metag: smp: enable irqs after set_cpu_online

In secondary_start_kernel() interrupts should be enabled with
local_irq_enable() after the cpu is marked as online with
set_cpu_online(). Otherwise it's possible for a timer interrupt to
trigger a softirq, which if the cpu is marked as offline may have it's
affinity altered.

Reported-by: Kirill Tkhai <tkhai@yandex.ru>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>

1 files changed, 6 insertions, 5 deletions

diff --git a/arch/metag/kernel/smp.c b/arch/metag/kernel/smp.c
index b81351538c48..09979f203a4d 100644
--- a/arch/metag/kernel/smp.c
+++ b/arch/metag/kernel/smp.c
@@ -379,12 +379,7 @@ asmlinkage void secondary_start_kernel(void)
 
         setup_priv();
 
-        /*
-         * Enable local interrupts.
-         */
-        tbi_startup_interrupt(TBID_SIGNUM_TRT);
         notify_cpu_starting(cpu);
-        local_irq_enable();
 
         pr_info("CPU%u (thread %u): Booted secondary processor\n",
                 cpu, cpu_2_hwthread_id[cpu]);
@@ -398,6 +393,12 @@ asmlinkage void secondary_start_kernel(void)
         set_cpu_online(cpu, true);
 
         /*
+         * Enable local interrupts.
+         */
+        tbi_startup_interrupt(TBID_SIGNUM_TRT);
+        local_irq_enable();
+
+        /*
          * OK, it's off to the idle thread for us
          */
         cpu_startup_entry(CPUHP_ONLINE);