CLS_U32_PERF pr_info(" Performance counters on\n"); @@ -1223,12 +1259,25 @@ static int __init init_u32(void) #ifdef CONFIG_NET_CLS_ACT pr_info(" Actions configured\n"); #endif - return register_tcf_proto_ops(&cls_u32_ops); + tc_u_common_hash = kvmalloc_array(U32_HASH_SIZE, + sizeof(struct hlist_head), + GFP_KERNEL); + if (!tc_u_common_hash) + return -ENOMEM; + + for (i = 0; i < U32_HASH_SIZE; i++) + INIT_HLIST_HEAD(&tc_u_common_hash[i]); + + ret = register_tcf_proto_ops(&cls_u32_ops); + if (ret) + kvfree(tc_u_common_hash); + return ret; } static void __exit exit_u32(void) { unregister_tcf_proto_ops(&cls_u32_ops); + kvfree(tc_u_common_hash); } module_init(init_u32) -- cgit v1.2.3