[PATCH/RFCv4 3/6] mm: cma: Added SysFS support

Michal Nazarewicz
2010-08-20T09:50:43Z

The SysFS development interface lets one change the map attribute
at run time as well as observe what regions have been reserved.

Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
.../ABI/testing/sysfs-kernel-mm-contiguous | 53 +++
Documentation/contiguous-memory.txt | 4 +
include/linux/cma.h | 7 +
mm/Kconfig | 18 +-
mm/cma.c | 345 +++++++++++++++++++-
5 files changed, 423 insertions(+), 4 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-kernel-mm-contiguous

diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-contiguous b/Documentation/ABI/testing/sysfs-kernel-mm-contiguous
new file mode 100644
index 0000000..8df15bc
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-contiguous
@@ -0,0 +1,53 @@
+What: /sys/kernel/mm/contiguous/
+Date: August 2010
+Contact: Michal Nazarewicz <m.nazarewicz@samsung.com>
+Description:
+ If CMA has been built with SysFS support,
+ /sys/kernel/mm/contiguous/ contains a file called
+ "map", a file called "allocators" and a directory
+ called "regions".
+
+ The "map" file lets one change the CMA's map attribute
+ at run-time.
+
+ The "allocators" file list all registered allocators.
+ Allocators with no name are listed as a single minus
+ sign.
+
+ The "regions" directory list all reserved regions.
+
+ For more details see
+ Documentation/contiguous-memory.txt.
+
+What: /sys/kernel/mm/contiguous/regions/
+Date: August 2010
+Contact: Michal Nazarewicz <m.nazarewicz@samsung.com>
+Description:
+ The /sys/kernel/mm/contiguous/regions/ directory
+ contain directories for each registered CMA region.
+ The name of the directory is the same as the start
+ address of the region.
+
+ If region is named there is also a symbolic link named
+ like the region pointing to the region's directory.
+
+ Such directory contains the following files:
+
+ * "name" -- the name of the region or an empty file
+ * "start" -- starting address of the region (formatted
+ with %p, ie. hex).
+ * "size" -- size of the region (in bytes).
+ * "free" -- free space in the region (in bytes).
+ * "users" -- number of chunks allocated in the region.
+ * "alloc" -- name of the allocator.
+
+ If allocator is not attached to the region, "alloc" is
+ either the name of desired allocator in square
+ brackets (ie. "[foo]") or an empty file if region is
+ to be attached to default allocator. If an allocator
+ is attached to the region. "alloc" is either its name
+ or "-" if attached allocator has no name.
+
+ If there are no chunks allocated in given region
+ ("users" is "0") then a name of desired allocator can
+ be written to "alloc".
diff --git a/Documentation/contiguous-memory.txt b/Documentation/contiguous-memory.txt
index 8fc2400..8d189b8 100644
--- a/Documentation/contiguous-memory.txt
+++ b/Documentation/contiguous-memory.txt
@@ -256,6 +256,10 @@
iff it matched in previous pattern. If the second part is
omitted it will mach any type of memory requested by device.

+ If SysFS support is enabled, this attribute is accessible via
+ SysFS and can be changed at run-time by writing to
+ /sys/kernel/mm/contiguous/map.
+
Some examples (whitespace added for better readability):

cma_map = foo/quaz = r1;
diff --git a/include/linux/cma.h b/include/linux/cma.h
index cd63f52..eede28d 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -17,6 +17,9 @@

#include <linux/rbtree.h>
#include <linux/list.h>
+#if defined CONFIG_CMA_SYSFS
+# include <linux/kobject.h>
+#endif

struct device;
@@ -203,6 +206,10 @@ struct cma_region {
unsigned users;
struct list_head list;

+#if defined CONFIG_CMA_SYSFS
+ struct kobject kobj;
+#endif
+
unsigned used:1;
unsigned registered:1;
unsigned reserved:1;
diff --git a/mm/Kconfig b/mm/Kconfig
index 3e9317c..ac0bb08 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -319,12 +319,26 @@ config CMA
To make use of CMA you need to specify the regions and
driver->region mapping on command line when booting the kernel.

