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xen: tmem: enable Xen tmem shim to be built/loaded as a module
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Allow Xen tmem shim to be built/loaded as a module.  Xen self-ballooning
and frontswap-selfshrinking are now also "lazily" initialized when the
Xen tmem shim is loaded as a module, unless explicitly disabled by
module parameters.

Note runtime dependency disallows loading if cleancache/frontswap lazy
initialization patches are not present.

If built-in (not built as a module), the original mechanism of enabling
via a kernel boot parameter is retained, but this should be considered
deprecated.

Note that module unload is explicitly not yet supported.

[v1: Removed the [CLEANCACHE|FRONTSWAP]_HAS_LAZY_INIT ifdef]
[v2: Squashed the xen/tmem: Remove the subsys call patch in]
[akpm@linux-foundation.org: fix build (disable_frontswap_selfshrinking undeclared)]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andor Daam <andor.daam@googlemail.com>
Cc: Florian Schmaus <fschmaus@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Stefan Hengelein <ilendir@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Dan Magenheimer authored and Linus Torvalds committed May 1, 2013
1 parent ff610a1 commit 10a7a07
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Showing 4 changed files with 46 additions and 19 deletions.
4 changes: 2 additions & 2 deletions drivers/xen/Kconfig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -145,9 +145,9 @@ config SWIOTLB_XEN
select SWIOTLB

config XEN_TMEM
bool
tristate
depends on !ARM
default y if (CLEANCACHE || FRONTSWAP)
default m if (CLEANCACHE || FRONTSWAP)
help
Shim to interface in-kernel Transcendent Memory hooks
(e.g. cleancache and frontswap) to Xen tmem hypercalls.
Expand Down
40 changes: 31 additions & 9 deletions drivers/xen/tmem.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
* Author: Dan Magenheimer
*/

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
Expand Down Expand Up @@ -128,6 +129,7 @@ static int xen_tmem_flush_object(u32 pool_id, struct tmem_oid oid)
return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, oid, 0, 0, 0, 0, 0);
}

#ifndef CONFIG_XEN_TMEM_MODULE
bool __read_mostly tmem_enabled = false;

static int __init enable_tmem(char *s)
Expand All @@ -136,6 +138,7 @@ static int __init enable_tmem(char *s)
return 1;
}
__setup("tmem", enable_tmem);
#endif

#ifdef CONFIG_CLEANCACHE
static int xen_tmem_destroy_pool(u32 pool_id)
Expand Down Expand Up @@ -227,14 +230,19 @@ static int tmem_cleancache_init_shared_fs(char *uuid, size_t pagesize)
return xen_tmem_new_pool(shared_uuid, TMEM_POOL_SHARED, pagesize);
}

static bool __initdata use_cleancache = true;

static bool disable_cleancache __read_mostly;
static bool disable_selfballooning __read_mostly;
#ifdef CONFIG_XEN_TMEM_MODULE
module_param(disable_cleancache, bool, S_IRUGO);
module_param(disable_selfballooning, bool, S_IRUGO);
#else
static int __init no_cleancache(char *s)
{
use_cleancache = false;
disable_cleancache = true;
return 1;
}
__setup("nocleancache", no_cleancache);
#endif

static struct cleancache_ops tmem_cleancache_ops = {
.put_page = tmem_cleancache_put_page,
Expand Down Expand Up @@ -353,14 +361,19 @@ static void tmem_frontswap_init(unsigned ignored)
xen_tmem_new_pool(private, TMEM_POOL_PERSIST, PAGE_SIZE);
}

static bool __initdata use_frontswap = true;

static bool disable_frontswap __read_mostly;
static bool disable_frontswap_selfshrinking __read_mostly;
#ifdef CONFIG_XEN_TMEM_MODULE
module_param(disable_frontswap, bool, S_IRUGO);
module_param(disable_frontswap_selfshrinking, bool, S_IRUGO);
#else
static int __init no_frontswap(char *s)
{
use_frontswap = false;
disable_frontswap = true;
return 1;
}
__setup("nofrontswap", no_frontswap);
#endif

