[PATCH 12/13] s390/qdio_setup: Use kzalloc() for the SSQD request

[Mike Rapoport (Microsoft)]

qdio_setup_get_ssqd() allocates the request block for the Store
Subchannel QDIO Data (SSQD) CHSC command.

This memory 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_free_page() with kzalloc() and free_page() with
kfree().

Link: https://lore.kernel.org/all/635405e4-9423-4a25-a6e7-e03c8ea0bcbe@xxxxxxxxxx
Assisted-by: copilot:claude-opus
Signed-off-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
---
 drivers/s390/cio/qdio_setup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/cio/qdio_setup.c b/drivers/s390/cio/qdio_setup.c
index 7ca8f61a2387b..c0215a7d29a81 100644
--- a/drivers/s390/cio/qdio_setup.c
+++ b/drivers/s390/cio/qdio_setup.c
@@ -249,7 +249,7 @@ int qdio_setup_get_ssqd(struct qdio_irq *irq_ptr,
 
 	DBF_EVENT("getssqd:%4x", schid->sch_no);
 	if (!irq_ptr) {
-		ssqd = (struct chsc_ssqd_area *)__get_free_page(GFP_KERNEL);
+		ssqd = kzalloc(PAGE_SIZE, GFP_KERNEL);
 		if (!ssqd)
 			return -ENOMEM;
 	} else {
@@ -270,7 +270,7 @@ int qdio_setup_get_ssqd(struct qdio_irq *irq_ptr,
 
 out:
 	if (!irq_ptr)
-		free_page((unsigned long)ssqd);
+		kfree(ssqd);
 
 	return rc;
 }

-- 
2.53.0