net: sched: RCU cls_route
RCUify the route classifier. For now however spinlock's are used to
protect fastmap cache.
The issue here is the fastmap may be read by one CPU while the
cache is being updated by another. An array of pointers could be
one possible solution.
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
index dd9fc25..ba96dea 100644
--- a/net/sched/cls_route.c
+++ b/net/sched/cls_route.c
@@ -29,25 +29,26 @@
* are mutually exclusive.
* 3. "to TAG from ANY" has higher priority, than "to ANY from XXX"
*/
-
struct route4_fastmap {
- struct route4_filter *filter;
- u32 id;
- int iif;
+ struct route4_filter *filter;
+ u32 id;
+ int iif;
};
struct route4_head {
- struct route4_fastmap fastmap[16];
- struct route4_bucket *table[256 + 1];
+ struct route4_fastmap fastmap[16];
+ struct route4_bucket __rcu *table[256 + 1];
+ struct rcu_head rcu;
};
struct route4_bucket {
/* 16 FROM buckets + 16 IIF buckets + 1 wildcard bucket */
- struct route4_filter *ht[16 + 16 + 1];
+ struct route4_filter __rcu *ht[16 + 16 + 1];
+ struct rcu_head rcu;
};
struct route4_filter {
- struct route4_filter *next;
+ struct route4_filter __rcu *next;
u32 id;
int iif;
@@ -55,6 +56,8 @@
struct tcf_exts exts;
u32 handle;
struct route4_bucket *bkt;
+ struct tcf_proto *tp;
+ struct rcu_head rcu;
};
#define ROUTE4_FAILURE ((struct route4_filter *)(-1L))
@@ -64,14 +67,13 @@
return id & 0xF;
}
+static DEFINE_SPINLOCK(fastmap_lock);
static void
-route4_reset_fastmap(struct Qdisc *q, struct route4_head *head, u32 id)
+route4_reset_fastmap(struct route4_head *head)
{
- spinlock_t *root_lock = qdisc_root_sleeping_lock(q);
-
- spin_lock_bh(root_lock);
+ spin_lock_bh(&fastmap_lock);
memset(head->fastmap, 0, sizeof(head->fastmap));
- spin_unlock_bh(root_lock);
+ spin_unlock_bh(&fastmap_lock);
}
static void
@@ -80,9 +82,12 @@
{
int h = route4_fastmap_hash(id, iif);
+ /* fastmap updates must look atomic to aling id, iff, filter */
+ spin_lock_bh(&fastmap_lock);
head->fastmap[h].id = id;
head->fastmap[h].iif = iif;
head->fastmap[h].filter = f;
+ spin_unlock_bh(&fastmap_lock);
}
static inline int route4_hash_to(u32 id)
@@ -123,7 +128,7 @@
static int route4_classify(struct sk_buff *skb, const struct tcf_proto *tp,
struct tcf_result *res)
{
- struct route4_head *head = tp->root;
+ struct route4_head *head = rcu_dereference_bh(tp->root);
struct dst_entry *dst;
struct route4_bucket *b;
struct route4_filter *f;
@@ -141,32 +146,43 @@
iif = inet_iif(skb);
h = route4_fastmap_hash(id, iif);
+
+ spin_lock(&fastmap_lock);
if (id == head->fastmap[h].id &&
iif == head->fastmap[h].iif &&
(f = head->fastmap[h].filter) != NULL) {
- if (f == ROUTE4_FAILURE)
+ if (f == ROUTE4_FAILURE) {
+ spin_unlock(&fastmap_lock);
goto failure;
+ }
*res = f->res;
+ spin_unlock(&fastmap_lock);
return 0;
}
+ spin_unlock(&fastmap_lock);
h = route4_hash_to(id);
restart:
- b = head->table[h];
+ b = rcu_dereference_bh(head->table[h]);
if (b) {
- for (f = b->ht[route4_hash_from(id)]; f; f = f->next)
+ for (f = rcu_dereference_bh(b->ht[route4_hash_from(id)]);
+ f;
+ f = rcu_dereference_bh(f->next))
if (f->id == id)
ROUTE4_APPLY_RESULT();
- for (f = b->ht[route4_hash_iif(iif)]; f; f = f->next)
