linux-kernel - Re: [PATCH] tick/broadcast-hrtimer : Fix suspicious RCU usage in idle loop

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]

Date:	Mon, 2 Mar 2015 15:53:54 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
Cc:	tglx@...utronix.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tick/broadcast-hrtimer : Fix suspicious RCU usage in
 idle loop

On Thu, Feb 26, 2015 at 08:52:02AM +0530, Preeti U Murthy wrote:
> The hrtimer mode of broadcast queues hrtimers in the idle entry
> path so as to wakeup cpus in deep idle states. 

Callgraph please...

> hrtimer_{start/cancel}
> functions call into tracing which uses RCU. But it is not legal to call
> into RCU in cpuidle because it is one of the quiescent states. Hence
> protect this region with RCU_NONIDLE which informs RCU that the cpu
> is momentarily non-idle.

It it not clear to me that every user of bc_set_next() is from IDLE.
>From what I can tell it ends up being clockevents_program_event() and
that is called quite a lot.

Why is bc_set_next() a good function to annotate?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/