From e5bb5ade55bfecdc120632e550e3a8ba8dbbc68b Mon Sep 17 00:00:00 2001
From: Thomas Schoebel-Theuer <mars@box>
Date: Sun, 10 Dec 2017 22:43:28 +0100
Subject: [PATCH] logger: replace spinlock by rwsem

---
 kernel/mars_trans_logger.c | 19 +++++++------------
 kernel/mars_trans_logger.h |  2 +-
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/kernel/mars_trans_logger.c b/kernel/mars_trans_logger.c
index 1167438d..0f079a56 100644
--- a/kernel/mars_trans_logger.c
+++ b/kernel/mars_trans_logger.c
@@ -2708,7 +2708,6 @@ void replay_endio(struct generic_callback *cb)
 	struct trans_logger_mref_aspect *mref_a = cb->cb_private;
 	struct trans_logger_brick *brick;
 	bool ok;
-	unsigned long flags;
 
 	_crashme(22, false);
 
@@ -2722,10 +2721,10 @@ void replay_endio(struct generic_callback *cb)
 		MARS_ERR("IO error = %d\n", cb->cb_error);
 	}
 
-	traced_lock(&brick->replay_lock, flags);
+	down_write(&brick->replay_mutex);
 	ok = !list_empty(&mref_a->replay_head);
 	list_del_init(&mref_a->replay_head);
-	traced_unlock(&brick->replay_lock, flags);
+	up_write(&brick->replay_mutex);
 
 	if (likely(ok)) {
 		atomic_dec(&brick->replay_count);
@@ -2745,11 +2744,8 @@ bool _has_conflict(struct trans_logger_brick *brick, struct trans_logger_mref_as
 	struct mref_object *mref = mref_a->object;
 	struct list_head *tmp;
 	bool res = false;
-	unsigned long flags;
 
-	// NOTE: replacing this by rwlock_t will not gain anything, because there exists at most 1 reader at any time
-
-	traced_lock(&brick->replay_lock, flags);
+	down_read(&brick->replay_mutex);
 
 	for (tmp = brick->replay_list.next; tmp != &brick->replay_list; tmp = tmp->next) {
 		struct trans_logger_mref_aspect *tmp_a;
@@ -2763,7 +2759,7 @@ bool _has_conflict(struct trans_logger_brick *brick, struct trans_logger_mref_as
 		}
 	}
 
-	traced_unlock(&brick->replay_lock, flags);
+	up_read(&brick->replay_mutex);
 	return res;
 }
 
@@ -2774,7 +2770,6 @@ void wait_replay(struct trans_logger_brick *brick, struct trans_logger_mref_aspe
 	int conflicts = 0;
 	bool ok = false;
 	bool was_empty;
-	unsigned long flags;
 
 	wait_event_interruptible_timeout(brick->worker_event,
 					 atomic_read(&brick->replay_count) < max
@@ -2785,7 +2780,7 @@ void wait_replay(struct trans_logger_brick *brick, struct trans_logger_mref_aspe
 	if (conflicts)
 		atomic_inc(&brick->total_replay_conflict_count);
 
-	traced_lock(&brick->replay_lock, flags);
+	down_write(&brick->replay_mutex);
 	was_empty = !!list_empty(&mref_a->replay_head);
 	if (likely(was_empty)) {
 		atomic_inc(&brick->replay_count);
@@ -2793,7 +2788,7 @@ void wait_replay(struct trans_logger_brick *brick, struct trans_logger_mref_aspe
 		list_del(&mref_a->replay_head);
 	}
 	list_add(&mref_a->replay_head, &brick->replay_list);
-	traced_unlock(&brick->replay_lock, flags);
+	up_write(&brick->replay_mutex);
 
 	if (unlikely(!was_empty)) {
 		MARS_ERR("replay_head was already used (ok=%d, conflicts=%d, replay_count=%d)\n", ok, conflicts, atomic_read(&brick->replay_count));
@@ -3391,7 +3386,7 @@ int trans_logger_brick_construct(struct trans_logger_brick *brick)
 	}
 
 	atomic_set(&brick->hash_count, 0);
-	spin_lock_init(&brick->replay_lock);
+	init_rwsem(&brick->replay_mutex);
 	INIT_LIST_HEAD(&brick->replay_list);
 	INIT_LIST_HEAD(&brick->group_head);
 	init_waitqueue_head(&brick->worker_event);
diff --git a/kernel/mars_trans_logger.h b/kernel/mars_trans_logger.h
index 723abab0..9b059153 100644
--- a/kernel/mars_trans_logger.h
+++ b/kernel/mars_trans_logger.h
@@ -187,7 +187,7 @@ struct trans_logger_brick {
 	struct trans_logger_hash_anchor **hash_table;
 	struct list_head group_head;
 	loff_t old_margin;
-	spinlock_t replay_lock;
+	struct rw_semaphore replay_mutex;
 	struct list_head replay_list;
 	struct task_struct *thread;
 	wait_queue_head_t worker_event;