IRQCHIP: mips-gic: Don't nest calls to do_IRQ()

The GIC chained handlers use do_IRQ() to call the subhandlers. This
means that irq_enter() calls get nested, which leads to preempt count
looking like we're in nested interrupts, which in turn leads to all
system time being accounted as IRQ time in account_system_time().

Fix it by using generic_handle_irq(). Since these same functions are
used in some systems (if cpu_has_veic) from a low-level vectored
interrupt handler which does not go throught do_IRQ(), we need to do it
conditionally.

Signed-off-by: Rabin Vincent <[e-mail]>
Reviewed-by: Andrew Bresticker <[e-mail]>
Acked-by: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/10545/
Signed-off-by: Ralf Baechle <[e-mail]>

drivers/irqchip/irq-mips-gic.c

···
 				  GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_FDC));
 }
 
-static void gic_handle_shared_int(void)
+static void gic_handle_shared_int(bool chained)
 {
 	unsigned int i, intr, virq;
 	unsigned long *pcpu_mask;
···
 	while (intr != gic_shared_intrs) {
 		virq = irq_linear_revmap(gic_irq_domain,
 					 GIC_SHARED_TO_HWIRQ(intr));
-		do_IRQ(virq);
+		if (chained)
+			generic_handle_irq(virq);
+		else
+			do_IRQ(virq);
 
 		/* go to next pending bit */
 		bitmap_clear(pending, intr, 1);
···
 #endif
 };
 
-static void gic_handle_local_int(void)
+static void gic_handle_local_int(bool chained)
 {
 	unsigned long pending, masked;
 	unsigned int intr, virq;
···
 	while (intr != GIC_NUM_LOCAL_INTRS) {
 		virq = irq_linear_revmap(gic_irq_domain,
 					 GIC_LOCAL_TO_HWIRQ(intr));
-		do_IRQ(virq);
+		if (chained)
+			generic_handle_irq(virq);
+		else
+			do_IRQ(virq);
 
 		/* go to next pending bit */
 		bitmap_clear(&pending, intr, 1);
···
 
 static void __gic_irq_dispatch(void)
 {
-	gic_handle_local_int();
-	gic_handle_shared_int();
+	gic_handle_local_int(false);
+	gic_handle_shared_int(false);
 }
 
 static void gic_irq_dispatch(unsigned int irq, struct irq_desc *desc)
 {
-	__gic_irq_dispatch();
+	gic_handle_local_int(true);
+	gic_handle_shared_int(true);
 }
 
 #ifdef CONFIG_MIPS_GIC_IPI