From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Tomasz Nowicki <tomasz.nowicki@linaro.org>
Cc: Hanjun Guo <hanjun.guo@linaro.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Mark Rutland <mark.rutland@arm.com>, Olof Johansson <olof@lixom.net>,
        Grant Likely <grant.likely@linaro.org>,
        Will Deacon <will.deacon@arm.com>,
        Graeme Gregory <graeme.gregory@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>, Sudeep Holla <Sudeep.Holla@arm.com>,
        Jon Masters <jcm@redhat.com>, Jason Cooper <jason@lakedaemon.net>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Mark Brown <broonie@kernel.org>, Rob Herring <robh@kernel.org>,
        Robert Richter <rric@kernel.org>, Lv Zheng <lv.zheng@intel.com>,
        Robert Moore <robert.moore@intel.com>,
        Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
        Liviu Dudau <Liviu.Dudau@arm.com>,
        Randy Dunlap <rdunlap@infradead.org>, Charles.Garcia-Tobin@arm.com,
        Kangkang.Shen@huawei.com, linux-acpi@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linaro-acpi@lists.linaro.org
Subject: Re: [PATCH v5 03/18] ACPI / table: Count matched and successfully parsed entries without specifying max entries
Date: Mon, 24 Nov 2014 16:37:19 +0100
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On Monday, November 24, 2014 04:01:24 PM Tomasz Nowicki wrote:
> On 24.11.2014 16:16, Rafael J. Wysocki wrote:
> > On Monday, November 24, 2014 09:34:24 AM Tomasz Nowicki wrote:
> >> On 24.11.2014 02:45, Rafael J. Wysocki wrote:
> >>> On Friday, October 17, 2014 09:36:59 PM Hanjun Guo wrote:
> >>>> From: Tomasz Nowicki <tomasz.nowicki@linaro.org>
> >>>>
> >>>> It is very useful to traverse all available table entries without max
> >>>> number of expected entries type. Current acpi_parse_entries()
> >>>> implementation gives that feature but it does not count those entries,
> >>>> it returns 0 instead, so fix it to count matched and successfully
> >>>> entries and return it.
> >>>
> >>> Hmm.  I guess that the goal is for count to only be incremented when the
> >>> condition is satisfied entirely, while without the patch it may be incremented
> >>> even if that isn't the case.
> >>
> >> That would be our goal if patch would look like:
> >> -		    && (!max_entries || count++ < max_entries))
> >> +		    && (!max_entries && count++ < max_entries)) {
> >> but then we can not walk through all available entries (with max_entries==0)
> >
> > No, that's not what I was trying to say. :-)
> >
> >>>
> >>> I'm not sure how that is related to the above paragraph, however.
> >>>
> >>
> >> Previous changelog is not clear, let me rewrite it:
> >>
> >> acpi_parse_entries() allows to traverse all available table entries (aka
> >> subtables) by passing max_entries parameter equal to 0. But for that use
> >> case acpi_parse_entries() does not inform caller how many entries were
> >> matched and for how many entries handler was run against. That patch is
> >> going to fix it.
> >
> > Do I understand correctly that count is only ever incremented by current code
> > if max_entries is different from 0?
> 
> Right. Currently "count" is incremented only if max_entries > 0.

So can you say that in the changelog, please?

Something like:

"acpi_parse_entries() allows to traverse all available table entries (aka
 subtables) by passing max_entries parameter equal to 0, but since its count
 variable is only incremented if max_entries is not 0, the function always
 returns 0 for max_entries equal to 0.  It would be more useful if it returned
 the number of entries matched instead, so make it increment count in that
 case too".

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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