Fwd: [PATCH 0/2] sysfs: allow user-space request for devcoredump

[Arend van Spriel]

+ LKML

---------- Forwarded message ----------
From: Arend van Spriel <aspriel@xxxxxxxxx>
Date: Tue, Jan 9, 2018 at 8:19 PM
Subject: Re: [PATCH 0/2] sysfs: allow user-space request for devcoredump
To: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>


On Tue, Jan 9, 2018 at 7:46 PM, Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, Dec 19, 2017 at 11:03:20AM +0100, Arend van Spriel wrote:
>> From: Arend van Spriel <aspriel@xxxxxxxxx>
>>
>> Since commit 833c95456a70 ("device coredump: add new device coredump class")
>> device drivers have a unified way to provide binary data obtained from a
>> failing_device to user-space. However, there may be use-cases in which the
>> driver has no reason to obtain the data, but user-space wants to initiate
>> it. This adds a coredump device attribute in sysfs when the driver bound to
>> the device supports the newly added coredump driver callback.
>
> What driver is going to set this?  I don't want to add new options to
> the kernel that never get used, do you have a driver to use it?

Hi Greg,

After sending these patches I realized that was going to be your
response, but decided to wait for it. Obviously there is a driver for
which I would like to have an option to create a device coredump from
user-space, ie. the brcm80211 drivers (maintained by my alter-ego ;-)
). I can post these patches again as RFC including the brcm80211
driver patches. Here a bit of background about this itch. A couple of
other driver support their own coredump implementation, ie. not using
dev_coredump class and some support user-space initiated coredump
through debugfs. As that depends on a Kconfig option I looked for
other solutions. At first I considered doing it in dev_coredump class
itself by doing:

# echo 0000:04:00.0 > /sys/class/devcoredump/trigger

with 'trigger' being a new sysfs attribute for devcoredump. However,
using the driver core turned out to be much simpler, but I am still
open for other/better options.

Regards,
Arend