[PATCH 11/14] s390/sclp_cpi: Replace get_zeroed_page() with kzalloc()

[Mike Rapoport (Microsoft)]

cpi_prepare_req() allocates the SCCB used to send the control program
identification to the SCLP.

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@xxxxxxxxxx
Signed-off-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
---
 drivers/s390/char/sclp_cpi_sys.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/char/sclp_cpi_sys.c b/drivers/s390/char/sclp_cpi_sys.c
index b80f73fa1e01b..8bca2cdb34c10 100644
--- a/drivers/s390/char/sclp_cpi_sys.c
+++ b/drivers/s390/char/sclp_cpi_sys.c
@@ -84,7 +84,7 @@ static struct sclp_req *cpi_prepare_req(void)
 	req = kzalloc_obj(struct sclp_req);
 	if (!req)
 		return ERR_PTR(-ENOMEM);
-	sccb = (struct cpi_sccb *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	sccb = kzalloc(PAGE_SIZE, GFP_KERNEL | GFP_DMA);
 	if (!sccb) {
 		kfree(req);
 		return ERR_PTR(-ENOMEM);
@@ -118,7 +118,7 @@ static struct sclp_req *cpi_prepare_req(void)
 
 static void cpi_free_req(struct sclp_req *req)
 {
-	free_page((unsigned long) req->sccb);
+	kfree(req->sccb);
 	kfree(req);
 }
 

-- 
2.53.0