[PATCH] mm/zswap: careful error path implementation in comp_prepare

[Barry Song <song.bao.hua@xxxxxxxxxxxxx>]

Free the allocated memory and resource while an error occurs.

Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Seth Jennings <sjenning@xxxxxxxxxx>
Cc: Dan Streetman <ddstreet@xxxxxxxx>
Cc: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Barry Song <song.bao.hua@xxxxxxxxxxxxx>
---
 -v1: an incremental patch againest linux-next to fix the issue pointed
      out by Vitaly

 mm/zswap.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/mm/zswap.c b/mm/zswap.c
index 0d914ba6b4a0..c0a85ef46610 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -428,28 +428,31 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
 	struct crypto_acomp *acomp;
 	struct acomp_req *req;
 	struct crypto_acomp_ctx *acomp_ctx;
+	int ret;
 
 	if (WARN_ON(*per_cpu_ptr(pool->acomp_ctx, cpu)))
 		return 0;
 
 	acomp_ctx = kzalloc(sizeof(*acomp_ctx), GFP_KERNEL);
-	if (IS_ERR_OR_NULL(acomp_ctx)) {
-		pr_err("Could not initialize acomp_ctx\n");
+	if (!acomp_ctx) {
+		pr_err("Could not allocate acomp_ctx\n");
 		return -ENOMEM;
 	}
 	acomp = crypto_alloc_acomp(pool->tfm_name, 0, 0);
-	if (IS_ERR_OR_NULL(acomp)) {
+	if (IS_ERR(acomp)) {
 		pr_err("could not alloc crypto acomp %s : %ld\n",
 				pool->tfm_name, PTR_ERR(acomp));
-		return -ENOMEM;
+		ret = PTR_ERR(acomp);
+		goto free_ctx;
 	}
 	acomp_ctx->acomp = acomp;
 
 	req = acomp_request_alloc(acomp_ctx->acomp);
-	if (IS_ERR_OR_NULL(req)) {
-		pr_err("could not alloc crypto acomp %s : %ld\n",
-		       pool->tfm_name, PTR_ERR(acomp));
-		return -ENOMEM;
+	if (!req) {
+		pr_err("could not alloc crypto acomp_request %s\n",
+		       pool->tfm_name);
+		ret = -ENOMEM;
+		goto free_acomp;
 	}
 	acomp_ctx->req = req;
 
@@ -462,6 +465,12 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
 	*per_cpu_ptr(pool->acomp_ctx, cpu) = acomp_ctx;
 
 	return 0;
+
+free_acomp:
+	crypto_free_acomp(acomp_ctx->acomp);
+free_ctx:
+	kfree(acomp_ctx);
+	return ret;
 }
 
 static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
-- 
2.27.0