s390/zcrypt: Replace get_zeroed_page() with kzalloc()

zcrypt_rng_device_add() allocates a buffer for the software random
number generator data cache.

This buffer can be allocated with kmalloc() as there's nothing special
about it to go directly to the page allocator.

kmalloc() provides a better API that does not require ugly casts and
kfree() does not need to know the size of the freed object.

Performance difference between kmalloc() and __get_free_pages() is not
measurable as both allocators take an object/page from a per-CPU list for
fast path allocations.

For the slow path the performance is anyway determined by the amount of
reclaim involved rather than by what allocator is used.

Replace use of get_zeroed_page() with kzalloc() and free_page() with
kfree().

Link: https://lore.kernel.org/all/635405e4-9423-4a25-a6e7-e03c8ea0bcbe@redhat.com
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c
index d6a455df228d07b2b82cf166df2afd9d54c09bf2..f57189c2b839ee4db093d060b93045e4b9f5135f 100644 (file)
--- a/drivers/s390/crypto/zcrypt_api.c
+++ b/drivers/s390/crypto/zcrypt_api.c
@@ -1782,7 +1782,7 @@ int zcrypt_rng_device_add(void)
 
        mutex_lock(&zcrypt_rng_mutex);
        if (zcrypt_rng_device_count == 0) {
-               zcrypt_rng_buffer = (u32 *)get_zeroed_page(GFP_KERNEL);
+               zcrypt_rng_buffer = kzalloc(PAGE_SIZE, GFP_KERNEL);
                if (!zcrypt_rng_buffer) {
                        rc = -ENOMEM;
                        goto out;
@@ -1799,7 +1799,7 @@ int zcrypt_rng_device_add(void)
        return 0;
 
 out_free:
-       free_page((unsigned long)zcrypt_rng_buffer);
+       kfree(zcrypt_rng_buffer);
 out:
        mutex_unlock(&zcrypt_rng_mutex);
        return rc;
@@ -1811,7 +1811,7 @@ void zcrypt_rng_device_remove(void)
        zcrypt_rng_device_count--;
        if (zcrypt_rng_device_count == 0) {
                hwrng_unregister(&zcrypt_rng_dev);
-               free_page((unsigned long)zcrypt_rng_buffer);
+               kfree(zcrypt_rng_buffer);
        }
        mutex_unlock(&zcrypt_rng_mutex);
 }