+ for (f = rcu_dereference_bh(b->ht[route4_hash_iif(iif)]);
+ f;
+ f = rcu_dereference_bh(f->next))
if (f->iif == iif)
ROUTE4_APPLY_RESULT();
- for (f = b->ht[route4_hash_wild()]; f; f = f->next)
+ for (f = rcu_dereference_bh(b->ht[route4_hash_wild()]);
+ f;
+ f = rcu_dereference_bh(f->next))
ROUTE4_APPLY_RESULT();
-
}
if (h < 256) {
h = 256;
@@ -213,7 +229,7 @@
static unsigned long route4_get(struct tcf_proto *tp, u32 handle)
{
- struct route4_head *head = tp->root;
+ struct route4_head *head = rtnl_dereference(tp->root);
struct route4_bucket *b;
struct route4_filter *f;
unsigned int h1, h2;
@@ -229,9 +245,11 @@
if (h2 > 32)
return 0;
- b = head->table[h1];
+ b = rtnl_dereference(head->table[h1]);
if (b) {
- for (f = b->ht[h2]; f; f = f->next)
+ for (f = rtnl_dereference(b->ht[h2]);
+ f;
+ f = rtnl_dereference(f->next))
if (f->handle == handle)
return (unsigned long)f;
}
@@ -248,8 +266,11 @@
}
static void
-route4_delete_filter(struct tcf_proto *tp, struct route4_filter *f)
+route4_delete_filter(struct rcu_head *head)
{
+ struct route4_filter *f = container_of(head, struct route4_filter, rcu);
+ struct tcf_proto *tp = f->tp;
+
tcf_unbind_filter(tp, &f->res);
tcf_exts_destroy(tp, &f->exts);
kfree(f);
@@ -257,7 +278,7 @@
static void route4_destroy(struct tcf_proto *tp)
{
- struct route4_head *head = tp->root;
+ struct route4_head *head = rtnl_dereference(tp->root);
int h1, h2;
if (head == NULL)
@@ -266,28 +287,35 @@
for (h1 = 0; h1 <= 256; h1++) {
struct route4_bucket *b;
- b = head->table[h1];
+ b = rtnl_dereference(head->table[h1]);
if (b) {
for (h2 = 0; h2 <= 32; h2++) {
struct route4_filter *f;
- while ((f = b->ht[h2]) != NULL) {
- b->ht[h2] = f->next;
- route4_delete_filter(tp, f);
+ while ((f = rtnl_dereference(b->ht[h2])) != NULL) {
+ struct route4_filter *next;
+
+ next = rtnl_dereference(f->next);
+ RCU_INIT_POINTER(b->ht[h2], next);
+ call_rcu(&f->rcu, route4_delete_filter);
}
}
- kfree(b);
+ RCU_INIT_POINTER(head->table[h1], NULL);
+ kfree_rcu(b, rcu);
}
}
- kfree(head);
+ RCU_INIT_POINTER(tp->root, NULL);
+ kfree_rcu(head, rcu);
}
static int route4_delete(struct tcf_proto *tp, unsigned long arg)
{
- struct route4_head *head = tp->root;
- struct route4_filter **fp, *f = (struct route4_filter *)arg;
- unsigned int h = 0;
+ struct route4_head *head = rtnl_dereference(tp->root);
+ struct route4_filter *f = (struct route4_filter *)arg;
+ struct route4_filter __rcu **fp;
+ struct route4_filter *nf;
struct route4_bucket *b;
+ unsigned int h = 0;
int i;
if (!head || !f)
@@ -296,27 +324,35 @@
h = f->handle;
b = f->bkt;
- for (fp = &b->ht[from_hash(h >> 16)]; *fp; fp = &(*fp)->next) {
- if (*fp == f) {
- tcf_tree_lock(tp);
- *fp = f->next;
- tcf_tree_unlock(tp);
+ fp = &b->ht[from_hash(h >> 16)];
+ for (nf = rtnl_dereference(*fp); nf;
+ fp = &nf->next, nf = rtnl_dereference(*fp)) {
+ if (nf == f) {
+ /* unlink it */
+ RCU_INIT_POINTER(*fp, rtnl_dereference(f->next));
- route4_reset_fastmap(tp->q, head, f->id);
- route4_delete_filter(tp, f);
+ /* Remove any fastmap lookups that might ref filter
+ * notice we unlink'd the filter so we can't get it
+ * back in the fastmap.
