linux-kernel - Re: [PATCH] IB/core: replace memcpy with ether_addr

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Message-ID: <1503596476.12569.6.camel@perches.com>
Date:   Thu, 24 Aug 2017 10:41:16 -0700
From:   Joe Perches <joe@...ches.com>
To:     Himanshu Jha <himanshujha199640@...il.com>
Cc:     dledford@...hat.com, sean.hefty@...el.com,
        hal.rosenstock@...il.com, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] IB/core: replace memcpy with ether_addr_copy

On Thu, 2017-08-24 at 23:01 +0530, Himanshu Jha wrote:
> On Thu, Aug 24, 2017 at 09:06:32AM -0700, Joe Perches wrote:
> > On Thu, 2017-08-24 at 21:11 +0530, Himanshu Jha wrote:
> > > Use ether_addr_copy to copy an ethernet address of size ETH_ALEN
> > > instead of memcpy.
> > 
> > []
> > diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c
> > []
> > > @@ -798,7 +798,7 @@ int rdma_addr_find_l2_eth_by_grh(const union ib_gid *sgid,
> > >  	if (ret)
> > >  		return ret;
> > >  
> > > -	memcpy(dmac, dev_addr.dst_dev_addr, ETH_ALEN);
> > > +	ether_addr_copy(dmac, dev_addr.dst_dev_addr);
> > >  	dev = dev_get_by_index(&init_net, dev_addr.bound_dev_if);
> > >  	if (!dev)
> > >  		return -ENODEV;
> > > @@ -831,7 +831,7 @@ int rdma_addr_find_smac_by_sgid(union ib_gid *sgid, u8 *smac, u16 *vlan_id)
> > >  	if (ret)
> > >  		return ret;
> > >  
> > > -	memcpy(smac, dev_addr.src_dev_addr, ETH_ALEN);
> > > +	ether_addr_copy(smac, dev_addr.src_dev_addr);
> > >  	return ret;
> > >  }
> > >  EXPORT_SYMBOL(rdma_addr_find_smac_by_sgid);
> > 
> > Both dmac and smac are function arguments.
> > What guarantees these to be
> > aligned properly?
> > 
> 
> Yes, you are correct!
> The arguments should be a pointer to a six byte Ethernet address.

Just for completeness:

The argument should be a pointer to a 6 byte Ethernet address
which is also aligned to an even hardware address.

i.e.: u8 mac_addr[ETH_ALEN] __aligned(2);