path: root/arch
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authorThomas Gleixner <tglx@linutronix.de>2017-10-03 16:39:02 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-10-04 10:53:54 +0200
commit34ddaa3e5c0096fef52485186c7eb6cf56ddc686 (patch)
tree3d98dfe007218f46a0b9b287fb2fe58b4797a9d5 /arch
parentwatchdog/core, powerpc: Lock cpus across reconfiguration (diff)
powerpc/watchdog: Make use of watchdog_nmi_probe()
The rework of the core hotplug code triggers the WARN_ON in start_wd_cpu() on powerpc because it is called multiple times for the boot CPU. The first call is via: start_wd_on_cpu+0x80/0x2f0 watchdog_nmi_reconfigure+0x124/0x170 softlockup_reconfigure_threads+0x110/0x130 lockup_detector_init+0xbc/0xe0 kernel_init_freeable+0x18c/0x37c kernel_init+0x2c/0x160 ret_from_kernel_thread+0x5c/0xbc And then again via the CPU hotplug registration: start_wd_on_cpu+0x80/0x2f0 cpuhp_invoke_callback+0x194/0x620 cpuhp_thread_fun+0x7c/0x1b0 smpboot_thread_fn+0x290/0x2a0 kthread+0x168/0x1b0 ret_from_kernel_thread+0x5c/0xbc This can be avoided by setting up the cpu hotplug state with nocalls and move the initialization to the watchdog_nmi_probe() function. That initializes the hotplug callbacks without invoking the callback and the following core initialization function then configures the watchdog for the online CPUs (in this case CPU0) via softlockup_reconfigure_threads(). Reported-and-tested-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: linuxppc-dev@lists.ozlabs.org
Diffstat (limited to 'arch')
1 files changed, 8 insertions, 9 deletions
diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index f9b4c6352d24..c702a8981452 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -373,22 +373,21 @@ void watchdog_nmi_start(void)
- * This runs after lockup_detector_init() which sets up watchdog_cpumask.
+ * Invoked from core watchdog init.
-static int __init powerpc_watchdog_init(void)
+int __init watchdog_nmi_probe(void)
int err;
- watchdog_calc_timeouts();
- err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "powerpc/watchdog:online",
- start_wd_on_cpu, stop_wd_on_cpu);
- if (err < 0)
+ err = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
+ "powerpc/watchdog:online",
+ start_wd_on_cpu, stop_wd_on_cpu);
+ if (err < 0) {
pr_warn("Watchdog could not be initialized");
+ return err;
+ }
return 0;
static void handle_backtrace_ipi(struct pt_regs *regs)