[PATCH 2/4] USB: cxacru: replace __get_free_page() with kmalloc()

[Mike Rapoport (Microsoft)]

cxacru_fw() allocates a temporary buffer used to feed the firmware to the
device and cxacru_bind() allocates the transfer buffers for the command
URBs.

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_free_page() with kmalloc() 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/usb/atm/cxacru.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/atm/cxacru.c b/drivers/usb/atm/cxacru.c
index 636f7886fc26..75d87c31e81f 100644
--- a/drivers/usb/atm/cxacru.c
+++ b/drivers/usb/atm/cxacru.c
@@ -942,7 +942,7 @@ static int cxacru_fw(struct usb_device *usb_dev, enum cxacru_fw_request fw,
 	int offd, offb;
 	const int stride = CMD_PACKET_SIZE - 8;
 
-	buf = (u8 *) __get_free_page(GFP_KERNEL);
+	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -978,7 +978,7 @@ static int cxacru_fw(struct usb_device *usb_dev, enum cxacru_fw_request fw,
 	ret = 0;
 
 cleanup:
-	free_page((unsigned long) buf);
+	kfree(buf);
 	return ret;
 }
 
@@ -1146,13 +1146,13 @@ static int cxacru_bind(struct usbatm_data *usbatm_instance,
 
 	mutex_init(&instance->adsl_state_serialize);
 
-	instance->rcv_buf = (u8 *) __get_free_page(GFP_KERNEL);
+	instance->rcv_buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!instance->rcv_buf) {
 		usb_dbg(usbatm_instance, "cxacru_bind: no memory for rcv_buf\n");
 		ret = -ENOMEM;
 		goto fail;
 	}
-	instance->snd_buf = (u8 *) __get_free_page(GFP_KERNEL);
+	instance->snd_buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!instance->snd_buf) {
 		usb_dbg(usbatm_instance, "cxacru_bind: no memory for snd_buf\n");
 		ret = -ENOMEM;
@@ -1220,8 +1220,8 @@ static int cxacru_bind(struct usbatm_data *usbatm_instance,
 	return 0;
 
  fail:
-	free_page((unsigned long) instance->snd_buf);
-	free_page((unsigned long) instance->rcv_buf);
+	kfree(instance->snd_buf);
+	kfree(instance->rcv_buf);
 	usb_free_urb(instance->snd_urb);
 	usb_free_urb(instance->rcv_urb);
 	kfree(instance);
@@ -1254,8 +1254,8 @@ static void cxacru_unbind(struct usbatm_data *usbatm_instance,
 	usb_free_urb(instance->snd_urb);
 	usb_free_urb(instance->rcv_urb);
 
-	free_page((unsigned long) instance->snd_buf);
-	free_page((unsigned long) instance->rcv_buf);
+	kfree(instance->snd_buf);
+	kfree(instance->rcv_buf);
 
 	kfree(instance);
 

-- 
2.53.0