linux-kernel - RE: [PATCH] rcu: Narrow early boot window of illegal synchronous grace periods

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Date:   Mon, 16 Jan 2017 01:57:25 +0000
From:   "Zheng, Lv" <lv.zheng@...el.com>
To:     Borislav Petkov <bp@...en8.de>,
        "Rafael J. Wysocki" <rafael@...nel.org>
CC:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "stan.kain@...il.com" <stan.kain@...il.com>,
        "waffolz@...mail.com" <waffolz@...mail.com>,
        Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        "mathieu.desnoyers@...icios.com" <mathieu.desnoyers@...icios.com>,
        "jiangshanlai@...il.com" <jiangshanlai@...il.com>,
        Ingo Molnar <mingo@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: RE: [PATCH] rcu: Narrow early boot window of illegal synchronous
 grace periods

Hi,

> From: Borislav Petkov [mailto:bp@...en8.de]
> Subject: Re: [PATCH] rcu: Narrow early boot window of illegal synchronous grace periods
> 
> On Sat, Jan 14, 2017 at 01:27:40PM +0100, Rafael J. Wysocki wrote:
> > OK, so this fixes the problem with synchronize_rcu_expedited() in
> > acpi_os_map_cleanup(), right?
> 
> Yeah.
> 
> > I wonder if the ACPI-specific fix is still needed, then?
> 
> It is not strictly necessary. If you still think it would be better to
> have it regardless, you could pick it up. I.e., making ACPI more robust,
> yadda yadda.
> 
> I dunno, though, perhaps it is only complicating the code unnecessarily
> and then can be safely ignored with a mental note for future freezes.

Glad to see it fixed inside of the API provider.

IMO, ACPI fix is unnecessary as ACPI is just a user of the RCU APIs.
And it's pointless to add special checks in the user side in order to use one of them.

Thanks and best regards
Lv

> 
> --
> Regards/Gruss,
>     Boris.
> 
> Good mailing practices for 400: avoid top-posting and trim the reply.