irqchip/gic: Ensure ordering between read of INTACK and shared data

[cascardo/linux.git] / drivers / irqchip / irq-gic-v3.c

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index f83e5f4..c3870a8 100644 (file)
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -367,6 +367,13 @@ static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs
                        if (static_key_true(&supports_deactivate))
                                gic_write_dir(irqnr);
 #ifdef CONFIG_SMP
+                       /*
+                        * Unlike GICv2, we don't need an smp_rmb() here.
+                        * The control dependency from gic_read_iar to
+                        * the ISB in gic_write_eoir is enough to ensure
+                        * that any shared data read by handle_IPI will
+                        * be read after the ACK.
+                        */
                        handle_IPI(irqnr, regs);
 #else
                        WARN_ONCE(true, "Unexpected SGI received!\n");