linux-kernel - [PATCH 4/4] pcpcntr: remove percpu_counter_sum

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Date:   Wed, 15 Mar 2023 19:49:38 +1100
From:   Dave Chinner <david@...morbit.com>
To:     linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org
Cc:     linux-mm@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        yebin10@...wei.com
Subject: [PATCH 4/4] pcpcntr: remove percpu_counter_sum_all()

From: Dave Chinner <dchinner@...hat.com>

percpu_counter_sum_all() is now redundant as the race condition it
was invented to handle is now dealt with by percpu_counter_sum()
directly and all users of percpu_counter_sum_all() have been
removed.

Remove it.

This effectively reverts the changes made in f689054aace2
("percpu_counter: add percpu_counter_sum_all interface") except for
the cpumask iteration that fixes percpu_counter_sum() made earlier
in this series.

Signed-off-by: Dave Chinner <dchinner@...hat.com>
---
 include/linux/percpu_counter.h |  6 -----
 lib/percpu_counter.c           | 40 ++++++++++------------------------
 2 files changed, 11 insertions(+), 35 deletions(-)

diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
index 521a733e21a9..75b73c83bc9d 100644
--- a/include/linux/percpu_counter.h
+++ b/include/linux/percpu_counter.h
@@ -45,7 +45,6 @@ void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
 void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount,
 			      s32 batch);
 s64 __percpu_counter_sum(struct percpu_counter *fbc);
-s64 percpu_counter_sum_all(struct percpu_counter *fbc);
 int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch);
 void percpu_counter_sync(struct percpu_counter *fbc);
 
@@ -196,11 +195,6 @@ static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
 	return percpu_counter_read(fbc);
 }
 
-static inline s64 percpu_counter_sum_all(struct percpu_counter *fbc)
-{
-	return percpu_counter_read(fbc);
-}
-
 static inline bool percpu_counter_initialized(struct percpu_counter *fbc)
 {
 	return true;
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index 0e096311e0c0..5004463c4f9f 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -122,23 +122,6 @@ void percpu_counter_sync(struct percpu_counter *fbc)
 }
 EXPORT_SYMBOL(percpu_counter_sync);
 
-static s64 __percpu_counter_sum_mask(struct percpu_counter *fbc,
-			      const struct cpumask *cpu_mask)
-{
-	s64 ret;
-	int cpu;
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&fbc->lock, flags);
-	ret = fbc->count;
-	for_each_cpu_or(cpu, cpu_online_mask, cpu_mask) {
-		s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
-		ret += *pcount;
-	}
-	raw_spin_unlock_irqrestore(&fbc->lock, flags);
-	return ret;
-}
-
 /*
  * Add up all the per-cpu counts, return the result.  This is a more accurate
  * but much slower version of percpu_counter_read_positive().
@@ -153,22 +136,21 @@ static s64 __percpu_counter_sum_mask(struct percpu_counter *fbc,
  */
 s64 __percpu_counter_sum(struct percpu_counter *fbc)
 {
+	s64 ret;
+	int cpu;
+	unsigned long flags;
 
-	return __percpu_counter_sum_mask(fbc, cpu_dying_mask);
+	raw_spin_lock_irqsave(&fbc->lock, flags);
+	ret = fbc->count;
+	for_each_cpu_or(cpu, cpu_online_mask, cpu_dying_mask) {
+		s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
+		ret += *pcount;
+	}
+	raw_spin_unlock_irqrestore(&fbc->lock, flags);
+	return ret;
 }
 EXPORT_SYMBOL(__percpu_counter_sum);
 
-/*
- * This is slower version of percpu_counter_sum as it traverses all possible
- * cpus. Use this only in the cases where accurate data is needed in the
- * presense of CPUs getting offlined.
- */
-s64 percpu_counter_sum_all(struct percpu_counter *fbc)
-{
-	return __percpu_counter_sum_mask(fbc, cpu_possible_mask);
-}
-EXPORT_SYMBOL(percpu_counter_sum_all);
-
 int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp,
 			  struct lock_class_key *key)
 {
-- 
2.39.2