x86/ioapic: Check attr against the previous setting when programmed more than once

[~andy/linux] / arch / x86 / kernel / apic / io_apic.c

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 260abc2f9eebda97d39b4108524529320e548a7b..e63a5bd2a78f55de2c356b665751558a73bc18da 100644 (file)
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3380,12 +3380,15 @@ int io_apic_setup_irq_pin_once(unsigned int irq, int node,
 {
        unsigned int ioapic_idx = attr->ioapic, pin = attr->ioapic_pin;
        int ret;
+       struct IO_APIC_route_entry orig_entry;
 
        /* Avoid redundant programming */
        if (test_bit(pin, ioapics[ioapic_idx].pin_programmed)) {
-               pr_debug("Pin %d-%d already programmed\n",
-                        mpc_ioapic_id(ioapic_idx), pin);
-               return 0;
+               pr_debug("Pin %d-%d already programmed\n", mpc_ioapic_id(ioapic_idx), pin);
+               orig_entry = ioapic_read_entry(attr->ioapic, pin);
+               if (attr->trigger == orig_entry.trigger && attr->polarity == orig_entry.polarity)
+                       return 0;
+               return -EBUSY;
        }
        ret = io_apic_setup_irq_pin(irq, node, attr);
        if (!ret)