linux-kernel - [PATCH 2/2] S390 topology: don't use kthread() for arch_reinit_sched

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Message-ID: <20080629165132.GA11218@tv-sign.ru>
Date:	Sun, 29 Jun 2008 20:51:32 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Gautham R Shenoy <ego@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Max Krasnyansky <maxk@...lcomm.com>, Paul Jackson <pj@....com>,
	Paul Menage <menage@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Vegard Nossum <vegard.nossum@...il.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] S390 topology: don't use kthread() for arch_reinit_sched_domains()

Untested, needs Heiko's ack.

Now that it is safe to use get_online_cpus() we can revert

	[S390] cpu topology: Fix possible deadlock.
	commit: fd781fa25c9e9c6fd1599df060b05e7c4ad724e5

and call arch_reinit_sched_domains() directly from topology_work_fn().

Signed-off-by: Oleg Nesterov <oleg@...sign.ru>

--- 26-rc2/arch/s390/kernel/topology.c~WQ_5_TOPOLOGY	2008-05-18 15:43:28.000000000 +0400
+++ 26-rc2/arch/s390/kernel/topology.c	2008-06-29 20:42:38.000000000 +0400
@@ -9,7 +9,6 @@
 #include <linux/device.h>
 #include <linux/bootmem.h>
 #include <linux/sched.h>
-#include <linux/kthread.h>
 #include <linux/workqueue.h>
 #include <linux/cpu.h>
 #include <linux/smp.h>
@@ -230,20 +229,9 @@ void arch_update_cpu_topology(void)
 	}
 }
 
-static int topology_kthread(void *data)
-{
-	arch_reinit_sched_domains();
-	return 0;
-}
-
 static void topology_work_fn(struct work_struct *work)
 {
-	/* We can't call arch_reinit_sched_domains() from a multi-threaded
-	 * workqueue context since it may deadlock in case of cpu hotplug.
-	 * So we have to create a kernel thread in order to call
-	 * arch_reinit_sched_domains().
-	 */
-	kthread_run(topology_kthread, NULL, "topology_update");
+	arch_reinit_sched_domains();
 }
 
 void topology_schedule_update(void)

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