ACPI: avoid irqrouter_resume might_sleep oops on resume from S4

__might_sleep+0x8e/0x93
acpi_os_wait_semaphore+0x50/0xa3
acpi_ut_acquire_mutex+0x28/0x6a
acpi_ns_get_node+0x46/0x88
acpi_ns_evaluate+0x2d/0xfc
acpi_rs_set_srs_method_data+0xc5/0xe1
acpi_set_current_resources+0x31/0x3f
acpi_pci_link_set+0xfc/0x1a5
irqrouter_resume+0x48/0x5f

and

__might_sleep+0x8e/0x93
kmem_cache_alloc+0x2a/0x8f
acpi_evaluate_integer+0x32/0x96
acpi_bus_get_status+0x30/0x84
acpi_pci_link_set+0x12a/0x1a5
irqrouter_resume+0x48/0x5f

http://bugzilla.kernel.org/show_bug.cgi?id=6810

Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index b7d1514cd199..507f051d1cef 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -746,6 +746,16 @@ acpi_status acpi_os_wait_semaphore(acpi_handle handle, u32 units, u16 timeout)
         ACPI_DEBUG_PRINT((ACPI_DB_MUTEX, "Waiting for semaphore[%p|%d|%d]\n",
                           handle, units, timeout));
 
+        /*
+         * This can be called during resume with interrupts off.
+         * Like boot-time, we should be single threaded and will
+         * always get the lock if we try -- timeout or not.
+         * If this doesn't succeed, then we will oops courtesy of
+         * might_sleep() in down().
+         */
+        if (!down_trylock(sem))
+                return AE_OK;
+
         switch (timeout) {
                 /*
                  * No Wait: