[PATCH v8 23/24] x86/resctrl: Move domain helper migration into resctrl_offline_cpu()

[James Morse]

When a CPU is taken offline the resctrl filesystem code needs to check
if it was the CPU nominated to perform the periodic overflow and limbo
work. If so, another CPU needs to be chosen to do this work.

This is currently done in core.c, mixed in with the code that removes
the CPU from the domain's mask, and potentially free()s the domain.

Move the migration of the overflow and limbo helpers into the filesystem
code, into resctrl_offline_cpu(). As resctrl_offline_cpu() runs before
the architecture code has removed the CPU from the domain mask, the
callers need to be told which CPU is being removed, to avoid picking
it as the new CPU. This uses the exclude_cpu feature previously
added.

Signed-off-by: James Morse <james.morse@xxxxxxx>
Tested-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxx>
Tested-by: Peter Newman <peternewman@xxxxxxxxxx>
Tested-by: Babu Moger <babu.moger@xxxxxxx>
Reviewed-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxx>
Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Reviewed-by: Babu Moger <babu.moger@xxxxxxx>
---
Changes since v5:
 * Changed fir tree order of variables.
 * Added mon-capable check for cpu offline.
---
 arch/x86/kernel/cpu/resctrl/core.c     | 16 ----------------
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 18 ++++++++++++++++++
 2 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 65540acd59de..c943cb78b2a1 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -582,22 +582,6 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)
 
 		return;
 	}
-
-	if (r == &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl) {
-		if (is_mbm_enabled() && cpu == d->mbm_work_cpu) {
-			cancel_delayed_work(&d->mbm_over);
-			/*
-			 * temporary: exclude_cpu=-1 as this CPU has already
-			 * been removed by cpumask_clear_cpu()d
-			 */
-			mbm_setup_overflow_handler(d, 0, RESCTRL_PICK_ANY_CPU);
-		}
-		if (is_llc_occupancy_enabled() && cpu == d->cqm_work_cpu &&
-		    has_busy_rmid(d)) {
-			cancel_delayed_work(&d->cqm_limbo);
-			cqm_setup_limbo_handler(d, 0, RESCTRL_PICK_ANY_CPU);
-		}
-	}
 }
 
 static void clear_closid_rmid(int cpu)
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 958f73974860..f007c488fa31 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -4034,7 +4034,9 @@ static void clear_childcpus(struct rdtgroup *r, unsigned int cpu)
 
 void resctrl_offline_cpu(unsigned int cpu)
 {
+	struct rdt_resource *l3 = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
 	struct rdtgroup *rdtgrp;
+	struct rdt_domain *d;
 
 	lockdep_assert_held(&rdtgroup_mutex);
 
@@ -4044,6 +4046,22 @@ void resctrl_offline_cpu(unsigned int cpu)
 			break;
 		}
 	}
+
+	if (!l3->mon_capable)
+		return;
+
+	d = get_domain_from_cpu(cpu, l3);
+	if (d) {
+		if (is_mbm_enabled() && cpu == d->mbm_work_cpu) {
+			cancel_delayed_work(&d->mbm_over);
+			mbm_setup_overflow_handler(d, 0, cpu);
+		}
+		if (is_llc_occupancy_enabled() && cpu == d->cqm_work_cpu &&
+		    has_busy_rmid(d)) {
+			cancel_delayed_work(&d->cqm_limbo);
+			cqm_setup_limbo_handler(d, 0, cpu);
+		}
+	}
 }
 
 /*
-- 
2.20.1