On 7/27/22 05:23, Haris Iqbal wrote:
> On Tue, Jul 26, 2022 at 9:56 PM Bob Pearson <rpearsonhpe@xxxxxxxxx> wrote:
>>
>> Currently rxe_init_packet() recomputes ndev from the address
>> vector but struct rxe_dev already holds a reference to ndev.
>>
>> Cleanup rxe_init_packet to use the value of ndev in rxe and drop
>> an unneeded parameter paylen since it is already carried in the
>> packet info struct.
>>
>> Signed-off-by: Bob Pearson <rpearsonhpe@xxxxxxxxx>
>> ---
>> drivers/infiniband/sw/rxe/rxe_loc.h | 2 +-
>> drivers/infiniband/sw/rxe/rxe_net.c | 49 +++++++++++-----------------
>> drivers/infiniband/sw/rxe/rxe_req.c | 2 +-
>> drivers/infiniband/sw/rxe/rxe_resp.c | 3 +-
>> 4 files changed, 23 insertions(+), 33 deletions(-)
>>
>> diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
>> index f9af30f582c6..7f98d296bc0d 100644
>> --- a/drivers/infiniband/sw/rxe/rxe_loc.h
>> +++ b/drivers/infiniband/sw/rxe/rxe_loc.h
>> @@ -93,7 +93,7 @@ void rxe_mw_cleanup(struct rxe_pool_elem *elem);
>>
>> /* rxe_net.c */
>> struct sk_buff *rxe_init_packet(struct rxe_dev *rxe, struct rxe_av *av,
>> - int paylen, struct rxe_pkt_info *pkt);
>> + struct rxe_pkt_info *pkt);
>> int rxe_prepare(struct rxe_av *av, struct rxe_pkt_info *pkt,
>> struct sk_buff *skb);
>> int rxe_xmit_packet(struct rxe_qp *qp, struct rxe_pkt_info *pkt,
>> diff --git a/drivers/infiniband/sw/rxe/rxe_net.c b/drivers/infiniband/sw/rxe/rxe_net.c
>> index c53f4529f098..4a091f236dde 100644
>> --- a/drivers/infiniband/sw/rxe/rxe_net.c
>> +++ b/drivers/infiniband/sw/rxe/rxe_net.c
>> @@ -443,18 +443,22 @@ int rxe_xmit_packet(struct rxe_qp *qp, struct rxe_pkt_info *pkt,
>> return err;
>> }
>>
>> +/**
>> + * rxe_init_packet - allocate and initialize a new skb
>> + * @rxe: rxe device
>> + * @av: remote address vector
>> + * @pkt: packet info
>> + *
>> + * Returns: an skb on success else NULL
>> + */
>> struct sk_buff *rxe_init_packet(struct rxe_dev *rxe, struct rxe_av *av,
>> - int paylen, struct rxe_pkt_info *pkt)
>> + struct rxe_pkt_info *pkt)
>> {
>> unsigned int hdr_len;
>> struct sk_buff *skb = NULL;
>> - struct net_device *ndev;
>> - const struct ib_gid_attr *attr;
>> + struct net_device *ndev = rxe->ndev;
>> const int port_num = 1;
>> -
>> - attr = rdma_get_gid_attr(&rxe->ib_dev, port_num, av->grh.sgid_index);
>> - if (IS_ERR(attr))
>> - return NULL;
>> + int skb_size;
>>
>> if (av->network_type == RXE_NETWORK_TYPE_IPV4)
>> hdr_len = ETH_HLEN + sizeof(struct udphdr) +
>> @@ -463,26 +467,13 @@ struct sk_buff *rxe_init_packet(struct rxe_dev *rxe, struct rxe_av *av,
>> hdr_len = ETH_HLEN + sizeof(struct udphdr) +
>> sizeof(struct ipv6hdr);
>>
>> - rcu_read_lock();
>
> Was removing this rcu lock intentional? If so, do we need a mention of
> this in the commit message why its not needed anymore?
