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Date:   Fri, 6 Apr 2018 04:53:59 -0700
From:   Vadim Lomovtsev <Vadim.Lomovtsev@caviumnetworks.com>
To:     "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc:     sgoutham@cavium.com, sunil.kovvuri@gmail.com, rric@kernel.org,
        linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, davem@davemloft.net,
        dnelson@redhat.com, Vadim Lomovtsev <Vadim.Lomovtsev@cavium.com>
Subject: Re: [PATCH v2] net: thunderx: rework mac addresses list to u64 array
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On Fri, Apr 06, 2018 at 06:47:26AM -0500, Gustavo A. R. Silva wrote:
> 
> 
> On 04/06/2018 06:43 AM, Vadim Lomovtsev wrote:
> > Hi Gustavo,
> > 
> > On Fri, Apr 06, 2018 at 06:36:28AM -0500, Gustavo A. R. Silva wrote:
> > > Hi Vadim,
> > > 
> > > On 04/06/2018 06:14 AM, 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")
> > > 
> > > It'd be nice if you add:
> > > 
> > > Reported-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> > 
> > Ok, I could do that.
> > 
> > Just to explain .. I didn't do it yet since I get such report from
> > Dan Carpenter intially (https://www.spinics.net/lists/linux-kernel-janitors/msg40720.html)
> > and was working on it when found you patches, so then asking you to give
> > me some time to prepare and test update to driver.
> > 
> 
> Oh I got it. Not big deal. I think in this case you should add Dan's
> Reported-by instead.

Ok then.

> 
> BTW nice patch. :)
>

Thank you for reviewing it.

WBR,
Vadim

> Thanks
> --
> Gustavo
> 
> > So would it be acceptable put two tags 'Reported-by:' then ?
> > 
> > WBR,
> > Vadim
> > 
> > > 
> > > Thanks
> > > --
> > > Gustavo
> > > 
> > > > Signed-off-by: Vadim Lomovtsev <Vadim.Lomovtsev@cavium.com>
> > > > ---
> > > > Changes from v1 to v2:
> > > >    - C99 syntax: update xcast_addr_list struct field mc[0] -> mc[];
> > > > 
> > > > ---
> > > >    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..448d1fafc827 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[];
> > > >    };
> > > >    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++;
> > > >    				}
> > > >    			}
> > > >