[PATCH v07 7/9] powerpc/rtas: Allow disabling rtas_event_scan

[Michael Bringmann <mwb@linux.vnet.ibm.com>]

powerpc/rtas: Provide mechanism by which the rtas_event_scan can
be disabled/re-enabled by other portions of the powerpc code.
Among other things, this simplifies the usage of locking mechanisms
for shared kernel resources.

Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/rtas.h |    4 ++++
 arch/powerpc/kernel/rtasd.c     |   14 ++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 4f601c7..4ab605a 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -386,8 +386,12 @@ extern int early_init_dt_scan_rtas(unsigned long node,
 
 #ifdef CONFIG_PPC_RTAS_DAEMON
 extern void rtas_cancel_event_scan(void);
+extern void rtas_event_scan_disable(void);
+extern void rtas_event_scan_enable(void);
 #else
 static inline void rtas_cancel_event_scan(void) { }
+static inline void rtas_event_scan_disable(void) { }
+static inline void rtas_event_scan_enable(void) { }
 #endif
 
 /* Error types logged.  */
diff --git a/arch/powerpc/kernel/rtasd.c b/arch/powerpc/kernel/rtasd.c
index 44d66c33d..af69e44 100644
--- a/arch/powerpc/kernel/rtasd.c
+++ b/arch/powerpc/kernel/rtasd.c
@@ -455,11 +455,25 @@ static void do_event_scan(void)
  */
 static unsigned long event_scan_delay = 1*HZ;
 static int first_pass = 1;
+static int res_enable = 1;
+
+void rtas_event_scan_disable(void)
+{
+	res_enable = 0;
+}
+
+void rtas_event_scan_enable(void)
+{
+	res_enable = 1;
+}
 
 static void rtas_event_scan(struct work_struct *w)
 {
 	unsigned int cpu;
 
+	if (!res_enable)
+		return;
+
 	do_event_scan();
 
 	get_online_cpus();