diff mbox series

[net-next,v4,4/6] Convert neighbour iteration to use hlist+macro

Message ID 20241015165929.3203216-5-gnaaman@drivenets.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series Improve neigh_flush_dev performance | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next, async
netdev/apply fail Patch does not apply to net-next-1

Commit Message

Gilad Naaman Oct. 15, 2024, 4:59 p.m. UTC 
Remove all usage of the bare neighbour::next pointer,
replacing them with neighbour::hash and its for_each macro.

Signed-off-by: Gilad Naaman <gnaaman@drivenets.com>
---
 include/net/neighbour.h |  7 +++----
 net/core/neighbour.c    | 29 +++++++++++------------------
 2 files changed, 14 insertions(+), 22 deletions(-)

Comments

Kuniyuki Iwashima Oct. 15, 2024, 11:38 p.m. UTC | #1 
From: Gilad Naaman <gnaaman@drivenets.com>
Date: Tue, 15 Oct 2024 16:59:24 +0000
> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index 4bdf7649ca57..cca524a55c97 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -391,8 +391,7 @@ static void neigh_flush_dev(struct neigh_table *tbl, struct net_device *dev,
>  		struct neighbour *n;
>  		struct neighbour __rcu **np = &nht->hash_buckets[i];
>  
> -		while ((n = rcu_dereference_protected(*np,
> -					lockdep_is_held(&tbl->lock))) != NULL) {
> +		neigh_for_each(n, &nht->hash_heads[i]) {
>  			if (dev && n->dev != dev) {
>  				np = &n->next;
>  				continue;
> @@ -427,6 +426,7 @@ static void neigh_flush_dev(struct neigh_table *tbl, struct net_device *dev,
>  					n->nud_state = NUD_NONE;
>  				neigh_dbg(2, "neigh %p is stray\n", n);
>  			}
> +			np = &n->next;
>  			write_unlock(&n->lock);
>  			neigh_cleanup_and_release(n);
>  		}

Is this chunk necessary ?


> @@ -976,6 +970,7 @@ static void neigh_periodic_work(struct work_struct *work)
>  {
>  	struct neigh_table *tbl = container_of(work, struct neigh_table, gc_work.work);
>  	struct neighbour *n;
> +	struct hlist_node *tmp;
>  	struct neighbour __rcu **np;
>  	unsigned int i;
>  	struct neigh_hash_table *nht;

nit: let's sort variables in reverse xmas tree order.



> @@ -3124,11 +3117,11 @@ void __neigh_for_each_release(struct neigh_table *tbl,
>  					lockdep_is_held(&tbl->lock));
>  	for (chain = 0; chain < (1 << nht->hash_shift); chain++) {
>  		struct neighbour *n;
> +		struct hlist_node *tmp;
>  		struct neighbour __rcu **np;

nit: reverse xmas tree order.


>  
>  		np = &nht->hash_buckets[chain];
> -		while ((n = rcu_dereference_protected(*np,
> -					lockdep_is_held(&tbl->lock))) != NULL) {
> +		neigh_for_each_safe(n, tmp, &nht->hash_heads[chain]) {
>  			int release;
>  
>  			write_lock(&n->lock);
> -- 
> 2.46.0
Gilad Naaman Oct. 16, 2024, 9:18 a.m. UTC | #2 
> > @@ -427,6 +426,7 @@ static void neigh_flush_dev(struct neigh_table *tbl, struct net_device *dev,
> >  					n->nud_state = NUD_NONE;
> >  				neigh_dbg(2, "neigh %p is stray\n", n);
> >  			}
> > +			np = &n->next;
> >  			write_unlock(&n->lock);
> >  			neigh_cleanup_and_release(n);
> >  		}
> 
> Is this chunk necessary ?

Apologies, you're right.

I mixed up skipping with regular loop maintnance,
and thought I need to compensate for removing the original loop logic.
Obviously wrong in retrospect.
diff mbox series

Patch

diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 7dc0d4d6a4a8..c0c35a15d2ad 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -279,6 +279,8 @@  static inline void *neighbour_priv(const struct neighbour *n)
 extern const struct nla_policy nda_policy[];
 
 #define neigh_for_each(pos, head) hlist_for_each_entry(pos, head, hash)
+#define neigh_for_each_safe(pos, tmp, head) hlist_for_each_entry_safe(pos, tmp, head, hash)
+
 #define neigh_hlist_entry(n) hlist_entry_safe(n, struct neighbour, hash)
 #define neigh_first_rcu(bucket) \
 	neigh_hlist_entry(rcu_dereference(hlist_first_rcu(bucket)))
@@ -312,12 +314,9 @@  static inline struct neighbour *___neigh_lookup_noref(
 	u32 hash_val;
 
 	hash_val = hash(pkey, dev, nht->hash_rnd) >> (32 - nht->hash_shift);
-	for (n = rcu_dereference(nht->hash_buckets[hash_val]);
-	     n != NULL;
-	     n = rcu_dereference(n->next)) {
+	neigh_for_each(n, &nht->hash_heads[hash_val])
 		if (n->dev == dev && key_eq(n, pkey))
 			return n;
-	}
 
 	return NULL;
 }
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 4bdf7649ca57..cca524a55c97 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -391,8 +391,7 @@  static void neigh_flush_dev(struct neigh_table *tbl, struct net_device *dev,
 		struct neighbour *n;
 		struct neighbour __rcu **np = &nht->hash_buckets[i];
 
