On 31/12/2021 14:33, Ulf Hansson wrote: > On Sat, 18 Dec 2021 at 14:00, Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> 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@xxxxxxxxxx> > > 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 >> -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog
