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arm_mpam: resctrl: Make read_mon_cdp_safe() self consistent

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When read_mon_cdp_safe() is called with cdp_enabled equal to false then the
reading returned in val is the sum of the monitor values for the given
component. However, when cdp_enabled equal to true it is again the sum of
the monitor values but with the initial value of val also added. Both
resctrl_arch_cntr_read() and resctrl_arch_rmid_read() call
read_mon_cdp_safe() and are documented to return the val directly without
consideration of the older value.

The val is always zeroed before read_mon_cdp_safe() is called except in
__check_limbo() and __l3_mon_event_count_sum() but the latter is not
relevant on MPAM systems.  The extra accumulation in __check_limbo() means
when there are multiple RMIDs in limbo some of them may be marked dirty
when they are already clean.

Change the cdp_enabled equals true case to match the false case.

Fixes: fb56b29932 ("arm_mpam: resctrl: Add resctrl_arch_rmid_read()")
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Tested-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: James Morse <james.morse@arm.com>
[morse: fixed commit message indenting and removed stale description]
Signed-off-by: James Morse <james.morse@arm.com>
This commit is contained in:
Ben Horgan 2026-09-17 15:56:14 +01:00 committed by James Morse
parent 724eae25d1
commit 09ff5358c6
1 changed files with 1 additions and 1 deletions
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2
drivers/resctrl/mpam_resctrl.c
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@ -497,7 +497,7 @@ static int read_mon_cdp_safe(struct mpam_resctrl_mon *mon, struct mpam_component
if (err)
return err;
*val += code_val + data_val;
*val = code_val + data_val;
return 0;
}