x86: x86 nmi fix 2

From: Don Zickus <dzickus@redhat.com>

Makes the start/stop paths of nmi watchdog more robust to handle the
suspend/resume cases more gracefully.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 arch/i386/kernel/nmi.c   |   19 +++++++++++++++++--
 arch/x86_64/kernel/nmi.c |   19 +++++++++++++++++--
 2 files changed, 34 insertions(+), 4 deletions(-)

Index: linux/arch/i386/kernel/nmi.c
===================================================================
--- linux.orig/arch/i386/kernel/nmi.c
+++ linux/arch/i386/kernel/nmi.c
@@ -630,11 +630,21 @@ static void stop_p4_watchdog(void)
 
 void setup_apic_nmi_watchdog (void *unused)
 {
+	struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
+
 	/* only support LOCAL and IO APICs for now */
 	if ((nmi_watchdog != NMI_LOCAL_APIC) &&
 	    (nmi_watchdog != NMI_IO_APIC))
 	    	return;
 
+	if (wd->enabled == 1)
+		return;
+
+	/* cheap hack to support suspend/resume */
+	/* if cpu0 is not active neither should the other cpus */
+	if ((smp_processor_id() != 0) && (atomic_read(&nmi_active) <= 0))
+		return;
+
 	if (nmi_watchdog == NMI_LOCAL_APIC) {
 		switch (boot_cpu_data.x86_vendor) {
 		case X86_VENDOR_AMD:
@@ -667,17 +677,22 @@ void setup_apic_nmi_watchdog (void *unus
 			return;
 		}
 	}
-	__get_cpu_var(nmi_watchdog_ctlblk.enabled) = 1;
+	wd->enabled = 1;
 	atomic_inc(&nmi_active);
 }
 
 void stop_apic_nmi_watchdog(void *unused)
 {
+	struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
+
 	/* only support LOCAL and IO APICs for now */
 	if ((nmi_watchdog != NMI_LOCAL_APIC) &&
 	    (nmi_watchdog != NMI_IO_APIC))
 	    	return;
 
+	if (wd->enabled == 0)
+		return;
+
 	if (nmi_watchdog == NMI_LOCAL_APIC) {
 		switch (boot_cpu_data.x86_vendor) {
 		case X86_VENDOR_AMD:
@@ -701,7 +716,7 @@ void stop_apic_nmi_watchdog(void *unused
 			return;
 		}
 	}
-	__get_cpu_var(nmi_watchdog_ctlblk.enabled) = 0;
+	wd->enabled = 0;
 	atomic_dec(&nmi_active);
 }
 
Index: linux/arch/x86_64/kernel/nmi.c
===================================================================
--- linux.orig/arch/x86_64/kernel/nmi.c
+++ linux/arch/x86_64/kernel/nmi.c
@@ -565,11 +565,21 @@ static void stop_p4_watchdog(void)
 
 void setup_apic_nmi_watchdog(void *unused)
 {
+	struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
+
 	/* only support LOCAL and IO APICs for now */
 	if ((nmi_watchdog != NMI_LOCAL_APIC) &&
 	    (nmi_watchdog != NMI_IO_APIC))
 	    	return;
 
+	if (wd->enabled == 1)
+		return;
+
+	/* cheap hack to support suspend/resume */
+	/* if cpu0 is not active neither should the other cpus */
+	if ((smp_processor_id() != 0) && (atomic_read(&nmi_active) <= 0))
+		return;
+
 	if (nmi_watchdog == NMI_LOCAL_APIC) {
 		switch (boot_cpu_data.x86_vendor) {
 		case X86_VENDOR_AMD:
@@ -586,17 +596,22 @@ void setup_apic_nmi_watchdog(void *unuse
 			return;
 		}
 	}
-	__get_cpu_var(nmi_watchdog_ctlblk.enabled) = 1;
+	wd->enabled = 1;
 	atomic_inc(&nmi_active);
 }
 
 void stop_apic_nmi_watchdog(void *unused)
 {
+	struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
+
 	/* only support LOCAL and IO APICs for now */
 	if ((nmi_watchdog != NMI_LOCAL_APIC) &&
 	    (nmi_watchdog != NMI_IO_APIC))
 	    	return;
 
+	if (wd->enabled == 0)
+		return;
+
 	if (nmi_watchdog == NMI_LOCAL_APIC) {
 		switch (boot_cpu_data.x86_vendor) {
 		case X86_VENDOR_AMD:
@@ -611,7 +626,7 @@ void stop_apic_nmi_watchdog(void *unused
 			return;
 		}
 	}
-	__get_cpu_var(nmi_watchdog_ctlblk.enabled) = 0;
+	wd->enabled = 0;
 	atomic_dec(&nmi_active);
 }