netdev - Re: [PATCH RFC 5/6] net: Generic resolver backend

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Date:   Wed, 14 Sep 2016 11:49:11 +0200
From:   Thomas Graf <tgraf@...g.ch>
To:     Tom Herbert <tom@...bertland.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH RFC 5/6] net: Generic resolver backend

On 09/09/16 at 04:19pm, Tom Herbert wrote:
> diff --git a/net/core/resolver.c b/net/core/resolver.c
> new file mode 100644
> index 0000000..61b36c5
> --- /dev/null
> +++ b/net/core/resolver.c
> @@ -0,0 +1,267 @@
> +#include <linux/errno.h>
> +#include <linux/ip.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/netlink.h>
> +#include <linux/skbuff.h>
> +#include <linux/socket.h>
> +#include <linux/types.h>
> +#include <linux/vmalloc.h>
> +#include <net/checksum.h>
> +#include <net/ip.h>
> +#include <net/ip6_fib.h>
> +#include <net/lwtunnel.h>
> +#include <net/protocol.h>
> +#include <net/resolver.h>
> +#include <uapi/linux/ila.h>

This include list could be stripped down a bit. ila, lwt, fib, ...

> +
> +static struct net_rslv_ent *net_rslv_new_ent(struct net_rslv *nrslv,
> +					     void *key)

Comment above that net_rslv_get_lock() must be held?

> +{
> +	struct net_rslv_ent *nrent;
> +	int err;
> +
> +	nrent = kzalloc(sizeof(*nrent) + nrslv->obj_size, GFP_KERNEL);

GFP_ATOMIC since you typically hold net_rslv_get_lock() spinlock?

> +	if (!nrent)
> +		return ERR_PTR(-EAGAIN);
> +
> +	/* Key is always at beginning of object data */
> +	memcpy(nrent->object, key, nrslv->params.key_len);
> +
> +	/* Initialize user data */
> +	if (nrslv->rslv_init)
> +		nrslv->rslv_init(nrslv, nrent);
> +
> +	/* Put in hash table */
> +	err = rhashtable_lookup_insert_fast(&nrslv->rhash_table,
> +					    &nrent->node, nrslv->params);
> +	if (err)
> +		return ERR_PTR(err);
> +
> +	if (nrslv->timeout) {
> +		/* Schedule timeout for resolver */
> +		INIT_DELAYED_WORK(&nrent->timeout_work, net_rslv_delayed_work);

Should this be done before inserting into rhashtable?

> +		schedule_delayed_work(&nrent->timeout_work, nrslv->timeout);
> +	}
> +
> +	nrent->nrslv = nrslv;

Same here.  net_rslv_cancel_all_delayed_work() walking the rhashtable could
see ->nrslv as NULL.