Merge branch 'tegra/dt64' into arm/fixes

[linux-2.6-microblaze.git] / arch / powerpc / platforms / pseries / mobility.c

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index ea4d6a6..e83e089 100644 (file)
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -452,12 +452,28 @@ static int do_suspend(void)
        return ret;
 }
 
+/**
+ * struct pseries_suspend_info - State shared between CPUs for join/suspend.
+ * @counter: Threads are to increment this upon resuming from suspend
+ *           or if an error is received from H_JOIN. The thread which performs
+ *           the first increment (i.e. sets it to 1) is responsible for
+ *           waking the other threads.
+ * @done: False if join/suspend is in progress. True if the operation is
+ *        complete (successful or not).
+ */
+struct pseries_suspend_info {
+       atomic_t counter;
+       bool done;
+};
+
 static int do_join(void *arg)
 {
-       atomic_t *counter = arg;
+       struct pseries_suspend_info *info = arg;
+       atomic_t *counter = &info->counter;
        long hvrc;
        int ret;
 
+retry:
        /* Must ensure MSR.EE off for H_JOIN. */
        hard_irq_disable();
        hvrc = plpar_hcall_norets(H_JOIN);
@@ -473,8 +489,20 @@ static int do_join(void *arg)
        case H_SUCCESS:
                /*
                 * The suspend is complete and this cpu has received a
-                * prod.
+                * prod, or we've received a stray prod from unrelated
+                * code (e.g. paravirt spinlocks) and we need to join
+                * again.
+                *
+                * This barrier orders the return from H_JOIN above vs
+                * the load of info->done. It pairs with the barrier
+                * in the wakeup/prod path below.
                 */
+               smp_mb();
+               if (READ_ONCE(info->done) == false) {
+                       pr_info_ratelimited("premature return from H_JOIN on CPU %i, retrying",
+                                           smp_processor_id());
+                       goto retry;
+               }
                ret = 0;
                break;
        case H_BAD_MODE:
@@ -488,6 +516,13 @@ static int do_join(void *arg)
 
        if (atomic_inc_return(counter) == 1) {
                pr_info("CPU %u waking all threads\n", smp_processor_id());
+               WRITE_ONCE(info->done, true);
+               /*
+                * This barrier orders the store to info->done vs subsequent
+                * H_PRODs to wake the other CPUs. It pairs with the barrier
+                * in the H_SUCCESS case above.
+                */
+               smp_mb();
                prod_others();
        }
        /*
@@ -535,11 +570,16 @@ static int pseries_suspend(u64 handle)
        int ret;
 
        while (true) {
-               atomic_t counter = ATOMIC_INIT(0);
+               struct pseries_suspend_info info;
                unsigned long vasi_state;
                int vasi_err;
 
-               ret = stop_machine(do_join, &counter, cpu_online_mask);
+               info = (struct pseries_suspend_info) {
+                       .counter = ATOMIC_INIT(0),
+                       .done = false,
+               };
+
+               ret = stop_machine(do_join, &info, cpu_online_mask);
                if (ret == 0)
                        break;
                /*