netdev - Re: [PATCH net-next v2 5/6] gtp: add socket to pdp context

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Date:   Thu, 2 Feb 2017 15:28:42 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Andreas Schultz <aschultz@...p.net>
Cc:     netdev <netdev@...r.kernel.org>, laforge <laforge@...monks.org>,
        Lionel Gauthier <Lionel.Gauthier@...ecom.fr>,
        openbsc <openbsc@...ts.osmocom.org>
Subject: Re: [PATCH net-next v2 5/6] gtp: add socket to pdp context

On Thu, Feb 02, 2017 at 03:12:55PM +0100, Andreas Schultz wrote:
> Hi,
> 
> ----- On Feb 2, 2017, at 2:56 PM, pablo pablo@...filter.org wrote:
> 
> > On Mon, Jan 30, 2017 at 05:37:12PM +0100, Andreas Schultz wrote:
> >> Having the socket present in context simplifies the sending logic.
> >> It also fixes the invalid assumption that we have to use the same
> >> sending socket for all client IP's on a specific gtp interface.
> >> 
> >> Signed-off-by: Andreas Schultz <aschultz@...p.net>
> >> ---
> >>  drivers/net/gtp.c | 72 ++++++++++++++++++++++++++++++-------------------------
> >>  1 file changed, 39 insertions(+), 33 deletions(-)
> >> 
> >> diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
> >> index 68c6c9b..ff00597 100644
> >> --- a/drivers/net/gtp.c
> >> +++ b/drivers/net/gtp.c
> > [...]
> >> @@ -984,16 +966,26 @@ static int ipv4_pdp_add(struct gtp_dev *gtp, struct
> >> genl_info *info)
> >>  	return 0;
> >>  }
> >>  
> >> +static void pdp_context_free(struct rcu_head *head)
> >> +{
> >> +	struct pdp_ctx *pctx = container_of(head, struct pdp_ctx, rcu_head);
> >> +
> >> +	sock_put(pctx->sk);
> >> +	kfree(pctx);
> >> +}
> >> +
> >>  static void pdp_context_delete(struct pdp_ctx *pctx)
> >>  {
> >>  	hlist_del_rcu(&pctx->hlist_tid);
> >>  	hlist_del_rcu(&pctx->hlist_addr);
> >> -	kfree(pctx);
> >> +	call_rcu(&pctx->rcu_head, pdp_context_free);
> > 
> > This is fixing incorrect rcu conversion in 4/6. Please, fix this there.
> 
> Ehm, right, but the kfree in 4/6 could have been a kfree_rcu instead without
> the call_rcu.
> 
> Do you prefer to introduce the call_rcu in 4/6 and then just add the sock_put
> in this patch or should I change 4/6 to kfree_rcu and do the call_rcu
> conversion here?

I suggest you just call kfree_rcu() from 4/6.

Regarding holding socket reference, see my comment for patch 1/6.