linux-kernel - [patch 11/12] x86/resctrl: use smp_call_function_single

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Date: Tue, 06 Feb 2024 15:49:22 -0300
From: Marcelo Tosatti <mtosatti@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Daniel Bristot de Oliveira <bristot@...nel.org>,
 Juri Lelli <juri.lelli@...hat.com>,
 Valentin Schneider <vschneid@...hat.com>,
 Frederic Weisbecker <frederic@...nel.org>,
 Leonardo Bras <leobras@...hat.com>,
 Peter Zijlstra <peterz@...radead.org>,
 Thomas Gleixner <tglx@...utronix.de>,
 Marcelo Tosatti <mtosatti@...hat.com>
Subject: [patch 11/12] x86/resctrl: use smp_call_function_single_fail

Convert update_task_closid_rmid from smp_call_function_single
to smp_call_func_single_fail, which will fail in case
the target CPU is tagged as block interference CPU.

Signed-off-by: Marcelo Tosatti <mtosatti@...hat.com>

Index: linux-isolation/arch/x86/kernel/cpu/resctrl/rdtgroup.c
===================================================================
--- linux-isolation.orig/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ linux-isolation/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -26,6 +26,7 @@
 #include <linux/slab.h>
 #include <linux/task_work.h>
 #include <linux/user_namespace.h>
+#include <linux/sched/isolation.h>
 
 #include <uapi/linux/magic.h>
 
@@ -551,12 +552,20 @@ static void _update_task_closid_rmid(voi
 		resctrl_sched_in(task);
 }
 
-static void update_task_closid_rmid(struct task_struct *t)
+static int update_task_closid_rmid(struct task_struct *t)
 {
-	if (IS_ENABLED(CONFIG_SMP) && task_curr(t))
-		smp_call_function_single(task_cpu(t), _update_task_closid_rmid, t, 1);
-	else
+	int idx, ret = 0;
+
+	if (IS_ENABLED(CONFIG_SMP) && task_curr(t)) {
+		idx = block_interf_srcu_read_lock();
+		ret = smp_call_function_single_fail(task_cpu(t),
+						    _update_task_closid_rmid,
+						    t, 1);
+		block_interf_srcu_read_unlock(idx);
+	} else
 		_update_task_closid_rmid(t);
+
+	return ret;
 }
 
 static int __rdtgroup_move_task(struct task_struct *tsk,
@@ -604,9 +613,7 @@ static int __rdtgroup_move_task(struct t
 	 * group go into effect. If the task is not current, the MSR will be
 	 * updated when the task is scheduled in.
 	 */
-	update_task_closid_rmid(tsk);
-
-	return 0;
+	return update_task_closid_rmid(tsk);
 }
 
 static bool is_closid_match(struct task_struct *t, struct rdtgroup *r)