Re: [PATCH v2 07/18] x86/resctrl: Move CLOSID/RMID matching and setting to use helpers

[Reinette Chatre]

Hi James,

On 3/6/2023 3:32 AM, James Morse wrote:
> On 02/02/2023 23:47, Reinette Chatre wrote:
>> On 1/13/2023 9:54 AM, James Morse wrote:
>>
>> ...
>>
>>> @@ -567,19 +579,14 @@ static int __rdtgroup_move_task(struct task_struct *tsk,
>>>  	 * For monitor groups, can move the tasks only from
>>>  	 * their parent CTRL group.
>>>  	 */
>>> -
>>> -	if (rdtgrp->type == RDTCTRL_GROUP) {
>>> -		WRITE_ONCE(tsk->closid, rdtgrp->closid);
>>> -		WRITE_ONCE(tsk->rmid, rdtgrp->mon.rmid);
>>> -	} else if (rdtgrp->type == RDTMON_GROUP) {
>>> -		if (rdtgrp->mon.parent->closid == tsk->closid) {
>>> -			WRITE_ONCE(tsk->rmid, rdtgrp->mon.rmid);
>>> -		} else {
>>> -			rdt_last_cmd_puts("Can't move task to different control group\n");
>>> -			return -EINVAL;
>>> -		}
>>> +	if (rdtgrp->type == RDTMON_GROUP &&
>>> +	    !resctrl_arch_match_closid(tsk, rdtgrp->mon.parent->closid)) {
>>> +		rdt_last_cmd_puts("Can't move task to different control group\n");
>>> +		return -EINVAL;
>>>  	}
>>>  
>>> +	resctrl_arch_set_closid_rmid(tsk, rdtgrp->closid, rdtgrp->mon.rmid);
>>
>> This does not use the intended closid when rdtgrp->type == RDTMON_GROUP.
> 
> Yes, it should be rdtgrp->mon.parent->closid.
> 
> rdtgroup_mkdir_mon() initialises them to be the same

Even so, I do find the code to be confusing when it jumps from one to
the other within the same function.

>, I guess its Peter's monitor-group
> rename that means this could get the wrong value?
> 
> I've fixed it as:
> ---------%<---------
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index c7392d10dc5b..30d8961b833c 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -585,7 +585,12 @@ static int __rdtgroup_move_task(struct task_struct *tsk,
>                 return -EINVAL;
>         }
> 
> -       resctrl_arch_set_closid_rmid(tsk, rdtgrp->closid, rdtgrp->mon.rmid);
> +       if (rdtgrp->type == RDTMON_GROUP)
> +               resctrl_arch_set_closid_rmid(tsk, rdtgrp->mon.parent->closid,
> +                                            rdtgrp->mon.rmid);
> +       else
> +               resctrl_arch_set_closid_rmid(tsk, rdtgrp->closid,
> +                                            rdtgrp->mon.rmid);
> 
>         /*
>          * Ensure the task's closid and rmid are written before determining if
> ---------%<---------
> 
> 

ok, thank you.

Reinette