github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-22 04:34:03 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

usb: core: devices: use kmalloc() to allocate dump buffer

Browse Source 
usb_device_dump() allocates a buffer for formatting
/sys/kernel/debug/usb/devices output text.

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_pages() with kmalloc() and free_pages() with
kfree().

Link: https://lore.kernel.org/all/635405e4-9423-4a25-a6e7-e03c8ea0bcbe@redhat.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://patch.msgid.link/20260701-b4-usb-v2-2-272807df4b64@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mike Rapoport (Microsoft) 2026-07-01 12:41:51 +03:00 committed by Greg Kroah-Hartman
parent 1b981fb482
commit 8a1f9d8590
1 changed files with 4 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/usb/core/devices.c
View File

@ -37,6 +37,7 @@
*/
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/usb.h>
@ -408,7 +409,7 @@ static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
return 0;
/* allocate 2^1 pages = 8K (on i386);
* should be more than enough for one device */
pages_start = (char *)__get_free_pages(GFP_NOIO, 1);
pages_start = kmalloc(PAGE_SIZE << 1, GFP_NOIO);
if (!pages_start)
return -ENOMEM;
@ -479,7 +480,7 @@ static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
if (length > *nbytes)
length = *nbytes;
if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
free_pages((unsigned long)pages_start, 1);
kfree(pages_start);
return -EFAULT;
}
*nbytes -= length;
@ -490,7 +491,7 @@ static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
} else
*skip_bytes -= length;
free_pages((unsigned long)pages_start, 1);
kfree(pages_start);
/* Now look at all of this device's children. */
usb_hub_for_each_child(usbdev, chix, childdev) {