x86/microcode: fix sleeping function called from invalid context at kernel/mutex.c

Fix the following "sleeping function called from invalid context" bug:

...
__might_sleep
mutex_lock_nested
microcode_update_cpu
mc_sysdev_resume
__sysdev_resume
sysdev_resume
device_power_up
...

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 7 deletions

diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c
index 8db2eb55e9e2..936d8d55f230 100644
--- a/arch/x86/kernel/microcode_core.c
+++ b/arch/x86/kernel/microcode_core.c
@@ -324,10 +324,6 @@ void microcode_update_cpu(int cpu)
         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
         int err = 0;
 
-        /* We should bind the task to the CPU */
-        BUG_ON(raw_smp_processor_id() != cpu);
-
-        mutex_lock(&microcode_mutex);
         /*
          * Check if the system resume is in progress (uci->valid != NULL),
          * otherwise just request a firmware:
@@ -340,11 +336,8 @@ void microcode_update_cpu(int cpu)
                         err = microcode_ops->request_microcode_fw(cpu,
                                         &microcode_pdev->dev);
         }
-
         if (!err)
                 microcode_ops->apply_microcode(cpu);
-
-        mutex_unlock(&microcode_mutex);
 }
 
 static void microcode_init_cpu(int cpu)
@@ -352,7 +345,13 @@ static void microcode_init_cpu(int cpu)
         cpumask_t old = current->cpus_allowed;
 
         set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
+        /* We should bind the task to the CPU */
+        BUG_ON(raw_smp_processor_id() != cpu);
+
+        mutex_lock(&microcode_mutex);
         microcode_update_cpu(cpu);
+        mutex_unlock(&microcode_mutex);
+
         set_cpus_allowed_ptr(current, &old);
 }