netdev - Re: [patch net-next 0/4] net: devlink: sync flash and dev info command

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Date:   Fri, 26 Aug 2022 14:24:52 +0530
From:   "Kumar, M Chetan" <m.chetan.kumar@...ux.intel.com>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        davem@...emloft.net, idosch@...dia.com, pabeni@...hat.com,
        edumazet@...gle.com, saeedm@...dia.com, jacob.e.keller@...el.com,
        vikas.gupta@...adcom.com, gospo@...adcom.com,
        chandrashekar.devegowda@...el.com, soumya.prakash.mishra@...el.com,
        linuxwwan@...el.com, hua.yang@...iatek.com
Subject: Re: [patch net-next 0/4] net: devlink: sync flash and dev info
 command

Looped hua.yang@...iatek.com to email.

On 8/24/2022 2:17 PM, Jiri Pirko wrote:
> Tue, Aug 23, 2022 at 06:29:48PM CEST, m.chetan.kumar@...ux.intel.com wrote:
>> On 8/23/2022 5:50 PM, Jiri Pirko wrote:
>>> Tue, Aug 23, 2022 at 12:09:06PM CEST, m.chetan.kumar@...ux.intel.com wrote:
>>>> On 8/19/2022 1:55 PM, Jiri Pirko wrote:
>>>>> Fri, Aug 19, 2022 at 04:49:40AM CEST, kuba@...nel.org wrote:
>>>>>> On Thu, 18 Aug 2022 15:00:38 +0200 Jiri Pirko wrote:
>>>>>>> Currently it is up to the driver what versions to expose and what flash
>>>>>>> update component names to accept. This is inconsistent. Thankfully, only
>>>>>>> netdevsim is currently using components, so it is a good time
>>>>>>> to sanitize this.
>>>>>>
>>>>>> Please take a look at recently merged code - 5417197dd516 ("Merge branch
>>>>>> 'wwan-t7xx-fw-flashing-and-coredump-support'"), I don't see any versions
>>>>>> there so I think you're gonna break them?
>>>>>
>>>>> Ah, crap. Too late :/ They are passing the string to FW (cmd is
>>>>> the component name here):
>>>>> static int t7xx_devlink_fb_flash(const char *cmd, struct t7xx_port *port)
>>>>> {
>>>>>            char flash_command[T7XX_FB_COMMAND_SIZE];
>>>>>
>>>>>            snprintf(flash_command, sizeof(flash_command), "%s:%s", T7XX_FB_CMD_FLASH, cmd);
>>>>>            return t7xx_devlink_fb_raw_command(flash_command, port, NULL);
>>>>> }
>>>>>
>>>>> This breaks the pairing with info.versions assumption. Any possibility
>>>>> to revert this and let them redo?
>>>>>
>>>>> Ccing m.chetan.kumar@...ux.intel.com, chandrashekar.devegowda@...el.com,
>>>>> soumya.prakash.mishra@...el.com
>>>>>
>>>>> Guys, could you expose one version for component you are flashing? We
>>>>> need 1:1 mapping here.
>>>>
>>>> Thanks for the heads-up.
>>>> I had a look at the patch & my understanding is driver is supposed
>>>> to expose flash update component name & version details via
>>>> devlink_info_version_running_put_ext().
>>>
>>> Yes.
>>>
>>>>
>>>> Is version value a must ? Internally version value is not used for making any
>>>> decision so in case driver/device doesn't support it should be ok to pass
>>>> empty string ?
>>>
>>> No.
>>>
>>>>
>>>> Ex:
>>>> devlink_info_version_running_put_ext(req, "fw", "",
>>>> DEVLINK_INFO_VERSION_TYPE_COMPONENT);
>>>>
>>>> One observation:-
>>>> While testing I noticed "flash_components:" is not getting displayed as
>>>> mentioned in cover note.
>>>
>>> You need iproute2 patch for that which is still in my queue:
>>> https://github.com/jpirko/iproute2_mlxsw/commit/e1d36409362257cc42a435f6695d2058ab7ab683
>>
>> Thanks. After applying this patch "flash_components" details are getting
>> displayed.
>>
>> Another observation is if NULL is passed for version_value there is a crash.
> 
> So don't pass NULL :)
> 
> 
>> Below is the backtrace.
>>
>> 3187.556637] BUG: kernel NULL pointer dereference, address: 0000000000000000
>> [ 3187.556659] #PF: supervisor read access in kernel mode
>> [ 3187.556666] #PF: error_code(0x0000) - not-present page
>> 3187.556791] Call Trace:
>> [ 3187.556796]  <TASK>
>> [ 3187.556801]  ? devlink_info_version_put+0x112/0x1d0
>> [ 3187.556823]  ? __nla_put+0x20/0x30
>> [ 3187.556833]  devlink_info_version_running_put_ext+0x1c/0x30
>> [ 3187.556851]  t7xx_devlink_info_get+0x37/0x40 [mtk_t7xx]
>> [ 3187.556880]  devlink_nl_info_fill.constprop.0+0xa1/0x120
>> [ 3187.556892]  devlink_nl_cmd_info_get_dumpit+0xa8/0x140
>> [ 3187.556901]  netlink_dump+0x1a3/0x340
>> [ 3187.556913]  __netlink_dump_start+0x1d0/0x290
>>
>> Is driver expected to set version number along with component name ?
> 
> Of course.
> 
> 
>>
>> mtk_t7xx WWAN driver is using the devlink interface for flashing the fw to
>> WWAN device. If WWAN device is not capable of supporting the versioning for
>> each component how should we handle ? Please suggest.
> 
> The user should have a visibility about what version is currently
> stored/running in the device. You should expose it.

If the only intention of this component version is to give a visbility 
to user, the WWAN Driver exposes the AT & MBIM control ports. 
Applications like Modem Manager uses AT/MBIM commands to obtain fw 
version info.

So would it be ok to keep component version as an optional for WWAN 
drivers ?

-- 
Chetan