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

[Barry Song]

Free the allocated memory and resource while an error occurs.

Cc: Herbert Xu <herb...@gondor.apana.org.au>
Cc: David S. Miller" <da...@davemloft.net>
Cc: Seth Jennings <sjenn...@redhat.com>
Cc: Dan Streetman <ddstr...@ieee.org>
Cc: Vitaly Wool <vitaly.w...@konsulko.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Barry Song <song.bao....@hisilicon.com>
---
 -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