[PATCH net-next] ptp: ocp: replace __get_free_page() with kmalloc()

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

ptp_ocp_summary_show() allocates a temporary buffer for formatting
PTP OCP device summary information.

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
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
This is a (small) part of larger work of replacing page allocator calls
with kmalloc.

Largely, anything that doesn't need struct page (or a memdesc in the
future) should just use kmalloc() or kvmalloc() to allocate memory.
Removing needless calls to page allocator helps with memdesc (aka project
folio) conversion and gives a nicer API without casts.
---
 drivers/ptp/ptp_ocp.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
index 625a85b2dc7e5..decc56892059b 100644
--- a/drivers/ptp/ptp_ocp.c
+++ b/drivers/ptp/ptp_ocp.c
@@ -18,6 +18,7 @@
 #include <linux/spi/spi.h>
 #include <linux/spi/xilinx_spi.h>
 #include <linux/spi/altera.h>
+#include <linux/slab.h>
 #include <net/devlink.h>
 #include <linux/i2c.h>
 #include <linux/iopoll.h>
@@ -5281,7 +5282,7 @@ ptp_ocp_summary_show(struct seq_file *s, void *data)
 	bool on, map;
 	int i;
 
-	buf = (char *)__get_free_page(GFP_KERNEL);
+	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -5497,7 +5498,7 @@ ptp_ocp_summary_show(struct seq_file *s, void *data)
 			   post_ns - pre_ns);
 	}
 
-	free_page((unsigned long)buf);
+	kfree(buf);
 	return 0;
 }
 DEFINE_SHOW_ATTRIBUTE(ptp_ocp_summary);

---
base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
change-id: 20260624-b4-ptp-ed56a38a6afd

--
Sincerely yours,
Mike.