linux-kernel - Re: [PATCH] PM / OPP: fix debugfs files for 64-bit

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Date:	Wed, 7 Oct 2015 22:06:59 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Nishanth Menon <nm@...com>, Len Brown <len.brown@...el.com>,
	Arnd Bergmann <arnd@...db.de>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-kernel@...r.kernel.org, Pavel Machek <pavel@....cz>,
	Dmitry Torokhov <dtor@...omium.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] PM / OPP: fix debugfs files for 64-bit

On 07-10-15, 17:33, Russell King - ARM Linux wrote:
> Don't you even think about doing that - that's totally broken no matter
> what, and this is a good example of why casts are Bad.
> 
> debugfs_create_u64() will create a debugfs object that will want to
> access a 64-bit value, but the value pointed to is only 32-bit.  The
> net result is that the debugfs file ends up reading or writing the
> neigbouring 32-bits, which may potentially be unaligned.

Yeah, that's what I was also saying. Its broken.

> The variable pointed to for debugfs_create_u64() must be a 64-bit
> value.  No casts allowed.
> 
> An alternative would be to have debugfs_create_ulong()

And that's what I suggested.

-- 
viresh
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