flow: virtualize flow cache entry methods
This allows to validate the cached object before returning it.
It also allows to destruct object properly, if the last reference
was held in flow cache. This is also a prepartion for caching
bundles in the flow cache.
In return for virtualizing the methods, we save on:
- not having to regenerate the whole flow cache on policy removal:
each flow matching a killed policy gets refreshed as the getter
function notices it smartly.
- we do not have to call flow_cache_flush from policy gc, since the
flow cache now properly deletes the object if it had any references
Signed-off-by: Timo Teras <timo.teras@iki.fi>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/flow.c b/net/core/flow.c
index 1d27ca6..521df52 100644
--- a/net/core/flow.c
+++ b/net/core/flow.c
@@ -26,17 +26,16 @@
#include <linux/security.h>
struct flow_cache_entry {
- struct flow_cache_entry *next;
- u16 family;
- u8 dir;
- u32 genid;
- struct flowi key;
- void *object;
- atomic_t *object_ref;
+ struct flow_cache_entry *next;
+ u16 family;
+ u8 dir;
+ u32 genid;
+ struct flowi key;
+ struct flow_cache_object *object;
};
struct flow_cache_percpu {
- struct flow_cache_entry ** hash_table;
+ struct flow_cache_entry **hash_table;
int hash_count;
u32 hash_rnd;
int hash_rnd_recalc;
@@ -44,7 +43,7 @@
};
struct flow_flush_info {
- struct flow_cache * cache;
+ struct flow_cache *cache;
atomic_t cpuleft;
struct completion completion;
};
@@ -52,7 +51,7 @@
struct flow_cache {
u32 hash_shift;
unsigned long order;
- struct flow_cache_percpu * percpu;
+ struct flow_cache_percpu *percpu;
struct notifier_block hotcpu_notifier;
int low_watermark;
int high_watermark;
@@ -78,12 +77,21 @@
add_timer(&fc->rnd_timer);
}
+static int flow_entry_valid(struct flow_cache_entry *fle)
+{
+ if (atomic_read(&flow_cache_genid) != fle->genid)
+ return 0;
+ if (fle->object && !fle->object->ops->check(fle->object))
+ return 0;
+ return 1;
+}
+
static void flow_entry_kill(struct flow_cache *fc,
struct flow_cache_percpu *fcp,
struct flow_cache_entry *fle)
{
if (fle->object)
- atomic_dec(fle->object_ref);
+ fle->object->ops->delete(fle->object);
kmem_cache_free(flow_cachep, fle);
fcp->hash_count--;
}
@@ -96,16 +104,18 @@
int i;
for (i = 0; i < flow_cache_hash_size(fc); i++) {
- int k = 0;
+ int saved = 0;
flp = &fcp->hash_table[i];
- while ((fle = *flp) != NULL && k < shrink_to) {
- k++;
- flp = &fle->next;
- }
while ((fle = *flp) != NULL) {
- *flp = fle->next;
- flow_entry_kill(fc, fcp, fle);
+ if (saved < shrink_to &&
+ flow_entry_valid(fle)) {
+ saved++;
+ flp = &fle->next;
+ } else {
+ *flp = fle->next;
+ flow_entry_kill(fc, fcp, fle);
+ }
}
}
}
@@ -166,18 +176,21 @@
return 0;
}
-void *flow_cache_lookup(struct net *net, struct flowi *key, u16 family, u8 dir,
- flow_resolve_t resolver)
+struct flow_cache_object *
+flow_cache_lookup(struct net *net, struct flowi *key, u16 family, u8 dir,
+ flow_resolve_t resolver, void *ctx)
{
struct flow_cache *fc = &flow_cache_global;
struct flow_cache_percpu *fcp;
struct flow_cache_entry *fle, **head;
+ struct flow_cache_object *flo;
unsigned int hash;
local_bh_disable();
fcp = per_cpu_ptr(fc->percpu, smp_processor_id());
fle = NULL;
+ flo = NULL;
