linux-kernel - Re: [PATCH v6 1/1] MIPS: Fix idle VS timer enqueue

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: <Z9rPVHop5Ob5nAdc@p200300d06f3e987545685175b554ae65.dip0.t-ipconnect.de>
Date: Wed, 19 Mar 2025 15:06:12 +0100
From: Frederic Weisbecker <frederic@...nel.org>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: Marco Crivellari <marco.crivellari@...e.com>,
	linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Huacai Chen <chenhuacai@...nel.org>,
	"Maciej W . Rozycki" <macro@...am.me.uk>
Subject: Re: [PATCH v6 1/1] MIPS: Fix idle VS timer enqueue

Le Wed, Mar 19, 2025 at 12:07:07PM +0100, Thomas Bogendoerfer a écrit :
> On Sat, Mar 15, 2025 at 08:40:02PM +0100, Marco Crivellari wrote:
> > MIPS re-enables interrupts on its idle routine and performs
> > a TIF_NEED_RESCHED check afterwards before putting the CPU to sleep.
> > 
> > The IRQs firing between the check and the 'wait' instruction may set the
> > TIF_NEED_RESCHED flag. In order to deal with this possible race, IRQs
> > interrupting __r4k_wait() rollback their return address to the
> > beginning of __r4k_wait() so that TIF_NEED_RESCHED is checked
> > again before going back to sleep.
> > 
> > However idle IRQs can also queue timers that may require a tick
> > reprogramming through a new generic idle loop iteration but those timers
> > would go unnoticed here because __r4k_wait() only checks
> > TIF_NEED_RESCHED. It doesn't check for pending timers.
> 
> can you give a commit ID, when this change got introduced ?

That would be:

     Fixes: c65a5480ff29 ("[MIPS] Fix potential latency problem due to non-atomic cpu_wait.")