powerpc: Fix a lazy irq related WARING in arch_local_irq_restore()

The pseries CPU hotplug code uses cede_processor without properly
synchronizing the SW and HW interrupt enable state. This fixes
it using the same helpers that were written for the idle code.

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
=======================
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index a38956269fbf3dd63739d33d7650bf58bf3b4b49..217ca5c75b2007f32615266fb20f36fce359a2cd 100644 (file)
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -127,9 +127,16 @@ static void pseries_mach_cpu_die(void)
                        get_lppaca()->donate_dedicated_cpu = 1;
 
                while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
+                       while (!prep_irq_for_idle()) {
+                               local_irq_enable();
+                               local_irq_disable();
+                       }
+
                        extended_cede_processor(cede_latency_hint);
                }
 
+               local_irq_disable();
+
                if (!get_lppaca()->shared_proc)
                        get_lppaca()->donate_dedicated_cpu = 0;
                get_lppaca()->idle = 0;
@@ -137,6 +144,7 @@ static void pseries_mach_cpu_die(void)
                if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) {
                        unregister_slb_shadow(hwcpu);
 
+                       hard_irq_disable();
                        /*
                         * Call to start_secondary_resume() will not return.
                         * Kernel stack will be reset and start_secondary()

diff --git a/arch/powerpc/platforms/pseries/plpar_wrappers.h b/arch/powerpc/platforms/pseries/plpar_wrappers.h
index e6cc34a670530ec4f0b2e3375c9791cac34230d1..b93384929c4cbc2f7274820dbfaf549aa9e274fd 100644 (file)
--- a/arch/powerpc/platforms/pseries/plpar_wrappers.h
+++ b/arch/powerpc/platforms/pseries/plpar_wrappers.h
@@ -2,6 +2,7 @@
 #define _PSERIES_PLPAR_WRAPPERS_H
 
 #include <linux/string.h>
+#include <linux/irqflags.h>
 
 #include <asm/hvcall.h>
 #include <asm/paca.h>
@@ -41,7 +42,14 @@ static inline long extended_cede_processor(unsigned long latency_hint)
        u8 old_latency_hint = get_cede_latency_hint();
 
        set_cede_latency_hint(latency_hint);
+
        rc = cede_processor();
+#ifdef CONFIG_TRACE_IRQFLAGS
+               /* Ensure that H_CEDE returns with IRQs on */
+               if (WARN_ON(!(mfmsr() & MSR_EE)))
+                       __hard_irq_enable();
+#endif
+
        set_cede_latency_hint(old_latency_hint);
 
        return rc;