netdev - Re: [PATCH net v1] ice: do not reserve resources for RDMA when disabled

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Message-ID: <793f72a2-54c3-42b5-84c1-a2ae24b87223@intel.com>
Date: Mon, 25 Nov 2024 09:32:03 +0100
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: "Ertman, David M" <david.m.ertman@...el.com>, Jesse Brandeburg
	<jesse.brandeburg@...ux.dev>, "jbrandeb@...nel.org" <jbrandeb@...nel.org>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>
Subject: Re: [PATCH net v1] ice: do not reserve resources for RDMA when
 disabled

[CC IWL]

On 11/22/24 23:35, Ertman, David M wrote:
>> -----Original Message-----
>> From: Jesse Brandeburg <jesse.brandeburg@...ux.dev>
>> Sent: Thursday, November 21, 2024 5:50 PM
>> To: Ertman, David M <david.m.ertman@...el.com>; jbrandeb@...nel.org;
>> netdev@...r.kernel.org
>> Subject: Re: [PATCH net v1] ice: do not reserve resources for RDMA when
>> disabled
>>
>> On 11/15/24 10:46 AM, Jesse Brandeburg wrote:
>>> On 11/14/24 10:06 AM, Ertman, David M wrote:
>>>>>        case ICE_AQC_CAPS_RDMA:
>>>>> -        caps->rdma = (number == 1);
>>>>> +        if (IS_ENABLED(CONFIG_INFINIBAND_IRDMA))
>>>>> +            caps->rdma = (number == 1);
>>>>>            ice_debug(hw, ICE_DBG_INIT, "%s: rdma = %d\n", prefix,
>>>>
>>>> The HW caps struct should always accurately reflect the capabilities
>>>> of the HW being probed.  Since this
>>>
>>> why must it accurately reflect the capability of the hardware? The
>>> driver state and capability is a reflection of the combination of both,
>>> so I'm not sure what the point of your statement.
>>>
>>>> is a kernel configuration (i.e. software) consideration, the more
>>>> appropriate approach would be to control
>>>> the PF flag "ICE_FLAG_RDMA_ENA" based on the kernel CONFIG setting.
>>>
>>> I started making the changes you suggested, but the ICE_FLAG_RDMA_ENA is
>>> blindly set by the LAG code, if the cap.rdma is enabled. see
>>> ice_set_rdma_cap(). This means the disable won't stick.
>>>
>>> Unless I'm misunderstanding something, ICE_FLAG_RDMA_ENA is used both as
>>> a gate and as a state, which is a design issue. This leaves no choice
>>> but to implement the way I did in this v1 patch. Do you see any other
>>> option to make a simple change that is safe for backporting to stable?
>>
>> Any comments here Dave?
> 
> Jesse,
> 
> Looking at the FLAG as used in the ice driver, it is used as an ephemeral state for
> the enablement of RDMA (gated by the value of the capabilities struct).  So, I agree
> that a kernel-wide config value should not be tied to it as well.
> 
> Since the kernel config value will not change for the life of the driver, it should be
> OK to alter the capabilities struct value based on the kernel's configuration.
> 
> Sorry for the thrash.
> 
> DaveE
> 
> Acked-by: Dave Ertman <david.m.ertman@...el.com>