From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: linuxppc-dev@ozlabs.org, sbest@us.ibm.com,
Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>,
paulus@samba.org, anton@samba.org
Subject: Re: [PATCH 1/1] Punch a hole in /dev/mem for librtas
Date: Mon, 05 Dec 2011 10:18:21 +1100 [thread overview]
Message-ID: <1323040701.11728.27.camel@pasglop> (raw)
In-Reply-To: <144CAEA6-C129-4935-B6D1-A7D6F24530A5@kernel.crashing.org>
On Sat, 2011-12-03 at 04:22 +0100, Segher Boessenkool wrote:
> > +static inline int page_is_rtas_user_buf(unsigned long pfn)
> > +{
> > + unsigned long paddr = (pfn << PAGE_SHIFT);
> > + if (paddr >= rtas_rmo_buf && paddr < (rtas_rmo_buf +
> > RTAS_RMOBUF_MAX))
>
> It probably cannot overflow with actual values of rtas_rmo_buf
> and RTAS_RMOBUF_MAX, but otherwise it is an incorrect test;
> please write
>
> if (paddr >= rtas_rmo_buf && paddr - rtas_rmo_buf < RTAS_RMOBUF_MAX)
>
> (and, _MAX? Shouldn't it be the actual size here? Or is _MAX
> just a confusing name :-) )
The original code is a lot more readable and perfectly correct for all
possible values of rtas_rmo_buf :-)
Cheers,
Ben.
next prev parent reply other threads:[~2011-12-04 23:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-02 22:26 [PATCH 1/1] Punch a hole in /dev/mem for librtas Sukadev Bhattiprolu
2011-12-03 3:22 ` Segher Boessenkool
2011-12-04 23:18 ` Benjamin Herrenschmidt [this message]
2011-12-05 7:58 ` Segher Boessenkool
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