[PATCH 12/14] s390/sclp_ftp: Replace get_zeroed_page() with kzalloc()

[Mike Rapoport (Microsoft)]

sclp_ftp_et7() allocates the SCCB used for an HMC file transfer request
and sclp_ftp_startup() allocates the SCCB used to read the SCLP info in
the debug code.

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@xxxxxxxxxx
Signed-off-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
---
 drivers/s390/char/sclp_ftp.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/s390/char/sclp_ftp.c b/drivers/s390/char/sclp_ftp.c
index 853492d53953c..c46fd056e9daf 100644
--- a/drivers/s390/char/sclp_ftp.c
+++ b/drivers/s390/char/sclp_ftp.c
@@ -93,7 +93,7 @@ static int sclp_ftp_et7(const struct hmcdrv_ftp_cmdspec *ftp)
 	int rc;
 
 	req = kzalloc_obj(*req);
-	sccb = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	sccb = kzalloc(PAGE_SIZE, GFP_KERNEL | GFP_DMA);
 	if (!req || !sccb) {
 		rc = -ENOMEM;
 		goto out_free;
@@ -155,7 +155,7 @@ static int sclp_ftp_et7(const struct hmcdrv_ftp_cmdspec *ftp)
 	}
 
 out_free:
-	free_page((unsigned long) sccb);
+	kfree(sccb);
 	kfree(req);
 	return rc;
 }
@@ -250,7 +250,7 @@ int sclp_ftp_startup(void)
 		return rc;
 
 #ifdef DEBUG
-	info = get_zeroed_page(GFP_KERNEL);
+	info = (unsigned long)kzalloc(PAGE_SIZE, GFP_KERNEL);
 
 	if (info != 0) {
 		struct sysinfo_2_2_2 *info222 = (struct sysinfo_2_2_2 *)info;
@@ -262,7 +262,7 @@ int sclp_ftp_startup(void)
 				 info222->lpar_number, info222->name);
 		}
 
-		free_page(info);
+		kfree((void *)info);
 	}
 #endif	/* DEBUG */
 	return 0;

-- 
2.53.0