-		while ((n = rcu_dereference_protected(*np,
-					lockdep_is_held(&tbl->lock))) != NULL) {
+		neigh_for_each(n, &nht->hash_heads[i]) {
 			if (dev && n->dev != dev) {
 				np = &n->next;
 				continue;
@@ -427,6 +426,7 @@  static void neigh_flush_dev(struct neigh_table *tbl, struct net_device *dev,
 					n->nud_state = NUD_NONE;
 				neigh_dbg(2, "neigh %p is stray\n", n);
 			}
+			np = &n->next;
 			write_unlock(&n->lock);
 			neigh_cleanup_and_release(n);
 		}
@@ -614,11 +614,9 @@  static struct neigh_hash_table *neigh_hash_grow(struct neigh_table *tbl,
 
 	for (i = 0; i < (1 << old_nht->hash_shift); i++) {
 		struct neighbour *n, *next;
+		struct hlist_node *tmp;
 
-		for (n = rcu_dereference_protected(old_nht->hash_buckets[i],
-						   lockdep_is_held(&tbl->lock));
-		     n != NULL;
-		     n = next) {
+		neigh_for_each_safe(n, tmp, &old_nht->hash_heads[i]) {
 			hash = tbl->hash(n->primary_key, n->dev,
 					 new_nht->hash_rnd);
 
@@ -719,11 +717,7 @@  ___neigh_create(struct neigh_table *tbl, const void *pkey,
 		goto out_tbl_unlock;
 	}
 
-	for (n1 = rcu_dereference_protected(nht->hash_buckets[hash_val],
-					    lockdep_is_held(&tbl->lock));
-	     n1 != NULL;
-	     n1 = rcu_dereference_protected(n1->next,
-			lockdep_is_held(&tbl->lock))) {
+	neigh_for_each(n1, &nht->hash_heads[hash_val]) {
 		if (dev == n1->dev && !memcmp(n1->primary_key, n->primary_key, key_len)) {
 			if (want_ref)
 				neigh_hold(n1);
@@ -976,6 +970,7 @@  static void neigh_periodic_work(struct work_struct *work)
 {
 	struct neigh_table *tbl = container_of(work, struct neigh_table, gc_work.work);
 	struct neighbour *n;
+	struct hlist_node *tmp;
 	struct neighbour __rcu **np;
 	unsigned int i;
 	struct neigh_hash_table *nht;
@@ -1005,8 +1000,7 @@  static void neigh_periodic_work(struct work_struct *work)
 	for (i = 0 ; i < (1 << nht->hash_shift); i++) {
 		np = &nht->hash_buckets[i];
 
-		while ((n = rcu_dereference_protected(*np,
-				lockdep_is_held(&tbl->lock))) != NULL) {
+		neigh_for_each_safe(n, tmp, &nht->hash_heads[i]) {
 			unsigned int state;
 
 			write_lock(&n->lock);
@@ -2756,9 +2750,8 @@  static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
 	for (h = s_h; h < (1 << nht->hash_shift); h++) {
 		if (h > s_h)
 			s_idx = 0;
-		for (n = rcu_dereference(nht->hash_buckets[h]), idx = 0;
-		     n != NULL;
-		     n = rcu_dereference(n->next)) {
+		idx = 0;
+		neigh_for_each(n, &nht->hash_heads[h]) {
 			if (idx < s_idx || !net_eq(dev_net(n->dev), net))
 				goto next;
 			if (neigh_ifindex_filtered(n->dev, filter->dev_idx) ||
@@ -3124,11 +3117,11 @@  void __neigh_for_each_release(struct neigh_table *tbl,
 					lockdep_is_held(&tbl->lock));
 	for (chain = 0; chain < (1 << nht->hash_shift); chain++) {
 		struct neighbour *n;
+		struct hlist_node *tmp;
 		struct neighbour __rcu **np;
 
 		np = &nht->hash_buckets[chain];
-		while ((n = rcu_dereference_protected(*np,
-					lockdep_is_held(&tbl->lock))) != NULL) {
+		neigh_for_each_safe(n, tmp, &nht->hash_heads[chain]) {
 			int release;
 
 			write_lock(&n->lock);