-config CMA_DEBUG
- bool "CMA debug messages (DEVELOPEMENT)"
+config CMA_DEVELOPEMENT
+ bool "Include CMA developement features"
depends on CMA
help
+ This lets you enable some developement features of the CMA
+ freamework.
+
+config CMA_DEBUG
+ bool "CMA debug messages"
+ depends on CMA_DEVELOPEMENT
+ help
Enable debug messages in CMA code.

+config CMA_SYSFS
+ bool "CMA SysFS interface support"
+ depends on CMA_DEVELOPEMENT
+ help
+ Enable support for SysFS interface.
+
+config CMA_CMDLINE
config CMA_BEST_FIT
bool "CMA best-fit allocator"
depends on CMA
diff --git a/mm/cma.c b/mm/cma.c
index 401399c..561d817 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -38,8 +38,8 @@

/*
- * Protects cma_regions, cma_allocators, cma_map, cma_map_length, and
- * cma_chunks_by_start.
+ * Protects cma_regions, cma_allocators, cma_map, cma_map_length,
+ * cma_kobj, cma_sysfs_regions and cma_chunks_by_start.
*/
static DEFINE_MUTEX(cma_mutex);

@@ -143,7 +143,11 @@ int __init __must_check cma_early_region_register(struct cma_region *reg)

/************************* Regions & Allocators *************************/

+static void __cma_sysfs_region_add(struct cma_region *reg);
+
static int __cma_region_attach_alloc(struct cma_region *reg);
+static void __maybe_unused __cma_region_detach_alloc(struct cma_region *reg);
+

/* List of all regions. Named regions are kept before unnamed. */
static LIST_HEAD(cma_regions);
@@ -226,6 +230,8 @@ int __must_check cma_region_register(struct cma_region *reg)
else
list_add_tail(&reg->list, &cma_regions);

+ __cma_sysfs_region_add(reg);
+
done:
mutex_unlock(&cma_mutex);

@@ -483,6 +489,329 @@ subsys_initcall(cma_init);

