There are presently redundant checks on the per-CPU acomp_ctx and it's "req" member in zswap_cpu_comp_dead(): redundant because they are inconsistent with zswap_pool_create() handling of failure in allocating the acomp_ctx, and with the expected NULL return value from the acomp_request_alloc() API when it fails to allocate an acomp_req. Fix these by converting to them to be NULL checks. Add comments in zswap_cpu_comp_prepare() clarifying the expected return values of the crypto_alloc_acomp_node() and acomp_request_alloc() API. Suggested-by: Yosry Ahmed Signed-off-by: Kanchana P. Sridhar --- mm/zswap.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index bdd24430f6ff..8ac38f1d0469 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -749,6 +749,10 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) goto fail; } + /* + * In case of an error, crypto_alloc_acomp_node() returns an + * error pointer, never NULL. + */ acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu)); if (IS_ERR(acomp)) { pr_err("could not alloc crypto acomp %s : %pe\n", @@ -757,6 +761,7 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) goto fail; } + /* acomp_request_alloc() returns NULL in case of an error. */ req = acomp_request_alloc(acomp); if (!req) { pr_err("could not alloc crypto acomp_request %s\n", @@ -802,7 +807,7 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) struct crypto_acomp *acomp; u8 *buffer; - if (IS_ERR_OR_NULL(acomp_ctx)) + if (!acomp_ctx) return 0; mutex_lock(&acomp_ctx->mutex); @@ -817,8 +822,11 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) /* * Do the actual freeing after releasing the mutex to avoid subtle * locking dependencies causing deadlocks. + * + * If there was an error in allocating @acomp_ctx->req, it + * would be set to NULL. */ - if (!IS_ERR_OR_NULL(req)) + if (req) acomp_request_free(req); if (!IS_ERR_OR_NULL(acomp)) crypto_free_acomp(acomp); -- 2.39.5