/* Packet really early in init? Making flow_cache_init a
* pre-smp initcall would solve this. --RR */
if (!fcp->hash_table)
@@ -185,27 +198,17 @@
if (fcp->hash_rnd_recalc)
flow_new_hash_rnd(fc, fcp);
- hash = flow_hash_code(fc, fcp, key);
+ hash = flow_hash_code(fc, fcp, key);
head = &fcp->hash_table[hash];
for (fle = *head; fle; fle = fle->next) {
if (fle->family == family &&
fle->dir == dir &&
- flow_key_compare(key, &fle->key) == 0) {
- if (fle->genid == atomic_read(&flow_cache_genid)) {
- void *ret = fle->object;
-
- if (ret)
- atomic_inc(fle->object_ref);
- local_bh_enable();
-
- return ret;
- }
+ flow_key_compare(key, &fle->key) == 0)
break;
- }
}
- if (!fle) {
+ if (unlikely(!fle)) {
if (fcp->hash_count > fc->high_watermark)
flow_cache_shrink(fc, fcp);
@@ -219,33 +222,39 @@
fle->object = NULL;
fcp->hash_count++;
}
+ } else if (likely(fle->genid == atomic_read(&flow_cache_genid))) {
+ flo = fle->object;
+ if (!flo)
+ goto ret_object;
+ flo = flo->ops->get(flo);
+ if (flo)
+ goto ret_object;
+ } else if (fle->object) {
+ flo = fle->object;
+ flo->ops->delete(flo);
+ fle->object = NULL;
}
nocache:
- {
- int err;
- void *obj;
- atomic_t *obj_ref;
-
- err = resolver(net, key, family, dir, &obj, &obj_ref);
-
- if (fle && !err) {
- fle->genid = atomic_read(&flow_cache_genid);
-
- if (fle->object)
- atomic_dec(fle->object_ref);
-
- fle->object = obj;
- fle->object_ref = obj_ref;
- if (obj)
- atomic_inc(fle->object_ref);
- }
- local_bh_enable();
-
- if (err)
- obj = ERR_PTR(err);
- return obj;
+ flo = NULL;
+ if (fle) {
+ flo = fle->object;
+ fle->object = NULL;
}
+ flo = resolver(net, key, family, dir, flo, ctx);
+ if (fle) {
+ fle->genid = atomic_read(&flow_cache_genid);
+ if (!IS_ERR(flo))
+ fle->object = flo;
+ else
+ fle->genid--;
+ } else {
+ if (flo && !IS_ERR(flo))
+ flo->ops->delete(flo);
+ }
+ret_object:
+ local_bh_enable();
+ return flo;
}
static void flow_cache_flush_tasklet(unsigned long data)
@@ -261,13 +270,12 @@
fle = fcp->hash_table[i];
for (; fle; fle = fle->next) {
- unsigned genid = atomic_read(&flow_cache_genid);
-
- if (!fle->object || fle->genid == genid)
+ if (flow_entry_valid(fle))
continue;
+ if (fle->object)
+ fle->object->ops->delete(fle->object);
fle->object = NULL;
- atomic_dec(fle->object_ref);
}
}
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 82789cf..7722bae 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -216,6 +216,35 @@
xfrm_pol_put(xp);
}
+static struct flow_cache_object *xfrm_policy_flo_get(struct flow_cache_object *flo)
+{
+ struct xfrm_policy *pol = container_of(flo, struct xfrm_policy, flo);
+
+ if (unlikely(pol->walk.dead))
+ flo = NULL;
+ else
+ xfrm_pol_hold(pol);
+
+ return flo;
+}
+
+static int xfrm_policy_flo_check(struct flow_cache_object *flo)
+{
+ struct xfrm_policy *pol = container_of(flo, struct xfrm_policy, flo);
+
+ return !pol->walk.dead;
+}
+
+static void xfrm_policy_flo_delete(struct flow_cache_object *flo)
+{
+ xfrm_pol_put(container_of(flo, struct xfrm_policy, flo));
+}
+
+static const struct flow_cache_ops xfrm_policy_fc_ops = {
+ .get = xfrm_policy_flo_get,
+ .check = xfrm_policy_flo_check,
+ .delete = xfrm_policy_flo_delete,
+};
/* Allocate xfrm_policy. Not used here, it is supposed to be used by pfkeyv2
* SPD calls.
