[PATCH] kernel: disable CONFIG_RCU_EXPERT and friends

[Hauke Mehrtens]

On 8/22/21 2:17 PM, Rui Salvaterra wrote:
> Hi, Hauke,
> 
> On Sun, 22 Aug 2021 at 10:20, Hauke Mehrtens <hauke at hauke-m.de> wrote:
>>
>> There are also some targets which explicitly unset CONFIG_RCU_EXPERT:
> 
> [snipped]
> 
>> This should be removed from the target config file.
> 
> Sure thing, I'll clean up the targets and fold the changes into this patch.
> 
>> CONFIG_RCU_STALL_COMMON=y and CONFIG_RCU_NEED_SEGCBLIST=y are also set
>> in most target configurations. Should we move them to the generic
>> configuration?
> 
> Good question. Those symbols are only relevant when tree RCU is
> enabled, which is everything except non-preemptible, non-SMP kernels.
> We don't enable preemption, so basically these will only be relevant
> for SMP devices. That said, I believe moving them to the generic
> kconfigs is the right thing to do. Do you agree?

Both options are hidden anyway, so we can manually change them:

config RCU_STALL_COMMON
	def_bool ( TREE_RCU || PREEMPT_RCU )
	help

config RCU_NEED_SEGCBLIST
	def_bool ( TREE_RCU || PREEMPT_RCU || TREE_SRCU )

They are automatically activated when the dependencies are satisfied.

I would add this to the generic kernel configurations and remove the 
individual ones in a separate patch:
CONFIG_RCU_STALL_COMMON=y
CONFIG_RCU_NEED_SEGCBLIST=y

Hauke
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