Sep 13 2015

dm: drop NULL test before kmem_cache_destroy() and mempool_destroy() 

Author: Julia Lawall <Julia.Lawall@lip6.fr>

Remove DM's unneeded NULL tests before calling these destroy functions,
now that they check for NULL, thanks to these v4.3 commits:
3942d2991 ("mm/slab_common: allow NULL cache pointer in kmem_cache_destroy()")
4e3ca3e03 ("mm/mempool: allow NULL `pool' pointer in mempool_destroy()")

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// 
@@ expression x; @@
-if (x != NULL)
  \(kmem_cache_destroy\|mempool_destroy\|dma_pool_destroy\)(x);
// 

Signed-off-by: Julia Lawall 
Signed-off-by: Mike Snitzer 

---
 drivers/md/dm-bufio.c              |  8 ++------
 drivers/md/dm-cache-target.c       |  3 +--
 drivers/md/dm-crypt.c              |  6 ++----
 drivers/md/dm-io.c                 |  3 +--
 drivers/md/dm-log-userspace-base.c |  3 +--
 drivers/md/dm-region-hash.c        |  4 +---
 drivers/md/dm.c                    | 13 ++++---------
 7 files changed, 12 insertions(+), 28 deletions(-)
 
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 83cc52e..e1547d0 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -1861,12 +1861,8 @@ static void __exit dm_bufio_exit(void)
 	cancel_delayed_work_sync(&dm_bufio_work);
 	destroy_workqueue(dm_bufio_wq);
 
-	for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++) {
-		struct kmem_cache *kc = dm_bufio_caches[i];
-
-		if (kc)
-			kmem_cache_destroy(kc);
-	}
+	for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++)
+		kmem_cache_destroy(dm_bufio_caches[i]);
 
 	for (i = 0; i < ARRAY_SIZE(dm_bufio_cache_names); i++)
 		kfree(dm_bufio_cache_names[i]);
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index dd90d12..2fd4c82 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -2309,8 +2309,7 @@ static void destroy(struct cache *cache)
 {
 	unsigned i;
 
-	if (cache->migration_pool)
-		mempool_destroy(cache->migration_pool);
+	mempool_destroy(cache->migration_pool);
 
 	if (cache->all_io_ds)
 		dm_deferred_set_destroy(cache->all_io_ds);
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 4b3b6f8..3729b39 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1544,10 +1544,8 @@ static void crypt_dtr(struct dm_target *ti)
 	if (cc->bs)
 		bioset_free(cc->bs);
 
-	if (cc->page_pool)
-		mempool_destroy(cc->page_pool);
-	if (cc->req_pool)
-		mempool_destroy(cc->req_pool);
+	mempool_destroy(cc->page_pool);
+	mempool_destroy(cc->req_pool);
 
 	if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 		cc->iv_gen_ops->dtr(cc);
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 6f8e83b2..81c5e1a 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -65,8 +65,7 @@ struct dm_io_client *dm_io_client_create(void)
 	return client;
 
    bad:
-	if (client->pool)
-		mempool_destroy(client->pool);
+	mempool_destroy(client->pool);
 	kfree(client);
 	return ERR_PTR(-ENOMEM);
 }
diff --git a/drivers/md/dm-log-userspace-base.c b/drivers/md/dm-log-userspace-base.c
index 058256d..53b7b06d 100644
--- a/drivers/md/dm-log-userspace-base.c
+++ b/drivers/md/dm-log-userspace-base.c
@@ -313,8 +313,7 @@ static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
 out:
 	kfree(devices_rdata);
 	if (r) {
-		if (lc->flush_entry_pool)
-			mempool_destroy(lc->flush_entry_pool);
+		mempool_destroy(lc->flush_entry_pool);
 		kfree(lc);
 		kfree(ctr_str);
 	} else {
diff --git a/drivers/md/dm-region-hash.c b/drivers/md/dm-region-hash.c
index b929fd5..f3d608b 100644
--- a/drivers/md/dm-region-hash.c
+++ b/drivers/md/dm-region-hash.c
@@ -249,9 +249,7 @@ void dm_region_hash_destroy(struct dm_region_hash *rh)
 	if (rh->log)
 		dm_dirty_log_destroy(rh->log);
 
-	if (rh->region_pool)
-		mempool_destroy(rh->region_pool);
-
+	mempool_destroy(rh->region_pool);
 	vfree(rh->buckets);
 	kfree(rh);
 }
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index c31ca8b..9555843 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2254,10 +2254,8 @@ static void cleanup_mapped_device(struct mapped_device *md)
 		destroy_workqueue(md->wq);
 	if (md->kworker_task)
 		kthread_stop(md->kworker_task);
-	if (md->io_pool)
-		mempool_destroy(md->io_pool);
-	if (md->rq_pool)
-		mempool_destroy(md->rq_pool);
+	mempool_destroy(md->io_pool);
+	mempool_destroy(md->rq_pool);
 	if (md->bs)
 		bioset_free(md->bs);
 
@@ -3542,11 +3540,8 @@ void dm_free_md_mempools(struct dm_md_mempools *pools)
 	if (!pools)
 		return;
 
-	if (pools->io_pool)
-		mempool_destroy(pools->io_pool);
-
-	if (pools->rq_pool)
-		mempool_destroy(pools->rq_pool);
+	mempool_destroy(pools->io_pool);
+	mempool_destroy(pools->rq_pool);
 
 	if (pools->bs)
 		bioset_free(pools->bs);

qlambert