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

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Message-ID:
 <BL4PR21MB4627D99C78C22A8C3355059CBFBF2@BL4PR21MB4627.namprd21.prod.outlook.com>
Date: Fri, 18 Apr 2025 01:09:11 +0000
From: Dexuan Cui <decui@...rosoft.com>
To: Naman Jain <namjain@...ux.microsoft.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

> 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s/rescinds and device/gets rescinded and the device/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>