Re: [PATCH] net: thunderx: rework mac addresses list to u64 array

Vadim Lomovtsev
2018-04-05T15:00:19Z

[correct Roberts' address]

On Thu, Apr 05, 2018 at 07:57:56AM -0700, Vadim Lomovtsev wrote:
> From: Vadim Lomovtsev <Vadim.Lomovtsev@cavium.com>
>
> It is too expensive to pass u64 values via linked list, instead
> allocate array for them by overall number of mac addresses from netdev.
>
> This eventually removes multiple kmalloc() calls, aviod memory
> fragmentation and allow to put single null check on kmalloc
> return value in order to prevent a potential null pointer dereference.
>
> Addresses-Coverity-ID: 1467429 ("Dereference null return value")
> Fixes: 37c3347eb247 ("net: thunderx: add ndo_set_rx_mode callback implementation for VF")
> Signed-off-by: Vadim Lomovtsev <Vadim.Lomovtsev@cavium.com>
> ---
> drivers/net/ethernet/cavium/thunder/nic.h | 7 +-----
> drivers/net/ethernet/cavium/thunder/nicvf_main.c | 28 +++++++++---------------
> 2 files changed, 11 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/net/ethernet/cavium/thunder/nic.h b/drivers/net/ethernet/cavium/thunder/nic.h
> index 5fc46c5a4f36..da052159f014 100644
> --- a/drivers/net/ethernet/cavium/thunder/nic.h
> +++ b/drivers/net/ethernet/cavium/thunder/nic.h
> @@ -265,14 +265,9 @@ struct nicvf_drv_stats {
>
> struct cavium_ptp;
>
> -struct xcast_addr {
> - struct list_head list;
> - u64 addr;
> -};
> -
> struct xcast_addr_list {
> - struct list_head list;
> int count;
> + u64 mc[0];
> };
>
> struct nicvf_work {
> diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_main.c b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> index 1e9a31fef729..a26d8bc92e01 100644
> --- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> +++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> @@ -1929,7 +1929,7 @@ static void nicvf_set_rx_mode_task(struct work_struct *work_arg)
> work.work);
> struct nicvf *nic = container_of(vf_work, struct nicvf, rx_mode_work);
> union nic_mbx mbx = {};
> - struct xcast_addr *xaddr, *next;
> + u8 idx = 0;
>
> if (!vf_work)
> return;
> @@ -1956,16 +1956,10 @@ static void nicvf_set_rx_mode_task(struct work_struct *work_arg)
> /* check if we have any specific MACs to be added to PF DMAC filter */
> if (vf_work->mc) {
> /* now go through kernel list of MACs and add them one by one */
> - list_for_each_entry_safe(xaddr, next,
> - &vf_work->mc->list, list) {
> + for (idx = 0; idx < vf_work->mc->count; idx++) {
> mbx.xcast.msg = NIC_MBOX_MSG_ADD_MCAST;
> - mbx.xcast.data.mac = xaddr->addr;
> + mbx.xcast.data.mac = vf_work->mc->mc[idx];
> nicvf_send_msg_to_pf(nic, &mbx);
> -
> - /* after receiving ACK from PF release memory */
> - list_del(&xaddr->list);
> - kfree(xaddr);
> - vf_work->mc->count--;
> }
> kfree(vf_work->mc);
> }
> @@ -1996,17 +1990,15 @@ static void nicvf_set_rx_mode(struct net_device *netdev)
> mode |= BGX_XCAST_MCAST_FILTER;
> /* here we need to copy mc addrs */
> if (netdev_mc_count(netdev)) {
> - struct xcast_addr *xaddr;
> -
> - mc_list = kmalloc(sizeof(*mc_list), GFP_ATOMIC);
> - INIT_LIST_HEAD(&mc_list->list);
> + mc_list = kmalloc(sizeof(*mc_list) +
> + sizeof(u64) * netdev_mc_count(netdev),
> + GFP_ATOMIC);
> + if (unlikely(!mc_list))
> + return;
> + mc_list->count = 0;
> netdev_hw_addr_list_for_each(ha, &netdev->mc) {
> - xaddr = kmalloc(sizeof(*xaddr),
> - GFP_ATOMIC);
> - xaddr->addr =
> + mc_list->mc[mc_list->count] =
> ether_addr_to_u64(ha->addr);
> - list_add_tail(&xaddr->list,
> - &mc_list->list);
> mc_list->count++;
> }
> }
> --
> 2.14.3
>