Re: [PATCH v2] net: thunderx: rework mac addresses list to u64 array

["Gustavo A. R. Silva" <gustavo@embeddedor.com>]

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.

BTW nice patch. :)

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++;
>>>    				}
>>>    			}
>>>