netdev - Re: [PATCH net-next 2/2] ionic: support sr-iov operations

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Message-ID: <2bdf19d1-55e3-60ff-bf6b-dd4f3097d672@pensando.io>
Date:   Tue, 10 Dec 2019 19:20:38 -0800
From:   Shannon Nelson <snelson@...sando.io>
To:     Parav Pandit <parav@...lanox.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>
Subject: Re: [PATCH net-next 2/2] ionic: support sr-iov operations

On 12/10/19 5:39 PM, Parav Pandit wrote:
> On 12/10/2019 4:54 PM, Shannon Nelson wrote:
>> Add the netdev ops for managing VFs.  Since most of the
>> management work happens in the NIC firmware, the driver becomes
>> mostly a pass-through for the network stack commands that want
>> to control and configure the VFs.
>>
>> We also tweak ionic_station_set() a little to allow for
>> the VFs that start off with a zero'd mac address.
>>
>> Signed-off-by: Shannon Nelson <snelson@...sando.io>
>> ---
[...]
>>   
>> +/* VF commands */
>> +int ionic_set_vf_config(struct ionic *ionic, int vf, u8 attr, u8 *data)
>> +{
> I forgot to mention in my previous review comment that set_vf_config()
> and other VF config friend callback functions can race with
> ionic_sriov_configure().
>
> Former is called from netlink context, later is called from sysfs.
> Its not too hard to crash the system both racing with each other.
>
> Hence protect them using rwsem, where set_vf_() and sriov_configure()
> does down/up_write() and get_vf_config() and get_vf_stat() does
> down_up/read().
>
>

Ah, good catch.  That seems to be relatively a new thing and with a 
quick look around it seems not many drivers deal with that yet. Thanks 
for pointing it out.

sln