[PATCH 03/14] s390/sclp_pci: Replace get_zeroed_page() with kzalloc()

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

do_pci_configure() and sclp_pci_report() allocate the SCCBs used to
(de)configure a PCI function and to report PCI errors to the SCLP.

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/sclp_pci.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/s390/char/sclp_pci.c b/drivers/s390/char/sclp_pci.c
index b79ef7006e46f..9e3d4b1015357 100644
--- a/drivers/s390/char/sclp_pci.c
+++ b/drivers/s390/char/sclp_pci.c
@@ -44,7 +44,7 @@ static int do_pci_configure(sclp_cmdw_t cmd, u32 fid)
 	if (!SCLP_HAS_PCI_RECONFIG)
 		return -EOPNOTSUPP;
 
-	sccb = (struct pci_cfg_sccb *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	sccb = kzalloc(PAGE_SIZE, GFP_KERNEL | GFP_DMA);
 	if (!sccb)
 		return -ENOMEM;
 
@@ -65,7 +65,7 @@ static int do_pci_configure(sclp_cmdw_t cmd, u32 fid)
 		break;
 	}
 out:
-	free_page((unsigned long) sccb);
+	kfree(sccb);
 	return rc;
 }
 
@@ -134,7 +134,7 @@ int sclp_pci_report(struct zpci_report_error_header *report, u32 fh, u32 fid)
 		goto out_unregister;
 	}
 
-	sccb = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	sccb = kzalloc(PAGE_SIZE, GFP_KERNEL | GFP_DMA);
 	if (!sccb) {
 		ret = -ENOMEM;
 		goto out_unregister;
@@ -177,7 +177,7 @@ int sclp_pci_report(struct zpci_report_error_header *report, u32 fh, u32 fid)
 	}
 
 out_free_req:
-	free_page((unsigned long) sccb);
+	kfree(sccb);
 out_unregister:
 	sclp_unregister(&sclp_pci_event);
 out_unlock:

-- 
2.53.0