Merge tag 'v5.9-rc2' into regulator-5.9

Linux 5.9-rc2

1 files changed, 19 insertions, 0 deletions

diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index a66595ba5543..a2345de90e93 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -99,6 +99,25 @@ void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch)
 EXPORT_SYMBOL(percpu_counter_add_batch);
 
 /*
+ * For percpu_counter with a big batch, the devication of its count could
+ * be big, and there is requirement to reduce the deviation, like when the
+ * counter's batch could be runtime decreased to get a better accuracy,
+ * which can be achieved by running this sync function on each CPU.
+ */
+void percpu_counter_sync(struct percpu_counter *fbc)
+{
+	unsigned long flags;
+	s64 count;
+
+	raw_spin_lock_irqsave(&fbc->lock, flags);
+	count = __this_cpu_read(*fbc->counters);
+	fbc->count += count;
+	__this_cpu_sub(*fbc->counters, count);
+	raw_spin_unlock_irqrestore(&fbc->lock, flags);
+}
+EXPORT_SYMBOL(percpu_counter_sync);
+
+/*
  * Add up all the per-cpu counts, return the result.  This is a more accurate
  * but much slower version of percpu_counter_read_positive()
  */