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authorHeiko Carstens <heiko.carstens@de.ibm.com>2008-07-14 09:57:28 +0200
committerHeiko Carstens <heiko.carstens@de.ibm.com>2008-07-14 10:02:01 +0200
commitb9732ca1cb2c18129d2f984b8de02db141b7b830 (patch)
tree8614f0d85cace3eaf322ab8b8e429fc1df926927 /drivers
parent0c3252d58c54c87ee0f8f40d840e0146a3b1d5fd (diff)
[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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/s390/char/sclp_config.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/s390/char/sclp_config.c b/drivers/s390/char/sclp_config.c
index ad05a87bc48..7c9b39cee59 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 @@ 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)