linux-kernel - Re: [PATCH V4 1/2] ACPI / EC: Fix broken 64bit big-endian users of 'global

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Message-ID: <CAKohpok2Z2m7GZt1GzZzofeHEioF=XJEq8YVgtY=VtS9tmpb_Q@mail.gmail.com>
Date:	Fri, 25 Sep 2015 13:25:49 -0700
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Johannes Berg <johannes@...solutions.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linaro Kernel Mailman List <linaro-kernel@...ts.linaro.org>,
	QCA ath9k Development <ath9k-devel@....qualcomm.com>,
	Intel Linux Wireless <ilw@...ux.intel.com>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Linux ACPI <linux-acpi@...r.kernel.org>,
	"open list:BLUETOOTH DRIVERS" <linux-bluetooth@...r.kernel.org>,
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	<alsa-devel@...a-project.org>
Subject: Re: [PATCH V4 1/2] ACPI / EC: Fix broken 64bit big-endian users of 'global_lock'

On 25 September 2015 at 13:33, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> You're going to change that into bool in the next patch, right?

Yeah.

> So what if bool is a byte and the field is not word-aligned

Its between two 'unsigned long' variables today, and the struct isn't packed.
So, it will be aligned, isn't it?

> and changing
> that byte requires a read-modify-write.  How do we ensure that things remain
> consistent in that case?

I didn't understood why a read-modify-write is special here? That's
what will happen
to most of the non-word-sized fields anyway?

Probably I didn't understood what you meant..

--
viresh
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