+/************************* SysFS *************************/
+
+#if defined CONFIG_CMA_SYSFS
+
+static struct kobject cma_sysfs_regions;
+static int cma_sysfs_regions_ready;
+
+
+#define CMA_ATTR_INLINE(_type, _name) \
+ (&((struct cma_ ## _type ## _attribute){ \
+ .attr = { \
+ .name = __stringify(_name), \
+ .mode = 0644, \
+ }, \
+ .show = cma_sysfs_ ## _type ## _ ## _name ## _show, \
+ .store = cma_sysfs_ ## _type ## _ ## _name ## _store, \
+ }).attr)
+
+#define CMA_ATTR_RO_INLINE(_type, _name) \
+ (&((struct cma_ ## _type ## _attribute){ \
+ .attr = { \
+ .name = __stringify(_name), \
+ .mode = 0444, \
+ }, \
+ .show = cma_sysfs_ ## _type ## _ ## _name ## _show, \
+ }).attr)
+
+
+struct cma_root_attribute {
+ struct attribute attr;
+ ssize_t (*show)(char *buf);
+ int (*store)(const char *buf);
+};
+
+static ssize_t cma_sysfs_root_map_show(char *page)
+{
+ ssize_t len;
+
+ len = cma_map_length;
+ if (!len) {
+ *page = 0;
+ len = 0;
+ } else {
+ if (len > (size_t)PAGE_SIZE - 1)
+ len = (size_t)PAGE_SIZE - 1;
+ memcpy(page, cma_map, len);
+ page[len++] = '\n';
+ }
+
+ return len;
+}
+
+static int cma_sysfs_root_map_store(const char *page)
+{
+ ssize_t len = cma_map_validate(page);
+ char *val = NULL;
+
+ if (len < 0)
+ return len;
+
+ if (len) {
+ val = kmemdup(page, len + 1, GFP_KERNEL);
+ if (!val)
+ return -ENOMEM;
+ val[len] = '\0';
+ }
+
+ kfree(cma_map);
+ cma_map = val;
+ cma_map_length = len;
+
+ return 0;
+}
+
+static ssize_t cma_sysfs_root_allocators_show(char *page)
+{
+ struct cma_allocator *alloc;
+ size_t left = PAGE_SIZE;
+ char *ch = page;
+
+ cma_foreach_allocator(alloc) {
+ ssize_t l = snprintf(ch, left, "%s ", alloc->name ?: "-");
+ ch += l;
+ left -= l;
+ }
+
+ if (ch != page)
+ ch[-1] = '\n';
+ return ch - page;
+}
+
+static ssize_t
+cma_sysfs_root_show(struct kobject *kobj, struct attribute *attr, char *buf)
+{
+ struct cma_root_attribute *rattr =
+ container_of(attr, struct cma_root_attribute, attr);
+ ssize_t ret;
+
+ mutex_lock(&cma_mutex);
+ ret = rattr->show(buf);
+ mutex_unlock(&cma_mutex);
+
+ return ret;
+}
+
+static ssize_t
+cma_sysfs_root_store(struct kobject *kobj, struct attribute *attr,
+ const char *buf, size_t count)
+{
+ struct cma_root_attribute *rattr =
+ container_of(attr, struct cma_root_attribute, attr);
+ int ret;
+
+ mutex_lock(&cma_mutex);
+ ret = rattr->store(buf);
+ mutex_unlock(&cma_mutex);
+
+ return ret < 0 ? ret : count;
+}
+
+static struct kobj_type cma_sysfs_root_type = {
+ .sysfs_ops = &(const struct sysfs_ops){
+ .show = cma_sysfs_root_show,
+ .store = cma_sysfs_root_store,
+ },
+ .default_attrs = (struct attribute * []) {
+ CMA_ATTR_INLINE(root, map),
+ CMA_ATTR_RO_INLINE(root, allocators),
+ NULL
+ },
+};
+
+static int __init cma_sysfs_init(void)
+{
+ static struct kobject root;
+ static struct kobj_type fake_type;
+
+ struct cma_region *reg;
+ int ret;
+
+ /* Root */
+ ret = kobject_init_and_add(&root, &cma_sysfs_root_type,
+ mm_kobj, "contiguous");
+ if (unlikely(ret < 0)) {
+ pr_err("init: unable to add root kobject: %d\n", ret);
+ return ret;
+ }
+
+ /* Regions */
+ ret = kobject_init_and_add(&cma_sysfs_regions, &fake_type,
+ &root, "regions");
+ if (unlikely(ret < 0)) {
+ pr_err("init: unable to add regions kobject: %d\n", ret);
+ return ret;
+ }
+
+ mutex_lock(&cma_mutex);
+ cma_sysfs_regions_ready = 1;
+ cma_foreach_region(reg)
+ __cma_sysfs_region_add(reg);
+ mutex_unlock(&cma_mutex);
+
+ return 0;
+}
+device_initcall(cma_sysfs_init);
+
+
+
+struct cma_region_attribute {
+ struct attribute attr;
+ ssize_t (*show)(struct cma_region *reg, char *buf);
+ int (*store)(struct cma_region *reg, const char *buf);
+};
+
+
