[PATCH 27/28] xor: use static_call for xor_gen

Christoph Hellwig
2026-03-27T06:23:44Z

Avoid the indirect call for xor_generation by using a static_call.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
lib/raid/xor/xor-core.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/lib/raid/xor/xor-core.c b/lib/raid/xor/xor-core.c
index 9e043d8c3a7a..bd4e6e434418 100644
--- a/lib/raid/xor/xor-core.c
+++ b/lib/raid/xor/xor-core.c
@@ -11,10 +11,10 @@
#include <linux/raid/xor.h>
#include <linux/jiffies.h>
#include <linux/preempt.h>
+#include <linux/static_call.h>
#include "xor_impl.h"

-/* The xor routine to use. */
-static struct xor_block_template *active_template;
+DEFINE_STATIC_CALL_NULL(xor_gen_impl, *xor_block_8regs.xor_gen);

/**
* xor_gen - generate RAID-style XOR information
@@ -37,13 +37,13 @@ void xor_gen(void *dest, void **srcs, unsigned int src_cnt, unsigned int bytes)
WARN_ON_ONCE(bytes == 0);
WARN_ON_ONCE(bytes & 511);

- active_template->xor_gen(dest, srcs, src_cnt, bytes);
+ static_call(xor_gen_impl)(dest, srcs, src_cnt, bytes);
}
EXPORT_SYMBOL(xor_gen);

/* Set of all registered templates. */
static struct xor_block_template *__initdata template_list;
-static bool __initdata xor_forced = false;
+static struct xor_block_template *forced_template;

/**
* xor_register - register a XOR template
@@ -69,7 +69,7 @@ void __init xor_register(struct xor_block_template *tmpl)
*/
void __init xor_force(struct xor_block_template *tmpl)
{
- active_template = tmpl;
+ forced_template = tmpl;
}

#define BENCH_SIZE 4096
@@ -111,7 +111,7 @@ static int __init calibrate_xor_blocks(void)
void *b1, *b2;
struct xor_block_template *f, *fastest;

- if (xor_forced)
+ if (forced_template)
return 0;

b1 = (void *) __get_free_pages(GFP_KERNEL, 2);
@@ -128,7 +128,7 @@ static int __init calibrate_xor_blocks(void)
if (f->speed > fastest->speed)
fastest = f;
}
- active_template = fastest;
+ static_call_update(xor_gen_impl, fastest->xor_gen);
pr_info("xor: using function: %s (%d MB/sec)\n",
fastest->name, fastest->speed);

@@ -156,10 +156,10 @@ static int __init xor_init(void)
* If this arch/cpu has a short-circuited selection, don't loop through
* all the possible functions, just use the best one.
*/
- if (active_template) {
+ if (forced_template) {
pr_info("xor: automatically using best checksumming function %-10s\n",
- active_template->name);
- xor_forced = true;
+ forced_template->name);
+ static_call_update(xor_gen_impl, forced_template->xor_gen);
return 0;
}

@@ -170,7 +170,7 @@ static int __init xor_init(void)
* Pick the first template as the temporary default until calibration
* happens.
*/
- active_template = template_list;
+ static_call_update(xor_gen_impl, template_list->xor_gen);
return 0;
#endif
}
--
2.47.3