softlockup: allow panic on lockup

allow users to configure the softlockup detector to generate a panic
instead of a warning message.

high-availability systems might opt for this strict method (combined
with panic_timeout= boot option/sysctl), instead of generating
softlockup warnings ad infinitum.

also, automated tests work better if the system reboots reliably (into
a safe kernel) in case of a lockup.

The full spectrum of configurability is supported: boot option, sysctl
option and Kconfig option.

it's default-disabled.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 11 insertions, 0 deletions

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 29116652dca8..2d3b388c402d 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -729,6 +729,17 @@ static struct ctl_table kern_table[] = {
 #ifdef CONFIG_DETECT_SOFTLOCKUP
         {
                 .ctl_name       = CTL_UNNUMBERED,
+                .procname       = "softlockup_panic",
+                .data           = &softlockup_panic,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = &proc_doulongvec_minmax,
+                .strategy       = &sysctl_intvec,
+                .extra1         = &zero,
+                .extra2         = &one,
+        },
+        {
+                .ctl_name       = CTL_UNNUMBERED,
                 .procname       = "softlockup_thresh",
                 .data           = &softlockup_thresh,
                 .maxlen         = sizeof(unsigned long),