linux-kernel - Re: [PATCH v5 1/2] uio_hv_generic: Fix sysfs creation path for ring buffer

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Message-ID: <54905359-035b-4974-bdae-3e60e903adbd@linux.microsoft.com>
Date: Tue, 22 Apr 2025 19:55:45 +0530
From: Naman Jain <namjain@...ux.microsoft.com>
To: Dexuan Cui <decui@...rosoft.com>, KY Srinivasan <kys@...rosoft.com>,
 Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Stephen Hemminger <stephen@...workplumber.org>
Cc: "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "stable@...nel.org" <stable@...nel.org>,
 Saurabh Sengar <ssengar@...ux.microsoft.com>,
 Michael Kelley <mhklinux@...look.com>
Subject: Re: [PATCH v5 1/2] uio_hv_generic: Fix sysfs creation path for ring
 buffer



On 4/18/2025 6:39 AM, Dexuan Cui wrote:
>> From: Naman Jain <namjain@...ux.microsoft.com>
>> Sent: Tuesday, April 15, 2025 9:45 AM
>> Subject: [PATCH v5 1/2] uio_hv_generic: Fix sysfs creation path for ring buffer
>>
>> On regular bootup, devices get registered to VMBus first, so when
>> uio_hv_generic driver for a particular device type is probed,
>> the device is already initialized and added, so sysfs creation in
>> uio_hv_generic probe works fine. However, when device is removed
> 
> Sorry, I'd like to nitpick :-) I guess the maintainer(s) can fix these for you
> so v6 might not be necessary, if there is no comment from others.
> 
> s/uio_hv_generic probe/hv_uio_probe()/
> s/device/the device/
> 
>> and brought back, the channel rescinds and device again gets
> s/rescinds and device/gets rescinded and the device/
> 
>> registered to VMBus. However this time, the uio_hv_generic driver is
>> already registered to probe for that device and in this case sysfs
>> creation is tried before the device's kobject gets initialized
>> completely.
>>
>> Fix this by moving the core logic of sysfs creation for ring buffer,
> s/for/of/
> 
>> from uio_hv_generic to HyperV's VMBus driver, where rest of the sysfs
> s/rest/the rest/
> 
>> attributes for the channels are defined. While doing that, make use
>> of attribute groups and macros, instead of creating sysfs directly,
>> to ensure better error handling and code flow.
>>
>> Problem path:
> s/Problem/Problematic/
> 
>> vmbus_process_offer (new offer comes for the VMBus device)
> s/new/A new/
> 
>>    vmbus_add_channel_work
>>      vmbus_device_register
>>        |-> device_register
>>        |     |...
>>        |     |-> hv_uio_probe
>>        |           |...
>>        |           |-> sysfs_create_bin_file (leads to a warning as
>>        |                 primary channel's kobject, which is used to
> s/primary/the primary/
> 
>>        |                 create sysfs is not yet initialized)
> s/sysfs/the sysfs file, /
> 
>>        |-> kset_create_and_add
>>        |-> vmbus_add_channel_kobj (initialization of primary channel's
> s/primary/the primary/
> 
>>                                    kobject happens later)
>>
> 
> Reviewed-by: Dexuan Cui <decui@...rosoft.com>


Thanks Dexuan. I'll make the required changes and send next patch.

Regards,
Naman