+ */
+ route4_reset_fastmap(head);
- /* Strip tree */
+ /* Delete it */
+ call_rcu(&f->rcu, route4_delete_filter);
- for (i = 0; i <= 32; i++)
- if (b->ht[i])
+ /* Strip RTNL protected tree */
+ for (i = 0; i <= 32; i++) {
+ struct route4_filter *rt;
+
+ rt = rtnl_dereference(b->ht[i]);
+ if (rt)
return 0;
+ }
/* OK, session has no flows */
- tcf_tree_lock(tp);
- head->table[to_hash(h)] = NULL;
- tcf_tree_unlock(tp);
+ RCU_INIT_POINTER(head->table[to_hash(h)], NULL);
+ kfree_rcu(b, rcu);
- kfree(b);
return 0;
}
}
@@ -380,26 +416,25 @@
}
h1 = to_hash(nhandle);
- b = head->table[h1];
+ b = rtnl_dereference(head->table[h1]);
if (!b) {
err = -ENOBUFS;
b = kzalloc(sizeof(struct route4_bucket), GFP_KERNEL);
if (b == NULL)
goto errout;
- tcf_tree_lock(tp);
- head->table[h1] = b;
- tcf_tree_unlock(tp);
+ rcu_assign_pointer(head->table[h1], b);
} else {
unsigned int h2 = from_hash(nhandle >> 16);
err = -EEXIST;
- for (fp = b->ht[h2]; fp; fp = fp->next)
+ for (fp = rtnl_dereference(b->ht[h2]);
+ fp;
+ fp = rtnl_dereference(fp->next))
if (fp->handle == f->handle)
goto errout;
}
- tcf_tree_lock(tp);
if (tb[TCA_ROUTE4_TO])
f->id = to;
@@ -410,7 +445,7 @@
f->handle = nhandle;
f->bkt = b;
- tcf_tree_unlock(tp);
+ f->tp = tp;
if (tb[TCA_ROUTE4_CLASSID]) {
f->res.classid = nla_get_u32(tb[TCA_ROUTE4_CLASSID]);
@@ -431,14 +466,15 @@
struct nlattr **tca,
unsigned long *arg, bool ovr)
{
- struct route4_head *head = tp->root;
- struct route4_filter *f, *f1, **fp;
+ struct route4_head *head = rtnl_dereference(tp->root);
+ struct route4_filter __rcu **fp;
+ struct route4_filter *fold, *f1, *pfp, *f = NULL;
struct route4_bucket *b;
struct nlattr *opt = tca[TCA_OPTIONS];
struct nlattr *tb[TCA_ROUTE4_MAX + 1];
unsigned int h, th;
- u32 old_handle = 0;
int err;
+ bool new = true;
if (opt == NULL)
return handle ? -EINVAL : 0;
@@ -447,70 +483,70 @@
if (err < 0)
return err;
- f = (struct route4_filter *)*arg;
- if (f) {
- if (f->handle != handle && handle)
+ fold = (struct route4_filter *)*arg;
+ if (fold && handle && fold->handle != handle)
return -EINVAL;
- if (f->bkt)
- old_handle = f->handle;
-
- err = route4_set_parms(net, tp, base, f, handle, head, tb,
- tca[TCA_RATE], 0, ovr);
- if (err < 0)
- return err;
-
- goto reinsert;
- }
-
err = -ENOBUFS;
if (head == NULL) {
head = kzalloc(sizeof(struct route4_head), GFP_KERNEL);
