[PATCH] ACPI: s2idle: Don't ignore error when enabling wakeup IRQ

[Simon Gaiser <simon@invisiblethingslab.com>]

enable_irq_wake() can fail. Previously acpi_s2idle_prepare() silently
ignored it's return code, potentially leaving a system that never wakes
up.

Discovered when trying to go into s2idle under Xen. This leads to a
system that can't be woken, since xen-pirq currently doesn't support
setting wakeup IRQs. Real s2idle support for Xen is another topic, but
now at least the user gets an error and the system doesn't needs an hard
reset.

Signed-off-by: Simon Gaiser <simon@invisiblethingslab.com>
---

Note that I'm unfamiliar with the code so when reviewing please
carefully check if ignoring the error was indeed unintended.

If there are indeed cases where the error should be ignored I would
submit a patch that at least logs the error, although the error message
would be hard to see with broken wakeup.

 drivers/acpi/sleep.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 4ca667251272..c69dd3731126 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -714,7 +714,15 @@ int acpi_s2idle_begin(void)
 int acpi_s2idle_prepare(void)
 {
 	if (acpi_sci_irq_valid()) {
-		enable_irq_wake(acpi_sci_irq);
+		int error;
+
+		error = enable_irq_wake(acpi_sci_irq);
+		if (error) {
+			pr_err("Failed to enable wakeup from IRQ %d: %d\n",
+			       acpi_sci_irq,
+			       error);
+			return error;
+		}
 		acpi_ec_set_gpe_wake_mask(ACPI_GPE_ENABLE);
 	}
 
-- 
2.39.2