linux-kernel - Re: [PATCH 1/2] Revert "drivers: core: synchronize really_probe() and dev

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2025022051-happy-plant-b40b@gregkh>
Date: Thu, 20 Feb 2025 08:13:00 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
	Danilo Krummrich <dakr@...nel.org>, linux-kernel@...r.kernel.org,
	"Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
	Dirk Behme <dirk.behme@...bosch.com>
Subject: Re: [PATCH 1/2] Revert "drivers: core: synchronize really_probe()
 and dev_uevent()"

On Wed, Feb 19, 2025 at 10:46:44PM -0800, Dmitry Torokhov wrote:
> This reverts commit c0a40097f0bc81deafc15f9195d1fb54595cd6d0.
> 
> Probing a device can take arbitrary long time. In the field we observed
> that, for example, probing a bad micro-SD cards in an external USB card
> reader (or maybe cards were good but cables were flaky) sometimes takes
> longer than 2 minutes due to multiple retries at various levels of the
> stack. We can not block uevent_show() method for that long because udev
> is reading that attribute very often and that blocks udev and interferes
> with booting of the system.
> 
> The change that introduced locking was concerned with dev_uevent()
> racing with unbinding the driver. However we can handle it without
> locking (which will be done in subsequent patch).

So shouldn't we take the second patch first to prevent any issues here?

> There was also claim that synchronization with probe() is needed to
> properly load USB drivers, however this is a red herring: the change
> adding the lock was introduced in May of last year and USB loading and
> probing worked properly for many years before that.
> 
> Revert the harmful locking.
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

No Fixes: or cc: stable for this?

thanks,

greg k-h