[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: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/char/sclp_config.c b/drivers/s390/char/sclp_config.c
index ad05a87..7c9b39c 100644
--- a/drivers/s390/char/sclp_config.c
+++ b/drivers/s390/char/sclp_config.c
@@ -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 @@
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)