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>
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(-)

diff -puN arch/i386/kernel/nmi.c~x86-nmi-fix-2 arch/i386/kernel/nmi.c
--- devel/arch/i386/kernel/nmi.c~x86-nmi-fix-2	2006-06-09 00:42:52.000000000 -0700
+++ devel-akpm/arch/i386/kernel/nmi.c	2006-06-09 00:42:52.000000000 -0700
@@ -744,11 +744,21 @@ static void stop_intel_arch_watchdog(voi
 
 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:
@@ -786,17 +796,22 @@ 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:
@@ -824,7 +839,7 @@ void stop_apic_nmi_watchdog(void *unused
 			return;
 		}
 	}
-	__get_cpu_var(nmi_watchdog_ctlblk.enabled) = 0;
+	wd->enabled = 0;
 	atomic_dec(&nmi_active);
 }
 
diff -puN arch/x86_64/kernel/nmi.c~x86-nmi-fix-2 arch/x86_64/kernel/nmi.c
--- devel/arch/x86_64/kernel/nmi.c~x86-nmi-fix-2	2006-06-09 00:42:52.000000000 -0700
+++ devel-akpm/arch/x86_64/kernel/nmi.c	2006-06-09 00:42:52.000000000 -0700
@@ -671,11 +671,21 @@ static void stop_intel_arch_watchdog(voi
 
 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:
@@ -697,17 +707,22 @@ 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:
@@ -726,7 +741,7 @@ void stop_apic_nmi_watchdog(void *unused
 			return;
 		}
 	}
-	__get_cpu_var(nmi_watchdog_ctlblk.enabled) = 0;
+	wd->enabled = 0;
 	atomic_dec(&nmi_active);
 }
 
_