@@ -236,6 +265,7 @@
atomic_set(&policy->refcnt, 1);
setup_timer(&policy->timer, xfrm_policy_timer,
(unsigned long)policy);
+ policy->flo.ops = &xfrm_policy_fc_ops;
}
return policy;
}
@@ -269,9 +299,6 @@
if (del_timer(&policy->timer))
atomic_dec(&policy->refcnt);
- if (atomic_read(&policy->refcnt) > 1)
- flow_cache_flush();
-
xfrm_pol_put(policy);
}
@@ -661,10 +688,8 @@
}
write_unlock_bh(&xfrm_policy_lock);
- if (ret && delete) {
- atomic_inc(&flow_cache_genid);
+ if (ret && delete)
xfrm_policy_kill(ret);
- }
return ret;
}
EXPORT_SYMBOL(xfrm_policy_bysel_ctx);
@@ -703,10 +728,8 @@
}
write_unlock_bh(&xfrm_policy_lock);
- if (ret && delete) {
- atomic_inc(&flow_cache_genid);
+ if (ret && delete)
xfrm_policy_kill(ret);
- }
return ret;
}
EXPORT_SYMBOL(xfrm_policy_byid);
@@ -822,7 +845,6 @@
}
if (!cnt)
err = -ESRCH;
- atomic_inc(&flow_cache_genid);
out:
write_unlock_bh(&xfrm_policy_lock);
return err;
@@ -976,32 +998,35 @@
return ret;
}
-static int xfrm_policy_lookup(struct net *net, struct flowi *fl, u16 family,
- u8 dir, void **objp, atomic_t **obj_refp)
+static struct flow_cache_object *
+xfrm_policy_lookup(struct net *net, struct flowi *fl, u16 family,
+ u8 dir, struct flow_cache_object *old_obj, void *ctx)
{
struct xfrm_policy *pol;
- int err = 0;
+
+ if (old_obj)
+ xfrm_pol_put(container_of(old_obj, struct xfrm_policy, flo));
#ifdef CONFIG_XFRM_SUB_POLICY
pol = xfrm_policy_lookup_bytype(net, XFRM_POLICY_TYPE_SUB, fl, family, dir);
- if (IS_ERR(pol)) {
- err = PTR_ERR(pol);
- pol = NULL;
- }
- if (pol || err)
- goto end;
+ if (IS_ERR(pol))
+ return ERR_CAST(pol);
+ if (pol)
+ goto found;
#endif
pol = xfrm_policy_lookup_bytype(net, XFRM_POLICY_TYPE_MAIN, fl, family, dir);
- if (IS_ERR(pol)) {
- err = PTR_ERR(pol);
- pol = NULL;
- }
-#ifdef CONFIG_XFRM_SUB_POLICY
-end:
-#endif
- if ((*objp = (void *) pol) != NULL)
- *obj_refp = &pol->refcnt;
- return err;
+ if (IS_ERR(pol))
+ return ERR_CAST(pol);
+ if (pol)
+ goto found;
+ return NULL;
+
+found:
+ /* Resolver returns two references:
+ * one for cache and one for caller of flow_cache_lookup() */
+ xfrm_pol_hold(pol);
+
+ return &pol->flo;
}
static inline int policy_to_flow_dir(int dir)
@@ -1091,8 +1116,6 @@
pol = __xfrm_policy_unlink(pol, dir);
write_unlock_bh(&xfrm_policy_lock);
if (pol) {
- if (dir < XFRM_POLICY_MAX)
- atomic_inc(&flow_cache_genid);
xfrm_policy_kill(pol);
return 0;
}
@@ -1578,18 +1601,24 @@
}
if (!policy) {
+ struct flow_cache_object *flo;
+
/* To accelerate a bit... */
if ((dst_orig->flags & DST_NOXFRM) ||
!net->xfrm.policy_count[XFRM_POLICY_OUT])
goto nopol;
- policy = flow_cache_lookup(net, fl, dst_orig->ops->family,
- dir, xfrm_policy_lookup);
- err = PTR_ERR(policy);
- if (IS_ERR(policy)) {
+ flo = flow_cache_lookup(net, fl, dst_orig->ops->family,
+ dir, xfrm_policy_lookup, NULL);
+ err = PTR_ERR(flo);
+ if (IS_ERR(flo)) {
XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTPOLERROR);
goto dropdst;
}
+ if (flo)
+ policy = container_of(flo, struct xfrm_policy, flo);
+ else
+ policy = NULL;
}
if (!policy)
@@ -1939,9 +1968,16 @@
}
}
- if (!pol)
- pol = flow_cache_lookup(net, &fl, family, fl_dir,
- xfrm_policy_lookup);
+ if (!pol) {
+ struct flow_cache_object *flo;
+
+ flo = flow_cache_lookup(net, &fl, family, fl_dir,
+ xfrm_policy_lookup, NULL);
+ if (IS_ERR_OR_NULL(flo))
+ pol = ERR_CAST(flo);
+ else
+ pol = container_of(flo, struct xfrm_policy, flo);
+ }
if (IS_ERR(pol)) {
XFRM_INC_STATS(net, LINUX_MIB_XFRMINPOLERROR);