>
The rcu lock was required to use the rdma_read_gid_attr_ndev_rcu() API.
For the rxe driver there is no way that the ndev is changing once the rxe device
is set up and ndev was passed in to rxe_newlink() and saved in the rxe_dev struct.
Not any good reason to do all this work to get ndev when we already know it.
>> - ndev = rdma_read_gid_attr_ndev_rcu(attr);
>> - if (IS_ERR(ndev)) {
>> - rcu_read_unlock();
>> - goto out;
>> - }
>> - skb = alloc_skb(paylen + hdr_len + LL_RESERVED_SPACE(ndev),
>> - GFP_ATOMIC);
>> -
>> - if (unlikely(!skb)) {
>> - rcu_read_unlock();
>> - goto out;
>> - }
>> -
>> - skb_reserve(skb, hdr_len + LL_RESERVED_SPACE(ndev));
>> -
>> - /* FIXME: hold reference to this netdev until life of this skb. */
>> - skb->dev = ndev;
>> - rcu_read_unlock();
>> + skb_size = LL_RESERVED_SPACE(ndev) + hdr_len + pkt->paylen;
>> + skb = alloc_skb(skb_size, GFP_ATOMIC);
>> + if (unlikely(!skb))
>> + return NULL;
>>
>> + skb_reserve(skb, LL_RESERVED_SPACE(ndev) + hdr_len);
>> + skb->dev = ndev;
>> if (av->network_type == RXE_NETWORK_TYPE_IPV4)
>> skb->protocol = htons(ETH_P_IP);
>> else
>> @@ -490,11 +481,9 @@ struct sk_buff *rxe_init_packet(struct rxe_dev *rxe, struct rxe_av *av,
>>
>> pkt->rxe = rxe;
>> pkt->port_num = port_num;
>> - pkt->hdr = skb_put(skb, paylen);
>> - pkt->mask |= RXE_GRH_MASK;
>> + pkt->hdr = skb_put(skb, pkt->paylen);
>> + pkt->mask |= RXE_GRH_MASK;
>>
>> -out:
>> - rdma_put_gid_attr(attr);
>> return skb;
>> }
>>
>> diff --git a/drivers/infiniband/sw/rxe/rxe_req.c b/drivers/infiniband/sw/rxe/rxe_req.c
>> index 49e8f54db6f5..e72db960d7ea 100644
>> --- a/drivers/infiniband/sw/rxe/rxe_req.c
>> +++ b/drivers/infiniband/sw/rxe/rxe_req.c
>> @@ -397,7 +397,7 @@ static struct sk_buff *init_req_packet(struct rxe_qp *qp,
>> pkt->paylen = paylen;
>>
>> /* init skb */
>> - skb = rxe_init_packet(rxe, av, paylen, pkt);
>> + skb = rxe_init_packet(rxe, av, pkt);
>> if (unlikely(!skb))
>> return NULL;
>>
>> diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
>> index b36ec5c4d5e0..02a5d4ebb45e 100644
>> --- a/drivers/infiniband/sw/rxe/rxe_resp.c
>> +++ b/drivers/infiniband/sw/rxe/rxe_resp.c
>> @@ -670,8 +670,9 @@ static struct sk_buff *prepare_ack_packet(struct rxe_qp *qp,
>> */
>> pad = (-payload) & 0x3;
>> paylen = rxe_opcode[opcode].length + payload + pad + RXE_ICRC_SIZE;
>> + ack->paylen = paylen;
>
> Maybe remove the old ack->paylen assignment which is done later in
> this function?
>
Agreed. Will send a v2 with this change.
>>
>> - skb = rxe_init_packet(rxe, &qp->pri_av, paylen, ack);
>> + skb = rxe_init_packet(rxe, &qp->pri_av, ack);
>> if (!skb)
>> return NULL;
>>
>> --
>> 2.34.1
>>
Bob