static struct frontswap_ops tmem_frontswap_ops = {
.store = tmem_frontswap_store,
Expand All @@ -369,14 +382,16 @@ static struct frontswap_ops tmem_frontswap_ops = {
.invalidate_area = tmem_frontswap_flush_area,
.init = tmem_frontswap_init
};
#else /* CONFIG_FRONTSWAP */
#define disable_frontswap_selfshrinking 1
#endif

static int __init xen_tmem_init(void)
static int xen_tmem_init(void)
{
if (!xen_domain())
return 0;
#ifdef CONFIG_FRONTSWAP
if (tmem_enabled && use_frontswap) {
if (tmem_enabled && !disable_frontswap) {
char *s = "";
struct frontswap_ops *old_ops =
frontswap_register_ops(&tmem_frontswap_ops);
Expand All @@ -390,7 +405,7 @@ static int __init xen_tmem_init(void)
#endif
#ifdef CONFIG_CLEANCACHE
BUG_ON(sizeof(struct cleancache_filekey) != sizeof(struct tmem_oid));
if (tmem_enabled && use_cleancache) {
if (tmem_enabled && !disable_cleancache) {
char *s = "";
struct cleancache_ops *old_ops =
cleancache_register_ops(&tmem_cleancache_ops);
Expand All @@ -399,8 +414,15 @@ static int __init xen_tmem_init(void)
printk(KERN_INFO "cleancache enabled, RAM provided by "
"Xen Transcendent Memory%s\n", s);
}
#endif
#ifdef CONFIG_XEN_SELFBALLOONING
xen_selfballoon_init(!disable_selfballooning,
!disable_frontswap_selfshrinking);
#endif
return 0;
}

module_init(xen_tmem_init)
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dan Magenheimer <dan.magenheimer@oracle.com>");
MODULE_DESCRIPTION("Shim to Xen transcendent memory");
13 changes: 5 additions & 8 deletions drivers/xen/xen-selfballoon.c
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Original file line number Diff line number Diff line change
Expand Up @@ -121,7 +121,7 @@ static DECLARE_DELAYED_WORK(selfballoon_worker, selfballoon_process);
static bool frontswap_selfshrinking __read_mostly;

/* Enable/disable with kernel boot option. */
static bool use_frontswap_selfshrink __initdata = true;
static bool use_frontswap_selfshrink = true;

/*
* The default values for the following parameters were deemed reasonable
Expand Down Expand Up @@ -185,7 +185,7 @@ static int __init xen_nofrontswap_selfshrink_setup(char *s)
__setup("noselfshrink", xen_nofrontswap_selfshrink_setup);

/* Disable with kernel boot option. */
static bool use_selfballooning __initdata = true;
static bool use_selfballooning = true;

static int __init xen_noselfballooning_setup(char *s)
{
Expand All @@ -196,7 +196,7 @@ static int __init xen_noselfballooning_setup(char *s)
__setup("noselfballooning", xen_noselfballooning_setup);
#else /* !CONFIG_FRONTSWAP */
/* Enable with kernel boot option. */
static bool use_selfballooning __initdata = false;
static bool use_selfballooning;

static int __init xen_selfballooning_setup(char *s)
{
Expand Down Expand Up @@ -537,7 +537,7 @@ int register_xen_selfballooning(struct device *dev)
}
EXPORT_SYMBOL(register_xen_selfballooning);

static int __init xen_selfballoon_init(void)
int xen_selfballoon_init(bool use_selfballooning, bool use_frontswap_selfshrink)
{
bool enable = false;

Expand Down Expand Up @@ -571,7 +571,4 @@ static int __init xen_selfballoon_init(void)

return 0;
}

subsys_initcall(xen_selfballoon_init);

MODULE_LICENSE("GPL");
EXPORT_SYMBOL(xen_selfballoon_init);
8 changes: 8 additions & 0 deletions include/xen/tmem.h
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,15 @@

#include <linux/types.h>

#ifdef CONFIG_XEN_TMEM_MODULE
#define tmem_enabled true
#else
/* defined in drivers/xen/tmem.c */
extern bool tmem_enabled;
#endif

#ifdef CONFIG_XEN_SELFBALLOONING
extern int xen_selfballoon_init(bool, bool);
#endif

#endif /* _XEN_TMEM_H */

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