[PATCH 1/4] USB: usbfs: replace __get_free_page() with kmalloc()

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

do_proc_control() allocates a temporary buffer for the data stage of a
control transfer issued from userspace.

This buffer 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 kmalloc() and free_page() with
kfree().

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

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 101cb9425480..9a7cc7cdf00b 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1190,7 +1190,7 @@ static int do_proc_control(struct usb_dev_state *ps,
 		return ret;
 
 	ret = -ENOMEM;
-	tbuf = (unsigned char *)__get_free_page(GFP_KERNEL);
+	tbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!tbuf)
 		goto done;
 	urb = usb_alloc_urb(0, GFP_NOIO);
@@ -1265,7 +1265,7 @@ static int do_proc_control(struct usb_dev_state *ps,
  done:
 	kfree(dr);
 	usb_free_urb(urb);
-	free_page((unsigned long) tbuf);
+	kfree(tbuf);
 	usbfs_decrease_memory_usage(PAGE_SIZE + sizeof(struct urb) +
 			sizeof(struct usb_ctrlrequest));
 	return ret;

-- 
2.53.0