s390/ctrlchar: improve handling of magic sysrequests

Extract the sysrq handling from the ctrlchar_handle() into a separate
function that can be directly used by other users.

Introduce a new sysrq_work structure to embed the work_struct and to
specify the magic sysrq function to be invoked.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/char/ctrlchar.c

@@ -14,15 +14,21 @@
 #include "ctrlchar.h"
 
 #ifdef CONFIG_MAGIC_SYSRQ
-static int ctrlchar_sysrq_key;
+static struct sysrq_work ctrlchar_sysrq;
 
 static void
 ctrlchar_handle_sysrq(struct work_struct *work)
 {
-	handle_sysrq(ctrlchar_sysrq_key);
+	struct sysrq_work *sysrq = container_of(work, struct sysrq_work, work);
+
+	handle_sysrq(sysrq->key);
 }
 
-static DECLARE_WORK(ctrlchar_work, ctrlchar_handle_sysrq);
+void schedule_sysrq_work(struct sysrq_work *sw)
+{
+	INIT_WORK(&sw->work, ctrlchar_handle_sysrq);
+	schedule_work(&sw->work);
+}
 #endif
 
 
@@ -51,8 +57,8 @@ ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
 #ifdef CONFIG_MAGIC_SYSRQ
 	/* racy */
 	if (len == 3 && buf[1] == '-') {
-		ctrlchar_sysrq_key = buf[2];
-		schedule_work(&ctrlchar_work);
+		ctrlchar_sysrq.key = buf[2];
+		schedule_sysrq_work(&ctrlchar_sysrq);
 		return CTRLCHAR_SYSRQ;
 	}
 #endif

drivers/s390/char/ctrlchar.h

@@ -7,6 +7,8 @@
  */
 
 #include <linux/tty.h>
+#include <linux/sysrq.h>
+#include <linux/workqueue.h>
 
 extern unsigned int
 ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty);
@@ -17,3 +19,13 @@ ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty);
 #define CTRLCHAR_SYSRQ (3 << 8)
 
 #define CTRLCHAR_MASK (~0xffu)
+
+
+#ifdef CONFIG_MAGIC_SYSRQ
+struct sysrq_work {
+	int key;
+	struct work_struct work;
+};
+
+void schedule_sysrq_work(struct sysrq_work *sw);
+#endif