sparc64: On non-Niagara, need to touch NMI watchdog in NOHZ mode.

When we're idling in NOHZ mode, timer interrupts are not running.

Evidence of processing timer interrupts is what the NMI watchdog
uses to determine if the CPU is stuck.

On Niagara, we'll yield the cpu.  This will make the cpu, at
worst, hang out in the hypervisor until an interrupt arrives.
This will prevent the NMI watchdog timer from firing.

However on non-Niagara we just loop executing instructions
which will cause the NMI watchdog to keep firing.  It won't
see timer interrupts happening so it will think the cpu is
stuck.

Fix this by touching the NMI watchdog in the cpu idle loop
on non-Niagara machines.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index cc8b5604442cc0968c6ff96311e9c998e45df86f..a73954b87f0a511ad7431b4b33f82216f22e2b7c 100644 (file)
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -29,6 +29,7 @@
 #include <linux/cpu.h>
 #include <linux/elfcore.h>
 #include <linux/sysrq.h>
+#include <linux/nmi.h>
 
 #include <asm/uaccess.h>
 #include <asm/system.h>
@@ -52,8 +53,10 @@
 
 static void sparc64_yield(int cpu)
 {
-       if (tlb_type != hypervisor)
+       if (tlb_type != hypervisor) {
+               touch_nmi_watchdog();
                return;
+       }
 
        clear_thread_flag(TIF_POLLING_NRFLAG);
        smp_mb__after_clear_bit();