[PATCH] x86_64: avoid sending LOCAL_TIMER_VECTOR IPI to itself

Ray Lee reported, that on an UP kernel with "noapic" command line option
set, the box locks hard during boot.

Adding some debug printks revealed, that the last action on the box
before stalling was "Send IPI" - a debug printk which was put into
smp_send_timer_broadcast_ipi().

It seems that send_IPI_mask(mask, LOCAL_TIMER_VECTOR) fails when
"noapic" is set on the command line on an UP kernel.

Aside of that it does not make much sense to trigger an interrupt
instead of calling the function directly on the CPU which gets the
PIT/HPET interrupt in case of broadcasting.

Reported-by: Ray Lee <ray-lk@madrabbit.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by:  Ray Lee <ray-lk@madrabbit.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/x86_64/kernel/apic.c b/arch/x86_64/kernel/apic.c
index 46acf4f2f1ec9e14e5fb2ad7f752213367d2ca10..bd3e45d47c372bd5289b7a9dd1f3099f8267f18e 100644 (file)
--- a/arch/x86_64/kernel/apic.c
+++ b/arch/x86_64/kernel/apic.c
@@ -934,9 +934,17 @@ EXPORT_SYMBOL(switch_APIC_timer_to_ipi);
 
 void smp_send_timer_broadcast_ipi(void)
 {
+       int cpu = smp_processor_id();
        cpumask_t mask;
 
        cpus_and(mask, cpu_online_map, timer_interrupt_broadcast_ipi_mask);
+
+       if (cpu_isset(cpu, mask)) {
+               cpu_clear(cpu, mask);
+               add_pda(apic_timer_irqs, 1);
+               smp_local_timer_interrupt();
+       }
+
        if (!cpus_empty(mask)) {
                send_IPI_mask(mask, LOCAL_TIMER_VECTOR);
        }