if (head == NULL)
goto errout;
-
- tcf_tree_lock(tp);
- tp->root = head;
- tcf_tree_unlock(tp);
+ rcu_assign_pointer(tp->root, head);
}
f = kzalloc(sizeof(struct route4_filter), GFP_KERNEL);
- if (f == NULL)
+ if (!f)
goto errout;
tcf_exts_init(&f->exts, TCA_ROUTE4_ACT, TCA_ROUTE4_POLICE);
+ if (fold) {
+ f->id = fold->id;
+ f->iif = fold->iif;
+ f->res = fold->res;
+ f->handle = fold->handle;
+
+ f->tp = fold->tp;
+ f->bkt = fold->bkt;
+ new = false;
+ }
+
err = route4_set_parms(net, tp, base, f, handle, head, tb,
- tca[TCA_RATE], 1, ovr);
+ tca[TCA_RATE], new, ovr);
if (err < 0)
goto errout;
-reinsert:
h = from_hash(f->handle >> 16);
- for (fp = &f->bkt->ht[h]; (f1 = *fp) != NULL; fp = &f1->next)
+ fp = &f->bkt->ht[h];
+ for (pfp = rtnl_dereference(*fp);
+ (f1 = rtnl_dereference(*fp)) != NULL;
+ fp = &f1->next)
if (f->handle < f1->handle)
break;
- f->next = f1;
- tcf_tree_lock(tp);
- *fp = f;
+ rcu_assign_pointer(f->next, f1);
+ rcu_assign_pointer(*fp, f);
- if (old_handle && f->handle != old_handle) {
- th = to_hash(old_handle);
- h = from_hash(old_handle >> 16);
- b = head->table[th];
+ if (fold && fold->handle && f->handle != fold->handle) {
+ th = to_hash(fold->handle);
+ h = from_hash(fold->handle >> 16);
+ b = rtnl_dereference(head->table[th]);
if (b) {
- for (fp = &b->ht[h]; *fp; fp = &(*fp)->next) {
- if (*fp == f) {
+ fp = &b->ht[h];
+ for (pfp = rtnl_dereference(*fp); pfp;
+ fp = &pfp->next, pfp = rtnl_dereference(*fp)) {
+ if (pfp == f) {
*fp = f->next;
break;
}
}
}
}
- tcf_tree_unlock(tp);
- route4_reset_fastmap(tp->q, head, f->id);
+ route4_reset_fastmap(head);
*arg = (unsigned long)f;
+ if (fold)
+ call_rcu(&fold->rcu, route4_delete_filter);
return 0;
errout:
@@ -520,7 +556,7 @@
static void route4_walk(struct tcf_proto *tp, struct tcf_walker *arg)
{
- struct route4_head *head = tp->root;
+ struct route4_head *head = rtnl_dereference(tp->root);
unsigned int h, h1;
if (head == NULL)
@@ -530,13 +566,15 @@
return;
for (h = 0; h <= 256; h++) {
- struct route4_bucket *b = head->table[h];
+ struct route4_bucket *b = rtnl_dereference(head->table[h]);
if (b) {
for (h1 = 0; h1 <= 32; h1++) {
struct route4_filter *f;
- for (f = b->ht[h1]; f; f = f->next) {
+ for (f = rtnl_dereference(b->ht[h1]);
+ f;
+ f = rtnl_dereference(f->next)) {
if (arg->count < arg->skip) {
arg->count++;
continue;