Re: [PATCH 3/3] xhci: Don't create stream debugfs files with spinlock held.

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Mike Galbraith <efault@gmx.de>,
	gregkh@linuxfoundation.org, linux-usb@vger.kernel.org,
	Hans de Goede <hdegoede@redhat.com>, Li Jun <jun.li@nxp.com>
Subject: Re: [PATCH 3/3] xhci: Don't create stream debugfs files with spinlock held.
Date: Thu, 29 Oct 2020 16:10:13 +0100	[thread overview]
Message-ID: <20201029151013.zbj6npc736x3o7ux@linutronix.de> (raw)
In-Reply-To: <29cf8ca3-0fe7-da51-c8ae-ad5c67af4dde@linux.intel.com>

On 2020-10-29 15:08:06 [+0200], Mathias Nyman wrote:
> Sebastian, I think you might be missing the first mail in this thread. 

thank you for clearing that up.

> https://lore.kernel.org/linux-usb/20201028203124.375344-4-mathias.nyman@linux.intel.com/
> 
> Let me do a quick recap to avoid confusion here. So far we have 2 issues.
> 
> 1. Lockdep issue #1, stream debugfs entry created with local interrupts disabled and xhci->lock held
>    Cause: 673d74683627b ("usb: xhci: add debugfs support for ep with stream") in v5.10-rc1
>    Fix:  [PATCH 3/3] xhci: Don't create stream debugfs files with spinlock held. (i.e. the mail we are replying to)
>    Comment: easily reproduced, enable lockdep and uas, mount debugfs and connect a UAS device.
>             discovered by both Hans and Mike
> .
> 2. Lockdep issue #2, adding entries to radix tree during (stream) ring expansion with interrupts disabled and xhci->lock held.
>    Cause: unknown, probably a patch since we started using radix trees for finding streams
>    Fix: unknown.
>    Comment: Discovered by Mike when testing fix for issue#1. I suspect it can be reproduced on 5.9 but is 
>    probably really hard as it involves ring expansion.
> 
> -Mathias

Sebastian