[PATCH 3.16.y-ckt 154/165] sparc: Touch NMI watchdog when walking cpus and calling printk

Luis Henriques luis.henriques at canonical.com
Wed Mar 25 14:02:07 UTC 2015

3.16.7-ckt9 -stable review patch.  If anyone has any objections, please let me know.


From: David Ahern <david.ahern at oracle.com>

commit 31aaa98c248da766ece922bbbe8cc78cfd0bc920 upstream.

With the increase in number of CPUs calls to functions that dump
output to console (e.g., arch_trigger_all_cpu_backtrace) can take
a long time to complete. If IRQs are disabled eventually the NMI
watchdog kicks in and creates more havoc. Avoid by telling the NMI
watchdog everything is ok.

Signed-off-by: David Ahern <david.ahern at oracle.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 arch/sparc/kernel/process_64.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 0be7bf978cb1..46a59643bb1c 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -287,6 +287,8 @@ void arch_trigger_all_cpu_backtrace(bool include_self)
 			printk("             TPC[%lx] O7[%lx] I7[%lx] RPC[%lx]\n",
 			       gp->tpc, gp->o7, gp->i7, gp->rpc);
+		touch_nmi_watchdog();
 	memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));
@@ -362,6 +364,8 @@ static void pmu_snapshot_all_cpus(void)
 		       (cpu == this_cpu ? '*' : ' '), cpu,
 		       pp->pcr[0], pp->pcr[1], pp->pcr[2], pp->pcr[3],
 		       pp->pic[0], pp->pic[1], pp->pic[2], pp->pic[3]);
+		touch_nmi_watchdog();
 	memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));

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