From: Daniel Lezcano <daniel.lezcano@linaro.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: rjw@rjwysocki.net, lukasz.luba@arm.com, robh@kernel.org,
heiko@sntech.de, arnd@linaro.org, linux-kernel@vger.kernel.org,
linux-pm@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
"open list:GENERIC INCLUDE/ASM HEADER FILES"
<linux-arch@vger.kernel.org>
Subject: Re: [PATCH v5 1/6] powercap/drivers/dtpm: Move dtpm table from init to data section
Date: Fri, 7 Jan 2022 14:15:52 +0100 [thread overview]
Message-ID: <556eca9c-4ce8-1c79-cc6d-08d0ec603bd4@linaro.org> (raw)
In-Reply-To: <CAPDyKFpY4i0Mtb==8zknsuG0HdhPW2fXFvEN+AJScVmT65A-ow@mail.gmail.com>
On 31/12/2021 14:33, Ulf Hansson wrote:
> On Sat, 18 Dec 2021 at 14:00, Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
>>
>> The dtpm table is used to let the different dtpm backends to register
>> their setup callbacks in a single place and preventing to export
>> multiple functions all around the kernel. That allows the dtpm code to
>> be self-encapsulated.
>
> Well, that's not entirely true. The dtpm code and its backends (or
> ops, whatever we call them) are already maintained from a single
> place, the /drivers/powercap/* directory. I assume we intend to keep
> it like this going forward too, right?
>
> That is also what patch4 with the devfreq backend continues to conform to.
>
>>
>> The dtpm hierarchy will be passed as a parameter by a platform
>> specific code and that will lead to the creation of the different dtpm
>> nodes.
>>
>> The function creating the hierarchy could be called from a module at
>> init time or when it is loaded. However, at this moment the table is
>> already freed as it belongs to the init section and the creation will
>> lead to a invalid memory access.
>>
>> Fix this by moving the table to the data section.
>
> With the above said, I find it a bit odd to put a table in the data
> section like this. Especially, since the only remaining argument for
> why, is to avoid exporting functions, which isn't needed anyway.
>
> I mean, it would be silly if we should continue to put subsystem
> specific tables in here, to just let them contain a set of subsystem
> specific callbacks.
So I tried to change the approach and right now I was not able to find
an alternative keeping the code self-encapsulate and without introducing
cyclic dependencies.
I suggest to keep the patch as it is and double check if it makes sense
to change it after adding more dtpm backends
Alternatively I can copy the table to a dynamically allocated table.
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>
> Kind regards
> Uffe
>
>> ---
>> include/asm-generic/vmlinux.lds.h | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
>> index 42f3866bca69..50d494d94d6c 100644
>> --- a/include/asm-generic/vmlinux.lds.h
>> +++ b/include/asm-generic/vmlinux.lds.h
>> @@ -362,7 +362,8 @@
>> BRANCH_PROFILE() \
>> TRACE_PRINTKS() \
>> BPF_RAW_TP() \
>> - TRACEPOINT_STR()
>> + TRACEPOINT_STR() \
>> + DTPM_TABLE()
>>
>> /*
>> * Data section helpers
>> @@ -723,7 +724,6 @@
>> ACPI_PROBE_TABLE(irqchip) \
>> ACPI_PROBE_TABLE(timer) \
>> THERMAL_TABLE(governor) \
>> - DTPM_TABLE() \
>> EARLYCON_TABLE() \
>> LSM_TABLE() \
>> EARLY_LSM_TABLE() \
>> --
>> 2.25.1
>>
--
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next prev parent reply other threads:[~2022-01-07 13:15 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-18 13:00 [PATCH v5 0/6] powercap/drivers/dtpm: Create the dtpm hierarchy Daniel Lezcano
2021-12-18 13:00 ` [PATCH v5 1/6] powercap/drivers/dtpm: Move dtpm table from init to data section Daniel Lezcano
2021-12-31 13:33 ` Ulf Hansson
2022-01-04 8:57 ` Daniel Lezcano
2022-01-07 13:15 ` Daniel Lezcano [this message]
2022-01-07 14:49 ` Ulf Hansson
2022-01-10 13:33 ` Daniel Lezcano
2021-12-18 13:00 ` [PATCH v5 2/6] powercap/drivers/dtpm: Add hierarchy creation Daniel Lezcano
2021-12-31 13:45 ` Ulf Hansson
2022-01-05 16:00 ` Daniel Lezcano
2022-01-07 15:54 ` Ulf Hansson
2022-01-10 15:55 ` Daniel Lezcano
2022-01-11 8:28 ` Ulf Hansson
2022-01-11 17:52 ` Daniel Lezcano
2022-01-12 12:00 ` Ulf Hansson
2022-01-14 19:15 ` Daniel Lezcano
2021-12-18 13:00 ` [PATCH v5 3/6] powercap/drivers/dtpm: Add CPU DT initialization support Daniel Lezcano
2021-12-31 13:46 ` Ulf Hansson
2021-12-18 13:00 ` [PATCH v5 4/6] powercap/drivers/dtpm: Add dtpm devfreq with energy model support Daniel Lezcano
2021-12-18 13:00 ` [PATCH v5 5/6] rockchip/soc/drivers: Add DTPM description for rk3399 Daniel Lezcano
2021-12-31 13:57 ` Ulf Hansson
2022-01-04 9:29 ` Geert Uytterhoeven
2022-01-05 9:21 ` Daniel Lezcano
2022-01-05 11:25 ` Daniel Lezcano
2021-12-18 13:00 ` [PATCH v5 6/6] qcom/soc/drivers: Add DTPM description for sdm845 Daniel Lezcano
2021-12-18 19:47 ` Steev Klimaszewski
2021-12-18 20:11 ` Daniel Lezcano
2021-12-19 18:44 ` Steev Klimaszewski
2021-12-19 20:27 ` Daniel Lezcano
2022-01-07 19:27 ` Bjorn Andersson
2022-01-07 22:07 ` Daniel Lezcano
2022-01-07 23:51 ` Bjorn Andersson
2021-12-23 13:20 ` [PATCH v5 0/6] powercap/drivers/dtpm: Create the dtpm hierarchy Daniel Lezcano
2021-12-23 13:32 ` Ulf Hansson
2021-12-23 13:42 ` Daniel Lezcano
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