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 <>
Signed-off-by: default avatarMartin Schwidefsky <>
parent 0c3252d5
...@@ -8,6 +8,7 @@ ...@@ -8,6 +8,7 @@
#include <linux/init.h> #include <linux/init.h>
#include <linux/errno.h> #include <linux/errno.h>
#include <linux/cpu.h> #include <linux/cpu.h>
#include <linux/kthread.h>
#include <linux/sysdev.h> #include <linux/sysdev.h>
#include <linux/workqueue.h> #include <linux/workqueue.h>
#include <asm/smp.h> #include <asm/smp.h>
...@@ -40,9 +41,19 @@ static void sclp_cpu_capability_notify(struct work_struct *work) ...@@ -40,9 +41,19 @@ static void sclp_cpu_capability_notify(struct work_struct *work)
put_online_cpus(); put_online_cpus();
} }
static void __ref sclp_cpu_change_notify(struct work_struct *work) static int sclp_cpu_kthread(void *data)
{ {
smp_rescan_cpus(); 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) static void sclp_conf_receiver_fn(struct evbuf_header *evbuf)
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