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From: Stephen Hemminger <stephen@networkplumber.org>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	davem@davemloft.net, Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v1 3/3] net: WireGuard secure network tunnel
Date: Tue, 31 Jul 2018 13:27:01 -0700	[thread overview]
Message-ID: <20180731132701.522b55e2@xeon-e3> (raw)
In-Reply-To: <20180731191102.2434-4-Jason@zx2c4.com>

On Tue, 31 Jul 2018 21:11:02 +0200
"Jason A. Donenfeld" <Jason@zx2c4.com> wrote:

> +#define push(stack, p, len) ({ \
> +	if (rcu_access_pointer(p)) { \
> +		BUG_ON(len >= 128); \
> +		stack[len++] = rcu_dereference_protected(p, lockdep_is_held(lock)); \
> +	} \
> +	true; \
> +})
> +static void free_root_node(struct allowedips_node __rcu *top, struct mutex *lock)
> +{
> +	struct allowedips_node *stack[128], *node;
> +	unsigned int len;
> +
> +	for (len = 0, push(stack, top, len); len > 0 && (node = stack[--len]) && push(stack, node->bit[0], len) && push(stack, node->bit[1], len);)
> +		call_rcu_bh(&node->rcu, node_free_rcu);
> +}

This looks like you are doing traversal to free a tree.  The stack is there so that you do the rcu callbacks
in the proper order. Won't this create an lot of RCU work at once?

  parent reply	other threads:[~2018-07-31 20:27 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-31 19:10 [PATCH v1 0/3] WireGuard: Secure Network Tunnel Jason A. Donenfeld
2018-07-31 19:11 ` [PATCH v1 1/3] random: Make crng state queryable Jason A. Donenfeld
2018-08-02 21:35   ` Theodore Y. Ts'o
2018-07-31 19:11 ` [PATCH v1 3/3] net: WireGuard secure network tunnel Jason A. Donenfeld
2018-07-31 20:02   ` Andrew Lunn
2018-07-31 20:22   ` Stephen Hemminger
2018-07-31 20:27   ` Stephen Hemminger [this message]
2018-08-03  0:35     ` Jason A. Donenfeld
2018-08-03 14:39       ` Andrew Lunn
2018-08-01  1:21   ` Shawn Landden
2018-08-13 15:40 ` [PATCH v1 0/3] WireGuard: Secure Network Tunnel James Bottomley
2018-08-13 15:53   ` Willy Tarreau
2018-08-13 17:02   ` Jason A. Donenfeld
2018-08-13 17:37     ` James Bottomley
2018-08-13 17:55       ` Jason A. Donenfeld
2018-08-13 18:04         ` James Bottomley

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