github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-27 09:36:22 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

s390/trng: Replace __get_free_page() with kmalloc()

Browse Source 
trng_read() allocates a temporary staging buffer for CPACF TRNG
random data before copying it to 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
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Mike Rapoport (Microsoft) 2026-05-31 17:08:26 +03:00 committed by Alexander Gordeev
parent cccb81940a
commit b8bce5f118
1 changed files with 3 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/char/hw_random/s390-trng.c
View File

@ -20,6 +20,7 @@
#include <linux/atomic.h>
#include <linux/random.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <asm/debug.h>
#include <asm/cpacf.h>
#include <asm/archrandom.h>
@ -67,7 +68,7 @@ static ssize_t trng_read(struct file *file, char __user *ubuf,
*/
if (nbytes > sizeof(buf)) {
p = (u8 *) __get_free_page(GFP_KERNEL);
p = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!p)
return -ENOMEM;
}
@ -94,7 +95,7 @@ static ssize_t trng_read(struct file *file, char __user *ubuf,
}
if (p != buf)
free_page((unsigned long) p);
kfree(p);
DEBUG_DBG("trng_read()=%zd\n", ret);
return ret;