netdev - Re: [PATCH net-next v4 4/6] Convert neighbour iteration to use hlist+macro

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Message-ID: <20241015233851.68607-1-kuniyu@amazon.com>
Date: Tue, 15 Oct 2024 16:38:51 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: <gnaaman@...venets.com>
CC: <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<kuniyu@...zon.com>, <netdev@...r.kernel.org>, <pabeni@...hat.com>
Subject: Re: [PATCH net-next v4 4/6] Convert neighbour iteration to use hlist+macro

From: Gilad Naaman <gnaaman@...venets.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