netdev - Re: [RFC PATCH 03/14] packet: enable AF

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Message-ID: <CAJ+HfNit=H8h58-jixZuWKpmPj02XhGXojDU_01q6q3mw0Qfww@mail.gmail.com>
Date:   Fri, 3 Nov 2017 11:02:24 +0100
From:   Björn Töpel <bjorn.topel@...il.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     "Karlsson, Magnus" <magnus.karlsson@...el.com>,
        Alexander Duyck <alexander.h.duyck@...el.com>,
        Alexander Duyck <alexander.duyck@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        Alexei Starovoitov <ast@...com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        michael.lundkvist@...csson.com, ravineet.singh@...csson.com,
        Daniel Borkmann <daniel@...earbox.net>,
        Network Development <netdev@...r.kernel.org>,
        Björn Töpel <bjorn.topel@...el.com>,
        jesse.brandeburg@...el.com, anjali.singhai@...el.com,
        rami.rosen@...el.com, jeffrey.b.shaw@...el.com,
        ferruh.yigit@...el.com, qi.z.zhang@...el.com
Subject: Re: [RFC PATCH 03/14] packet: enable AF_PACKET V4 rings

2017-11-03 5:16 GMT+01:00 Willem de Bruijn <willemdebruijn.kernel@...il.com>:
>> +/**
>> + * tp4q_enqueue_from_array - Enqueue entries from packet array to tp4 queue
>> + *
>> + * @a: Pointer to the packet array to enqueue from
>> + * @dcnt: Max number of entries to enqueue
>> + *
>> + * Returns 0 for success or an errno at failure
>> + **/
>> +static inline int tp4q_enqueue_from_array(struct tp4_packet_array *a,
>> +                                         u32 dcnt)
>> +{
>> +       struct tp4_queue *q = a->tp4q;
>> +       unsigned int used_idx = q->used_idx;
>> +       struct tpacket4_desc *d = a->items;
>> +       int i;
>> +
>> +       if (q->num_free < dcnt)
>> +               return -ENOSPC;
>> +
>> +       q->num_free -= dcnt;
>
> perhaps annotate with a lockdep_is_held to document which lock
> ensures mutual exclusion on the ring. Different for tx and rx?
>

Good idea. I'll give that a try!

>> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
>> index b39be424ec0e..190598eb3461 100644
>> --- a/net/packet/af_packet.c
>> +++ b/net/packet/af_packet.c
>> @@ -189,6 +189,9 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
>>  #define BLOCK_O2PRIV(x)        ((x)->offset_to_priv)
>>  #define BLOCK_PRIV(x)          ((void *)((char *)(x) + BLOCK_O2PRIV(x)))
>>
>> +#define RX_RING 0
>> +#define TX_RING 1
>> +
>
> Not needed if using bool for tx_ring below. The test effectively already
> treats it as bool: does not explicitly test these constants.
>
>> +static void packet_clear_ring(struct sock *sk, int tx_ring)
>> +{
>> +       struct packet_sock *po = pkt_sk(sk);
>> +       struct packet_ring_buffer *rb;
>> +       union tpacket_req_u req_u;
>> +
>> +       rb = tx_ring ? &po->tx_ring : &po->rx_ring;
>
>
> I meant here.

Yup, I'll remove/clean this up.


Björn