From: Jakub Kicinski <kuba@kernel.org>
To: Oliver Neukum <oneukum@suse.com>
Cc: davem@davemloft.net, edumazet@google.com, pabeni@redhat.com,
netdev@vger.kernel.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCHv2 net] usbnet: fix cyclical race on disconnect with work queue
Date: Thu, 12 Sep 2024 16:59:19 -0700 [thread overview]
Message-ID: <20240912165919.22ad693c@kernel.org> (raw)
In-Reply-To: <bb1cbc3d-fc46-4d0f-90b3-39b25f5bc58e@suse.com>
On Thu, 12 Sep 2024 11:37:14 +0200 Oliver Neukum wrote:
> > barriers? They make it seem like we're doing something clever
> > with memory ordering, while really we're just depending on normal
> > properties of the tasklet/timer/work APIs.
>
> Good question. I added this because they are used in usbnet_defer_kevent()
> which can be used in hard irq context. Are you saying I should check
> whether this is actually needed?
I am slightly bolder, I'm saying that my reading of the code is
that it is in fact not needed :)
We build our "proof of correctness" on tasklet/timer/work APIs
which already provide all necessary barriers.
> > FTR disable_work_sync() would work nicely here but it'd be
> > a PITA for backports.
>
> So should I use it?
Up to you. It'd avoid work rescheduling but the backport would
be a pain, and off top of my head timer doesn't have a disable
so we'd still need the flag.
prev parent reply other threads:[~2024-09-12 23:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-05 13:46 [PATCHv2 net] usbnet: fix cyclical race on disconnect with work queue Oliver Neukum
2024-09-10 9:58 ` Paolo Abeni
2024-09-12 9:30 ` Oliver Neukum
2024-09-10 22:44 ` Jakub Kicinski
2024-09-12 9:37 ` Oliver Neukum
2024-09-12 23:59 ` Jakub Kicinski [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240912165919.22ad693c@kernel.org \
--to=kuba@kernel.org \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=oneukum@suse.com \
--cc=pabeni@redhat.com \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.