Re: [PATCH] devcoredump: increase the device delete timeout to 10 mins

[Johannes Berg]

On Tue, 2022-02-08 at 13:40 -0800, Abhinav Kumar wrote:
> > 
> I am checking what usermode sees and will get back ( I didnt see an 
> error do most likely it was EOF ). I didnt follow the second part.

I think probably it got -ENODEV, looking at kernfs_file_read_iter().

> If the file descriptor read returns EOF, even if we consider them 
> separate how will it resolve this issue?
> 
> My earlier questions were related to fixing it in devcoredump to detect
> and fix it there. Are you suggesting to fix in usermode instead? How?
> 

Yeah, no, you cannot fix it in userspace.

But I just followed the rabbit hole down kernfs and all, and it looks
like indeed the read would be cut short with -ENODEV, sorry.

It doesn't look like there's good API for this, but it seems at least
from the underlying kernfs POV it should be possible to get_device() in
open and put_device() in release, so that the device sticks around while
somebody has the file open? It's entirely virtual, so this should be OK?

johannes