Re: [PATCH] net: dsa: properly disconnect the slave PHYs

From: John Crispin
Date: Tue Oct 18 2016 - 08:55:08 EST




On 18/10/2016 14:29, Andrew Lunn wrote:
> On Tue, Oct 18, 2016 at 02:12:40PM +0200, John Crispin wrote:
>> The shutdown code only stopped the PHYs but does not diconnect them
>> properly. This could lead to null pointer deref related kernel oopses
>> during reboot. Fix this by calling phy_disconnect() after the PHYs are
>> stopped.
>
> Humm, i don't follow this.
>
> The phy is disconnected in dsa_slave_destroy(). Why is that not
> sufficient?
>
> Also, after calling dsa_slave_close(), dsa_slave_open() can be
> called. But with your change, the phy has gone, so we are going to
> have trouble.
>
> Andrew
>

Hi Andrew

i am testing on v4.4 which did not have a phy_disconnect() call. this
seems to have been fixed by cda5c15b so please ignore this patch

John

>>
>> Signed-off-by: John Crispin <john@xxxxxxxxxxx>
>> ---
>> net/dsa/slave.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/dsa/slave.c b/net/dsa/slave.c
>> index 68714a5..725d9f7 100644
>> --- a/net/dsa/slave.c
>> +++ b/net/dsa/slave.c
>> @@ -154,8 +154,10 @@ static int dsa_slave_close(struct net_device *dev)
>> struct net_device *master = p->parent->dst->master_netdev;
>> struct dsa_switch *ds = p->parent;
>>
>> - if (p->phy)
>> + if (p->phy) {
>> phy_stop(p->phy);
>> + phy_disconnect(p->phy);
>> + }
>>
>> dev_mc_unsync(master, dev);
>> dev_uc_unsync(master, dev);
>> --
>> 1.7.10.4
>>