Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 623fd807 authored by Greg Thelen's avatar Greg Thelen Committed by Linus Torvalds
Browse files

percpu: add test module for various percpu operations 



Tests various percpu operations.

Enable with CONFIG_PERCPU_TEST=m.

Signed-off-by: default avatarGreg Thelen <gthelen@google.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3d035f58

lib/Kconfig.debug

+9 −0
Original line number Diff line number Diff line
@@ -1481,6 +1481,15 @@ config INTERVAL_TREE_TEST 
	help

	  A benchmark measuring the performance of the interval tree library



config PERCPU_TEST

	tristate "Per cpu operations test"

	depends on m && DEBUG_KERNEL

	help

	  Enable this option to build test module which validates per-cpu

	  operations.



	  If unsure, say N.



config ATOMIC64_SELFTEST

	bool "Perform an atomic64_t self-test at boot"

	help

lib/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -157,6 +157,8 @@ obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o 


interval_tree_test-objs := interval_tree_test_main.o interval_tree.o



obj-$(CONFIG_PERCPU_TEST) += percpu_test.o



obj-$(CONFIG_ASN1) += asn1_decoder.o



obj-$(CONFIG_FONT_SUPPORT) += fonts/

lib/percpu_test.c

0 → 100644
+138 −0
Original line number Diff line number Diff line 
#include <linux/module.h>



/* validate @native and @pcp counter values match @expected */

#define CHECK(native, pcp, expected)                                    \

	do {                                                            \

		WARN((native) != (expected),                            \

		     "raw %ld (0x%lx) != expected %lld (0x%llx)",	\

		     (native), (native),				\

		     (long long)(expected), (long long)(expected));	\

		WARN(__this_cpu_read(pcp) != (expected),                \

		     "pcp %ld (0x%lx) != expected %lld (0x%llx)",	\

		     __this_cpu_read(pcp), __this_cpu_read(pcp),	\

		     (long long)(expected), (long long)(expected));	\

	} while (0)



static DEFINE_PER_CPU(long, long_counter);

static DEFINE_PER_CPU(unsigned long, ulong_counter);



static int __init percpu_test_init(void)

{

	/*

	 * volatile prevents compiler from optimizing it uses, otherwise the

	 * +ul_one/-ul_one below would replace with inc/dec instructions.

	 */

	volatile unsigned int ui_one = 1;

	long l = 0;

	unsigned long ul = 0;



	pr_info("percpu test start\n");



	preempt_disable();



	l += -1;

	__this_cpu_add(long_counter, -1);

	CHECK(l, long_counter, -1);



	l += 1;

	__this_cpu_add(long_counter, 1);

	CHECK(l, long_counter, 0);



	ul = 0;

	__this_cpu_write(ulong_counter, 0);



	ul += 1UL;

	__this_cpu_add(ulong_counter, 1UL);

	CHECK(ul, ulong_counter, 1);



	ul += -1UL;

	__this_cpu_add(ulong_counter, -1UL);

	CHECK(ul, ulong_counter, 0);



	ul += -(unsigned long)1;

	__this_cpu_add(ulong_counter, -(unsigned long)1);

	CHECK(ul, ulong_counter, -1);



	ul = 0;

	__this_cpu_write(ulong_counter, 0);



	ul -= 1;

	__this_cpu_dec(ulong_counter);

	CHECK(ul, ulong_counter, -1);

	CHECK(ul, ulong_counter, ULONG_MAX);



	l += -ui_one;

	__this_cpu_add(long_counter, -ui_one);

	CHECK(l, long_counter, 0xffffffff);



	l += ui_one;

	__this_cpu_add(long_counter, ui_one);

	CHECK(l, long_counter, (long)0x100000000LL);





	l = 0;

	__this_cpu_write(long_counter, 0);



	l -= ui_one;

	__this_cpu_sub(long_counter, ui_one);

	CHECK(l, long_counter, -1);



	l = 0;

	__this_cpu_write(long_counter, 0);



	l += ui_one;

	__this_cpu_add(long_counter, ui_one);

	CHECK(l, long_counter, 1);



	l += -ui_one;

	__this_cpu_add(long_counter, -ui_one);

	CHECK(l, long_counter, (long)0x100000000LL);



	l = 0;

	__this_cpu_write(long_counter, 0);



	l -= ui_one;

	this_cpu_sub(long_counter, ui_one);

	CHECK(l, long_counter, -1);

	CHECK(l, long_counter, ULONG_MAX);



	ul = 0;

	__this_cpu_write(ulong_counter, 0);



	ul += ui_one;

	__this_cpu_add(ulong_counter, ui_one);

	CHECK(ul, ulong_counter, 1);



	ul = 0;

	__this_cpu_write(ulong_counter, 0);



	ul -= ui_one;

	__this_cpu_sub(ulong_counter, ui_one);

	CHECK(ul, ulong_counter, -1);

	CHECK(ul, ulong_counter, ULONG_MAX);



	ul = 3;

	__this_cpu_write(ulong_counter, 3);



	ul = this_cpu_sub_return(ulong_counter, ui_one);

	CHECK(ul, ulong_counter, 2);



	ul = __this_cpu_sub_return(ulong_counter, ui_one);

	CHECK(ul, ulong_counter, 1);



	preempt_enable();



	pr_info("percpu test done\n");

	return -EAGAIN;  /* Fail will directly unload the module */

}



static void __exit percpu_test_exit(void)

{

}



module_init(percpu_test_init)

module_exit(percpu_test_exit)



MODULE_LICENSE("GPL");

MODULE_AUTHOR("Greg Thelen");

MODULE_DESCRIPTION("percpu operations test");