drm/i915: Resolve interaction with drm-fixes tree

[karo-tx-linux.git] / kernel / stop_machine.c

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 32a6c44d8f7837f2f4b5d0fe86ce873cf767dc85..c530bc5be7cfa9e6be364f83848369d204d6d9f8 100644 (file)
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -234,11 +234,13 @@ static void irq_cpu_stop_queue_work(void *arg)
  */
 int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg)
 {
-       int call_cpu;
        struct cpu_stop_done done;
        struct cpu_stop_work work1, work2;
        struct irq_cpu_stop_queue_work_info call_args;
-       struct multi_stop_data msdata = {
+       struct multi_stop_data msdata;
+
+       preempt_disable();
+       msdata = (struct multi_stop_data){
                .fn = fn,
                .data = arg,
                .num_threads = 2,
@@ -261,17 +263,31 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
        cpu_stop_init_done(&done, 2);
        set_state(&msdata, MULTI_STOP_PREPARE);
 
+       /*
+        * If we observe both CPUs active we know _cpu_down() cannot yet have
+        * queued its stop_machine works and therefore ours will get executed
+        * first. Or its not either one of our CPUs that's getting unplugged,
+        * in which case we don't care.
+        *
+        * This relies on the stopper workqueues to be FIFO.
+        */
+       if (!cpu_active(cpu1) || !cpu_active(cpu2)) {
+               preempt_enable();
+               return -ENOENT;
+       }
+
        /*
         * Queuing needs to be done by the lowest numbered CPU, to ensure
         * that works are always queued in the same order on every CPU.
         * This prevents deadlocks.
         */
-       call_cpu = min(cpu1, cpu2);
-
-       smp_call_function_single(call_cpu, &irq_cpu_stop_queue_work,
+       smp_call_function_single(min(cpu1, cpu2),
+                                &irq_cpu_stop_queue_work,
                                 &call_args, 0);
+       preempt_enable();
 
        wait_for_completion(&done.completion);
+
        return done.executed ? done.ret : -ENOENT;
 }