linux-kernel - Re: [PATCH 06/11] net/bonding: take msecs_to_jiffies

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Message-ID: <20130510135810.GA30139@unicorn.suse.cz>
Date:	Fri, 10 May 2013 15:58:10 +0200
From:	Michal Kubecek <mkubecek@...e.cz>
To:	Imre Deak <imre.deak@...el.com>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Jay Vosburgh <fubar@...ibm.com>,
	Andy Gospodarek <andy@...yhouse.net>, netdev@...r.kernel.org
Subject: Re: [PATCH 06/11] net/bonding: take msecs_to_jiffies_min into use

On Fri, May 10, 2013 at 03:13:24PM +0300, Imre Deak wrote:
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -1751,7 +1751,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>  	read_lock(&bond->lock);
>  
>  	new_slave->last_arp_rx = jiffies -
> -		(msecs_to_jiffies(bond->params.arp_interval) + 1);
> +		(msecs_to_jiffies_min(bond->params.arp_interval));
>  
>  	if (bond->params.miimon && !bond->params.use_carrier) {
>  		link_reporting = bond_check_dev_link(bond, slave_dev, 1);

This "+ 1" was actually meant as "plus one". We need to ensure that

  slave->last_arp_rx + msecs_to_jiffies(bond->params.arp_interval)

is strictly less than current value of jiffies. So with proposed
definition of msecs_to_jiffies_min() it works correctly but if the
implementation ever changes in such way that

  msecs_to_jiffies_min(x) >= msecs_to_jiffies(x)

for some value of x, the code would be incorrect.

                                                       Michal Kubeček

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