powerpc/watchdog: add support for hardlockup_sys_info sysctl

Commit a9af76a78760 ("watchdog: add sys_info sysctls to dump sys info on
system lockup") adds 'hardlock_sys_info' systcl knob for general kernel
watchdog to control what kinds of system debug info to be dumped on
hardlockup.

Add similar support in powerpc watchdog code to make the sysctl knob more
general, which also fixes a compiling warning in general watchdog code
reported by 0day bot.

Link: https://lkml.kernel.org/r/20251231080309.39642-1-feng.tang@linux.alibaba.com
Fixes: a9af76a78760 ("watchdog: add sys_info sysctls to dump sys info on system lockup")
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512030920.NFKtekA7-lkp@intel.com/
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index 2429cb1..764001d 100644 (file)
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -26,6 +26,7 @@
 #include <linux/delay.h>
 #include <linux/processor.h>
 #include <linux/smp.h>
+#include <linux/sys_info.h>
 
 #include <asm/interrupt.h>
 #include <asm/paca.h>
@@ -235,7 +236,11 @@ static void watchdog_smp_panic(int cpu)
        pr_emerg("CPU %d TB:%lld, last SMP heartbeat TB:%lld (%lldms ago)\n",
                 cpu, tb, last_reset, tb_to_ns(tb - last_reset) / 1000000);
 
-       if (!sysctl_hardlockup_all_cpu_backtrace) {
+       if (sysctl_hardlockup_all_cpu_backtrace ||
+           (hardlockup_si_mask & SYS_INFO_ALL_BT)) {
+               trigger_allbutcpu_cpu_backtrace(cpu);
+               cpumask_clear(&wd_smp_cpus_ipi);
+       } else {
                /*
                 * Try to trigger the stuck CPUs, unless we are going to
                 * get a backtrace on all of them anyway.
@@ -244,11 +249,9 @@ static void watchdog_smp_panic(int cpu)
                        smp_send_nmi_ipi(c, wd_lockup_ipi, 1000000);
                        __cpumask_clear_cpu(c, &wd_smp_cpus_ipi);
                }
-       } else {
-               trigger_allbutcpu_cpu_backtrace(cpu);
-               cpumask_clear(&wd_smp_cpus_ipi);
        }
 
+       sys_info(hardlockup_si_mask & ~SYS_INFO_ALL_BT);
        if (hardlockup_panic)
                nmi_panic(NULL, "Hard LOCKUP");
 
@@ -415,9 +418,11 @@ DEFINE_INTERRUPT_HANDLER_NMI(soft_nmi_interrupt)
 
                xchg(&__wd_nmi_output, 1); // see wd_lockup_ipi
 
-               if (sysctl_hardlockup_all_cpu_backtrace)
+               if (sysctl_hardlockup_all_cpu_backtrace ||
+                   (hardlockup_si_mask & SYS_INFO_ALL_BT))
                        trigger_allbutcpu_cpu_backtrace(cpu);
 
+               sys_info(hardlockup_si_mask & ~SYS_INFO_ALL_BT);
                if (hardlockup_panic)
                        nmi_panic(regs, "Hard LOCKUP");
 

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index cf3c6ab..207156f 100644 (file)
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -83,6 +83,7 @@ static inline void reset_hung_task_detector(void) { }
 #if defined(CONFIG_HARDLOCKUP_DETECTOR)
 extern void hardlockup_detector_disable(void);
 extern unsigned int hardlockup_panic;
+extern unsigned long hardlockup_si_mask;
 #else
 static inline void hardlockup_detector_disable(void) {}
 #endif

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 0685e3a..366122f 100644 (file)
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -71,7 +71,7 @@ unsigned int __read_mostly hardlockup_panic =
  * hard lockup is detected, it could be task, memory, lock etc.
  * Refer include/linux/sys_info.h for detailed bit definition.
  */
-static unsigned long hardlockup_si_mask;
+unsigned long hardlockup_si_mask;
 
 #ifdef CONFIG_SYSFS