s390/smp: Avoid busy loop after halt and "begin" on z/VM

Currently the smp_stop_cpu() function for SMP kernels enters a busy
loop when "begin" is entered on the z/VM console after Linux is halted.
To avoid this behavior, use the non-SMP variant of smp_stop_cpu()
which stops the CPU again after "begin" is entered. As a side
effect we now have consistent behavior for SMP and non-SMP Linux.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/include/asm/smp.h b/arch/s390/include/asm/smp.h
index 21703f85b48d8d0c1c1c229791a2cfe1dc9294d8..4f1307962a95a307d6dff37acf897abba8f7595d 100644 (file)
--- a/arch/s390/include/asm/smp.h
+++ b/arch/s390/include/asm/smp.h
@@ -30,7 +30,6 @@ extern int smp_store_status(int cpu);
 extern int smp_vcpu_scheduled(int cpu);
 extern void smp_yield_cpu(int cpu);
 extern void smp_yield(void);
-extern void smp_stop_cpu(void);
 extern void smp_cpu_set_polarization(int cpu, int val);
 extern int smp_cpu_get_polarization(int cpu);
 extern void smp_fill_possible_mask(void);
@@ -54,6 +53,8 @@ static inline void smp_yield_cpu(int cpu) { }
 static inline void smp_yield(void) { }
 static inline void smp_fill_possible_mask(void) { }
 
+#endif /* CONFIG_SMP */
+
 static inline void smp_stop_cpu(void)
 {
        u16 pcpu = stap();
@@ -64,8 +65,6 @@ static inline void smp_stop_cpu(void)
        }
 }
 
-#endif /* CONFIG_SMP */
-
 #ifdef CONFIG_HOTPLUG_CPU
 extern int smp_rescan_cpus(void);
 extern void __noreturn cpu_die(void);

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 4b8b7f6284d1ebab928332988e55acf7fcc64160..243c7e51260055c3de2a57e2852ed82de075f18f 100644 (file)
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -404,15 +404,6 @@ void smp_send_stop(void)
        }
 }
 
-/*
- * Stop the current cpu.
- */
-void smp_stop_cpu(void)
-{
-       pcpu_sigp_retry(pcpu_devices + smp_processor_id(), SIGP_STOP, 0);
-       for (;;) ;
-}
-
 /*
  * This is the main routine where commands issued by other
  * cpus are handled.