[PATCH v6 14/42] x86/resctrl: Add an arch helper to reset one resource

[James Morse <james.morse@arm.com>]

On umount(), resctrl resets each resource back to its default
configuration. It only ever does this for all resources in one go.

reset_all_ctrls() is architecture specific as it works with struct
rdt_hw_resource.

Make reset_all_ctrls() an arch helper that resets one resource.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v5:
 * Move the arch/fs split into the for-each loop at Reinette's suggestion.
 * Dropped a bunch of tags and rewrote the commit message.

Changes since v1:
 * Rename the for_each_capable_rdt_resource() introduced in the new
   function resctrl_arch_reset_resources(), back to
   for_each_alloc_capable_rdt_resource() as it was in the original code.

   The change looked unintentional; and presumably a resource that does
   not support resource allocation doesn't have any properties to
   reset...
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 9 +++++----
 include/linux/resctrl.h                | 9 +++++++++
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index b2dad689e780..9eb57ebb36c6 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2867,7 +2867,7 @@ static int rdt_init_fs_context(struct fs_context *fc)
 	return 0;
 }
 
-static int reset_all_ctrls(struct rdt_resource *r)
+void resctrl_arch_reset_all_ctrls(struct rdt_resource *r)
 {
 	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
 	struct rdt_hw_ctrl_domain *hw_dom;
@@ -2896,7 +2896,7 @@ static int reset_all_ctrls(struct rdt_resource *r)
 		smp_call_function_any(&d->hdr.cpu_mask, rdt_ctrl_update, &msr_param, 1);
 	}
 
-	return 0;
+	return;
 }
 
 /*
@@ -3015,9 +3015,10 @@ static void rdt_kill_sb(struct super_block *sb)
 
 	rdt_disable_ctx();
 
-	/*Put everything back to default values. */
+	/* Put everything back to default values. */
 	for_each_alloc_capable_rdt_resource(r)
-		reset_all_ctrls(r);
+		resctrl_arch_reset_all_ctrls(r);
+
 	rmdir_all_sub();
 	rdt_pseudo_lock_release();
 	rdtgroup_default.mode = RDT_MODE_SHAREABLE;
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 74cfd48e69ee..4444bc05e39c 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -414,6 +414,15 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_mon_domain *d,
  */
 void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_mon_domain *d);
 
+/**
+ * resctrl_arch_reset_all_ctrls() - Reset the control for each CLOSID to its
+ *				    default.
+ * @r:		The resctrl resource to reset.
+ *
+ * This can be called from any CPU.
+ */
+void resctrl_arch_reset_all_ctrls(struct rdt_resource *r);
+
 extern unsigned int resctrl_rmid_realloc_threshold;
 extern unsigned int resctrl_rmid_realloc_limit;
 
-- 
2.39.2