[v2,09/12] task_isolation: net: don't flush backlog on CPUs running isolated tasks

Message ID 541d4f371541b5085fb3519ae749d9ed8f056aeb.camel@marvell.com
State New
Headers show
  • Untitled series #43108
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Commit Message

Alex Belits March 8, 2020, 3:54 a.m.
From: Yuri Norov <ynorov@marvell.com>

If CPU runs isolated task, there's no any backlog on it, and
so we don't need to flush it. Currently flush_all_backlogs()
enqueues corresponding work on all CPUs including ones that run
isolated tasks. It leads to breaking task isolation for nothing.

In this patch, backlog flushing is enqueued only on non-isolated CPUs.

Signed-off-by: Yuri Norov <ynorov@marvell.com>

[abelits@marvell.com: use safe task_isolation_on_cpu() implementation]
Signed-off-by: Alex Belits <abelits@marvell.com>

 net/core/dev.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)



diff --git a/net/core/dev.c b/net/core/dev.c
index c6c985fe7b1b..6d32abb1f06d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -74,6 +74,7 @@ 
 #include <linux/cpu.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
+#include <linux/isolation.h>
 #include <linux/hash.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
@@ -5518,9 +5519,12 @@  static void flush_all_backlogs(void)
-	for_each_online_cpu(cpu)
+	for_each_online_cpu(cpu) {
+		if (task_isolation_on_cpu(cpu))
+			continue;
 		queue_work_on(cpu, system_highpri_wq,
 			      per_cpu_ptr(&flush_works, cpu));
+	}
 		flush_work(per_cpu_ptr(&flush_works, cpu));