linux-kernel - Re: [PATCH] devcoredump: Send uevent once devcd is ready

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Message-ID: <57d38bd4-d9ea-6ce4-b7c1-1a05097c7338@quicinc.com>
Date:   Tue, 7 Nov 2023 16:31:42 +0530
From:   Mukesh Ojha <quic_mojha@...cinc.com>
To:     Johannes Berg <johannes@...solutions.net>,
        Greg KH <gregkh@...uxfoundation.org>
CC:     <rafael@...nel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] devcoredump: Send uevent once devcd is ready



On 11/7/2023 1:07 AM, Johannes Berg wrote:
> On Mon, 2023-11-06 at 20:36 +0100, Greg KH wrote:
>> On Mon, Nov 06, 2023 at 07:55:35PM +0530, Mukesh Ojha wrote:
>>> dev_coredumpm() creates a devcoredump device and adds it
>>> to the core kernel framework which eventually end up
>>> sending uevent to the user space and later creates a
>>> symbolic link to the failed device. An application
>>> running in userspace may be interested in this symbolic
>>> link to get the name of the failed device.
>>>
>>> In a issue scenario, once uevent sent to the user space
>>> it start reading '/sys/class/devcoredump/devcdX/failing_device'
>>> to get the actual name of the device which might not been
>>> created and it is in its path of creation.
>>>
>>> To fix this, suppress sending uevent till the failing device
>>> symbolic link gets created and send uevent once symbolic
>>> link is created successfully.
>>>
>>> Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
>>
>> What commit id does this fix?
>>
> 
> I guess the original introduction.
> 
>>   What in-kernel driver does this affect
>> that is using devcoredump?
>>
> 
> All of them really, it's really about how fast userspace is to access it
> after the event.
> 
> Looks fine to me, FWIW, but a Fixes tag wouldn't hurt.

Thanks, will add the Fixes tag.

-Mukesh
> 
> johannes