x86, ioapic: Kill static variable nr_irqs_gsi

Static variable nr_irqs_gsi is used to maintain the lowest dynamic
allocatable IRQ number. It may cause trouble when enabling dynamic
IRQ allocation for IOAPIC, so use arch_dynirq_lower_bound() to
avoid directly accessing nr_irqs_gsi and kill nr_irqs_gsi.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1402302011-23642-13-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/apic/io_apic.c

@@ -118,9 +118,6 @@ struct mpc_intsrc mp_irqs[MAX_IRQ_SOURCES];
 /* # of MP IRQ source entries */
 int mp_irq_entries;
 
-/* GSI interrupts */
-static int nr_irqs_gsi = NR_IRQS_LEGACY;
-
 #ifdef CONFIG_EISA
 int mp_bus_id_to_type[MAX_MP_BUSSES];
 #endif
@@ -3326,20 +3323,11 @@ static int __init io_apic_get_redir_entries(int ioapic)
 	return reg_01.bits.entries + 1;
 }
 
-static void __init probe_nr_irqs_gsi(void)
-{
-	int nr;
-
-	nr = gsi_top + NR_IRQS_LEGACY;
-	if (nr > nr_irqs_gsi)
-		nr_irqs_gsi = nr;
-
-	printk(KERN_DEBUG "nr_irqs_gsi: %d\n", nr_irqs_gsi);
-}
-
 unsigned int arch_dynirq_lower_bound(unsigned int from)
 {
-	return from < nr_irqs_gsi ? nr_irqs_gsi : from;
+	unsigned int min = gsi_top + NR_IRQS_LEGACY;
+
+	return from < min ? min : from;
 }
 
 int __init arch_probe_nr_irqs(void)
@@ -3349,12 +3337,12 @@ int __init arch_probe_nr_irqs(void)
 	if (nr_irqs > (NR_VECTORS * nr_cpu_ids))
 		nr_irqs = NR_VECTORS * nr_cpu_ids;
 
-	nr = nr_irqs_gsi + 8 * nr_cpu_ids;
+	nr = (gsi_top + NR_IRQS_LEGACY) + 8 * nr_cpu_ids;
 #if defined(CONFIG_PCI_MSI) || defined(CONFIG_HT_IRQ)
 	/*
 	 * for MSI and HT dyn irq
 	 */
-	nr += nr_irqs_gsi * 16;
+	nr += (gsi_top + NR_IRQS_LEGACY) * 16;
 #endif
 	if (nr < nr_irqs)
 		nr_irqs = nr;
@@ -3627,8 +3615,6 @@ fake_ioapic_page:
 		ioapic_res->end = ioapic_phys + IO_APIC_SLOT_SIZE - 1;
 		ioapic_res++;
 	}
-
-	probe_nr_irqs_gsi();
 }
 
 void __init ioapic_insert_resources(void)