Hi Reinette/Tony,
On 10/14/24 21:39, wrote:
> Hi Babu,
>
> On 10/14/24 9:35 AM, Moger, Babu wrote:
>> On 12/31/69 18:00, Luck, Tony wrote:
>
>>>
>>> It is still the case that callers don't care about the return value.
>>
>> That is correct.
>>
>
> Are you planning to change this? I think Tony has a good point that since
> assignment failures do not matter it unnecessarily complicates the code to
> have rdtgroup_assign_cntrs() return failure.
>
> I also think the internals of rdtgroup_assign_cntrs() deserve a closer look.
> I assume that error handling within rdtgroup_assign_cntrs() was created with
> ABMC in mind. When only considering ABMC then the only reason why
> rdtgroup_assign_cntr_event() could fail is if the system ran out of counters
> and then indeed it makes no sense to attempt another call to rdtgroup_assign_cntr_event().
>
> Now that the resctrl fs/arch split is clear the implementation does indeed expose
> another opportunity for failure ... if the arch callback, resctrl_arch_config_cntr()
> fails. It could thus be possible for the first rdtgroup_assign_cntr_event() to fail
> while the second succeeds. Earlier [1], Tony suggested to, within rdtgroup_assign_cntrs(),
> remove the local ret variable and have it return void. This sounds good to me.
> When doing so a function comment explaining the usage will be helpful.
>
> I also think that rdtgroup_unassign_cntrs() deserves similar scrutiny. Even more
> so since I do not think that the second rdtgroup_unassign_cntr_event()
> should be prevented from running if the first rdtgroup_unassign_cntr_event() fails.
Sounds fine with me. Now it will look like this below.
static void rdtgroup_assign_cntrs(struct rdtgroup *rdtgrp)
{
struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
if (!resctrl_arch_mbm_cntr_assign_enabled(r))
return;
if (is_mbm_total_enabled())
rdtgroup_assign_cntr_event(r, rdtgrp, NULL, QOS_L3_MBM_TOTAL_EVENT_ID);
if (is_mbm_local_enabled())
rdtgroup_assign_cntr_event(r, rdtgrp, NULL, QOS_L3_MBM_LOCAL_EVENT_ID);
}
/*
* Called when a group is deleted. Counters are unassigned if it was in
* assigned state.
*/
static void rdtgroup_unassign_cntrs(struct rdtgroup *rdtgrp)
{
struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
if (!resctrl_arch_mbm_cntr_assign_enabled(r))
return;
if (is_mbm_total_enabled())
rdtgroup_unassign_cntr_event(r, rdtgrp, NULL, QOS_L3_MBM_TOTAL_EVENT_ID);
if (is_mbm_local_enabled())
rdtgroup_unassign_cntr_event(r, rdtgrp, NULL, QOS_L3_MBM_LOCAL_EVENT_ID);
}
>
> Reinette
>
> [1] https://lore.kernel.org/all/ZwldvDBjEA3TSw2k@xxxxxxxxxxxxxxxxxxxxxxxxx/
>
--
Thanks
Babu Moger
