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Commit b9732ca1 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

[S390] sclp: fix possible deadlock on cpu rescan. 



smp_rescan_cpus() calls get_online_cpus() from a multithreaded
workqueue context. This may deadlock. This is the same bug as in
arch/s390/kernel/topology.c. This patch can be reverted as soon as
Oleg's patch gets merged.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 0c3252d5

drivers/s390/char/sclp_config.c

+12 −1
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <linux/init.h>

#include <linux/errno.h>

#include <linux/cpu.h>

#include <linux/kthread.h>

#include <linux/sysdev.h>

#include <linux/workqueue.h>

#include <asm/smp.h>
@@ -40,9 +41,19 @@ static void sclp_cpu_capability_notify(struct work_struct *work) 
	put_online_cpus();

}



static void __ref sclp_cpu_change_notify(struct work_struct *work)

static int sclp_cpu_kthread(void *data)

{

	smp_rescan_cpus();

	return 0;

}



static void __ref sclp_cpu_change_notify(struct work_struct *work)

{

	/* Can't call smp_rescan_cpus() from  workqueue context since it may

	 * deadlock in case of cpu hotplug. So we have to create a kernel

	 * thread in order to call it.

	 */

	kthread_run(sclp_cpu_kthread, NULL, "cpu_rescan");

}



static void sclp_conf_receiver_fn(struct evbuf_header *evbuf)