[PATCH 3/5] s390/vmlogrdr: Replace get_zeroed_page() with kzalloc()

["Mike Rapoport (Microsoft)" <rppt@kernel.org>]

vmlogrdr_init() allocates the buffers used to receive z/VM system
service records via IUCV.

These buffers can be allocated with kmalloc() as there's nothing special
about them 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
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
 drivers/s390/char/vmlogrdr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/char/vmlogrdr.c b/drivers/s390/char/vmlogrdr.c
index 005735a899203..229a0f71dc453 100644
--- a/drivers/s390/char/vmlogrdr.c
+++ b/drivers/s390/char/vmlogrdr.c
@@ -793,7 +793,7 @@ static void vmlogrdr_cleanup(void)
 	}
 	for (i=0; i < MAXMINOR; ++i ) {
 		vmlogrdr_unregister_device(&sys_ser[i]);
-		free_page((unsigned long)sys_ser[i].buffer);
+		kfree(sys_ser[i].buffer);
 	}
 	vmlogrdr_unregister_driver();
 	if (vmlogrdr_major) {
@@ -826,7 +826,7 @@ static int __init vmlogrdr_init(void)
 		goto cleanup;
 
 	for (i=0; i < MAXMINOR; ++i ) {
-		sys_ser[i].buffer = (char *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+		sys_ser[i].buffer = kzalloc(PAGE_SIZE, GFP_KERNEL | GFP_DMA);
 		if (!sys_ser[i].buffer) {
 			rc = -ENOMEM;
 			break;

-- 
2.53.0