linux-kernel - Re: Question on 5.4.55 merge into 5.4-rt

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: <20200817134109.hu73gjafbdb2n3rz@linutronix.de>
Date:   Mon, 17 Aug 2020 15:41:09 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        linux-rt-users <linux-rt-users@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Carsten Emde <C.Emde@...dl.org>,
        John Kacur <jkacur@...hat.com>, Daniel Wagner <wagi@...om.org>,
        Tom Zanussi <zanussi@...nel.org>,
        "Srivatsa S. Bhat" <srivatsa@...il.mit.edu>
Subject: Re: Question on 5.4.55 merge into 5.4-rt

On 2020-08-14 18:54:21 [-0400], Steven Rostedt wrote:
> 
> When merging 5.4.55 into 5.4-rt I hit the following conflict:
…
> 
> Where we are doing something slightly different. Placing the skb on the
> sd->tofree_queue and raising NET_RX_SOFTIQ instead.
> 
> Now that the vanilla stable 5.4 kernel doesn't call kfree_skb() from
> irqs_disabled, can I safely revert this entire change?

Not if you mean dropping skbufhead-raw-lock.patch.

We can drop `tofree_queue' and everything related to it. We need to
keep the `raw_lock' and the `rps_lock()' hunks for
`sd->input_pkt_queue'. The other queue, `sd->process_queue', is
protected by local_bh_disable() so these hunks can be dropped in the
more recent RT versions with the re-written softirq code
(v5.0.19-rt10+).

> Is it safe to call kfree_skb() from local_bh_disable()?

of course it is.

> I'm assuming it is, but just want to clarify. I'll be continuing
> merging latest stable (with this revert), but please yell if you think
> it will break?
>
> Thanks!
> 
> -- Steve

Sebastian