netdev - Re: [PATCH net-next 06/12] net: sched: flower: handle concurrent mask insertion

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Date:   Fri, 15 Feb 2019 23:46:23 +0100
From:   Stefano Brivio <sbrivio@...hat.com>
To:     Vlad Buslov <vladbu@...lanox.com>
Cc:     netdev@...r.kernel.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jiri@...nulli.us, davem@...emloft.net
Subject: Re: [PATCH net-next 06/12] net: sched: flower: handle concurrent
 mask insertion

On Thu, 14 Feb 2019 09:47:06 +0200
Vlad Buslov <vladbu@...lanox.com> wrote:

> @@ -1327,19 +1330,36 @@ static int fl_check_assign_mask(struct cls_fl_head *head,
>  	int ret = 0;
>  
>  	rcu_read_lock();
> -	fnew->mask = rhashtable_lookup_fast(&head->ht, mask, mask_ht_params);
> +
> +	/* Insert mask as temporary node to prevent concurrent creation of mask
> +	 * with same key. Any concurrent lookups with same key will return
> +	 * EAGAIN because mask's refcnt is zero. It is safe to insert

Nit: -EAGAIN

-- 
Stefano