[PATCH 7/7] Improve alloc_percpu: Simple testing patch.

[Rusty Russell]

Note that we can use the ptr ops on static percpu vars now.  We should
remove the "per_cpu__" token-pasting which was designed to catch raw
usage, and use sparse annotations instead.

Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
---
 include/linux/percpu.h |    2 +
 init/Kconfig           |    6 ++++
 init/Makefile          |    1
 init/main.c            |    1
 init/test-cpualloc.c   |   61 +++++++++++++++++++++++++++++++++++++++++++++++++
 mm/allocpercpu.c       |    7 ++---
 6 files changed, 74 insertions(+), 4 deletions(-)

diff -r 3b3fa686230f init/Kconfig
--- a/init/Kconfig	Mon Nov 17 23:19:14 2008 +1030
+++ b/init/Kconfig	Mon Nov 17 23:39:58 2008 +1030
@@ -929,3 +929,9 @@
 	  designed for best read-side performance on non-realtime
 	  systems.  Classic RCU is the default.  Note that the
 	  PREEMPT_RCU symbol is used to select/deselect this option.
+
+config TEST_CPUALLOC
+	tristate "Test alloc_percpu"
+	depends on DEBUG_KERNEL
+	help
+	  This tests the replacement alloc_percpu() implementation.
diff -r 3b3fa686230f init/Makefile
--- a/init/Makefile	Mon Nov 17 23:19:14 2008 +1030
+++ b/init/Makefile	Mon Nov 17 23:39:58 2008 +1030
@@ -9,6 +9,7 @@
 obj-$(CONFIG_BLK_DEV_INITRD)   += initramfs.o
 endif
 obj-$(CONFIG_GENERIC_CALIBRATE_DELAY) += calibrate.o
+obj-$(CONFIG_TEST_CPUALLOC) += test-cpualloc.o
 
 mounts-y			:= do_mounts.o
 mounts-$(CONFIG_BLK_DEV_RAM)	+= do_mounts_rd.o
diff -r 3b3fa686230f init/test-cpualloc.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/init/test-cpualloc.c	Mon Nov 17 23:39:58 2008 +1030
@@ -0,0 +1,75 @@
+/* Not a very informative test: it just crashes if something's wrong. */
+#include <linux/percpu.h>
+#include <linux/module.h>
+
+static DEFINE_PER_CPU(u64, static_pcpu);
+
+static int init(void)
+{
+	void *p, *thisp;
+	u64 *p64, *thisp64;
+	unsigned int i;
+
+	printk(KERN_INFO "Testing cpualloc for %u cpus\n",
+	       cpus_weight(cpu_possible_map));
+
+	p = __alloc_percpu(100, 128);
+	/* Don't expect failure. */
+	BUG_ON(!p);
+
+	thisp = get_cpu_ptr(p);
+	for_each_possible_cpu(i) {
+		unsigned int j;
+		/* Must be aligned. */
+		BUG_ON((unsigned long)per_cpu_ptr(p, i) % 128);
+		/* Must be zeroed. */
+		for (j = 0; j < 100; j++)
+			BUG_ON(((char *)per_cpu_ptr(p, i))[j]);
+		if (i == smp_processor_id())
+			BUG_ON(per_cpu_ptr(p, i) != thisp);
+		/* Check they're different pointers. */
+		memset(per_cpu_ptr(p, i), 0xFF, 100);
+	}
+	free_percpu(p);
+	put_cpu_ptr(p);
+
+	p64 = alloc_percpu(u64);
+	/* Don't expect failure. */
+	BUG_ON(!p64);
+
+	thisp64 = get_cpu_ptr(p64);
+	for_each_possible_cpu(i) {
+		/* Must be aligned. */
+		BUG_ON((unsigned long)per_cpu_ptr(p64, i) % __alignof__(u64));
+		/* Must be zeroed. */
+		BUG_ON(*per_cpu_ptr(p64, i));
+		if (i == smp_processor_id())
+			BUG_ON(per_cpu_ptr(p64, i) != thisp64);
+		/* Check they're different pointers. */
+		*per_cpu_ptr(p64, i) = -1ULL;
+	}
+	free_percpu(p64);
+	put_cpu_ptr(p64);
+
+	/* It even works on static percpu vars (though currently awkward) */
+	p64 = &per_cpu__static_pcpu;
+	thisp64 = get_cpu_ptr(p64);
+	for_each_possible_cpu(i) {
+		/* Must be aligned. */
+		BUG_ON((unsigned long)per_cpu_ptr(p64, i) % __alignof__(u64));
+		/* Must be zeroed. */
+		BUG_ON(*per_cpu_ptr(p64, i));
+		if (i == smp_processor_id())
+			BUG_ON(per_cpu_ptr(p64, i) != thisp64);
+		/* Check they're different pointers. */
+		*per_cpu_ptr(p64, i) = -1ULL;
+	}
+	put_cpu_ptr(p64);
+	return 0;
+}
+
+static void fini(void)
+{
+}
+module_init(init);
+module_exit(fini);

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