Re: 6.7.0-rc1 + hacks deadlock bug, wifi netdev delete + cat of debugfs file.

[Johannes Berg <johannes@sipsolutions.net>]

On Tue, 2023-11-07 at 14:08 -0800, Ben Greear wrote:
> Hello,
> 
> I think this lockup is because iw is holding rtnl and wiphy mutex,
> and is blocked waiting for debugfs to be closed.  Another 'cat'
> program has debugfs file open, and is blocking on trying to acquire
> wiphy mutex.
> 
> I think we must not acquire wiphy mutex in debugfs methods, somehow,
> to resolve this deadlock.  I do not know a safe way to do that.

Hmm. I almost want to say "don't do that then", but I guess you're just
randomly accessing debugfs files.

I guess we can at least make the mutex acquisition in debugfs killable
(or interruptible), so you can recover from this.

But fundamentally this is probably not really even a new issue.

I don't know how to interrupt a specific task that's stuck in a specific
debugfs file though, e.g. when removing them.

johannes