[PATCH v2 08/13] s390/qdio_main: Use kzalloc() for the IRQ structure

[Mike Rapoport (Microsoft)]

qdio_allocate() allocates the QDIO irq structure.

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_zeroed_page() with kzalloc() and free_page() with
kfree().

While on it, drop the kmemleak exemption for the CCW. The IRQ structure
is now tracked, so kmemleak can find its pointer to the CCW.

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_main.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index d137bf8c70664..28eb8602ca97e 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -12,11 +12,11 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
-#include <linux/kmemleak.h>
 #include <linux/delay.h>
 #include <linux/gfp.h>
 #include <linux/io.h>
 #include <linux/atomic.h>
+#include <linux/slab.h>
 #include <asm/debug.h>
 #include <asm/qdio.h>
 #include <asm/asm.h>
@@ -936,7 +936,7 @@ int qdio_free(struct ccw_device *cdev)
 	free_page((unsigned long) irq_ptr->qdr);
 	kfree(irq_ptr->chsc_page);
 	kfree(irq_ptr->ccw);
-	free_page((unsigned long) irq_ptr);
+	kfree(irq_ptr);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(qdio_free);
@@ -961,7 +961,7 @@ int qdio_allocate(struct ccw_device *cdev, unsigned int no_input_qs,
 	    no_output_qs > QDIO_MAX_QUEUES_PER_IRQ)
 		return -EINVAL;
 
-	irq_ptr = (void *) get_zeroed_page(GFP_KERNEL);
+	irq_ptr = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!irq_ptr)
 		return -ENOMEM;
 
@@ -969,9 +969,6 @@ int qdio_allocate(struct ccw_device *cdev, unsigned int no_input_qs,
 	if (!irq_ptr->ccw)
 		goto err_ccw;
 
-	/* kmemleak doesn't scan the page-allocated irq_ptr: */
-	kmemleak_not_leak(irq_ptr->ccw);
-
 	irq_ptr->cdev = cdev;
 	mutex_init(&irq_ptr->setup_mutex);
 	if (qdio_allocate_dbf(irq_ptr))
@@ -1011,7 +1008,7 @@ int qdio_allocate(struct ccw_device *cdev, unsigned int no_input_qs,
 err_dbf:
 	kfree(irq_ptr->ccw);
 err_ccw:
-	free_page((unsigned long) irq_ptr);
+	kfree(irq_ptr);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(qdio_allocate);

-- 
2.53.0