+static ssize_t cma_sysfs_region_name_show(struct cma_region *reg, char *page)
+{
+ return reg->name ? snprintf(page, PAGE_SIZE, "%s\n", reg->name) : 0;
+}
+
+static ssize_t cma_sysfs_region_start_show(struct cma_region *reg, char *page)
+{
+ return snprintf(page, PAGE_SIZE, "%p\n", (void *)reg->start);
+}
+
+static ssize_t cma_sysfs_region_size_show(struct cma_region *reg, char *page)
+{
+ return snprintf(page, PAGE_SIZE, "%zu\n", reg->size);
+}
+
+static ssize_t cma_sysfs_region_free_show(struct cma_region *reg, char *page)
+{
+ return snprintf(page, PAGE_SIZE, "%zu\n", reg->free_space);
+}
+
+static ssize_t cma_sysfs_region_users_show(struct cma_region *reg, char *page)
+{
+ return snprintf(page, PAGE_SIZE, "%u\n", reg->users);
+}
+
+static ssize_t cma_sysfs_region_alloc_show(struct cma_region *reg, char *page)
+{
+ if (reg->alloc)
+ return snprintf(page, PAGE_SIZE, "%s\n",
+ reg->alloc->name ?: "-");
+ else if (reg->alloc_name)
+ return snprintf(page, PAGE_SIZE, "[%s]\n", reg->alloc_name);
+ else
+ return 0;
+}
+
+static int
+cma_sysfs_region_alloc_store(struct cma_region *reg, const char *page)
+{
+ char *s;
+
+ if (reg->alloc && reg->users)
+ return -EBUSY;
+
+ if (!*page || *page == '\n') {
+ s = NULL;
+ } else {
+ size_t len;
+
+ for (s = (char *)page; *++s && *s != '\n'; )
+ /* nop */;
+
+ len = s - page;
+ s = kmemdup(page, len + 1, GFP_KERNEL);
+ if (!s)
+ return -ENOMEM;
+ s[len] = '\0';
+ }
+
+ if (reg->alloc)
+ __cma_region_detach_alloc(reg);
+
+ if (reg->free_alloc_name)
+ kfree(reg->alloc_name);
+
+ reg->alloc_name = s;
+ reg->free_alloc_name = !!s;
+
+ return 0;
+}
+
+
+static ssize_t
+cma_sysfs_region_show(struct kobject *kobj, struct attribute *attr,
+ char *buf)
+{
+ struct cma_region *reg = container_of(kobj, struct cma_region, kobj);
+ struct cma_region_attribute *rattr =
+ container_of(attr, struct cma_region_attribute, attr);
+ ssize_t ret;
+
+ mutex_lock(&cma_mutex);
+ ret = rattr->show(reg, buf);
+ mutex_unlock(&cma_mutex);
+
+ return ret;
+}
+
+static int
+cma_sysfs_region_store(struct kobject *kobj, struct attribute *attr,
+ const char *buf, size_t count)
+{
+ struct cma_region *reg = container_of(kobj, struct cma_region, kobj);
+ struct cma_region_attribute *rattr =
+ container_of(attr, struct cma_region_attribute, attr);
+ int ret;
+
+ mutex_lock(&cma_mutex);
+ ret = rattr->store(reg, buf);
+ mutex_unlock(&cma_mutex);
+
+ return ret < 0 ? ret : count;
+}
+
+static struct kobj_type cma_sysfs_region_type = {
+ .sysfs_ops = &(const struct sysfs_ops){
+ .show = cma_sysfs_region_show,
+ .store = cma_sysfs_region_store,
+ },
+ .default_attrs = (struct attribute * []) {
+ CMA_ATTR_RO_INLINE(region, name),
+ CMA_ATTR_RO_INLINE(region, start),
+ CMA_ATTR_RO_INLINE(region, size),
+ CMA_ATTR_RO_INLINE(region, free),
+ CMA_ATTR_RO_INLINE(region, users),
+ CMA_ATTR_INLINE(region, alloc),
+ NULL
+ },
+};
+
+static void __cma_sysfs_region_add(struct cma_region *reg)
+{
+ int ret;
+
+ if (!cma_sysfs_regions_ready)
+ return;
+
+ memset(&reg->kobj, 0, sizeof reg->kobj);
+
+ ret = kobject_init_and_add(&reg->kobj, &cma_sysfs_region_type,
+ &cma_sysfs_regions,
+ "%p", (void *)reg->start);
+
+ if (reg->name &&
+ sysfs_create_link(&cma_sysfs_regions, &reg->kobj, reg->name) < 0)
+ /* Ignore any errors. */;
+}
+
+#else
+
+static void __cma_sysfs_region_add(struct cma_region *reg)
+{
+ /* nop */
+}
+
+#endif
+
+
/************************* Chunks *************************/

/* All chunks sorted by start address. */
@@ -784,6 +1113,18 @@ static int __cma_region_attach_alloc(struct cma_region *reg)
return ret;
}

+static void __cma_region_detach_alloc(struct cma_region *reg)
+{
+ if (!reg->alloc)
+ return;
+
+ if (reg->alloc->cleanup)
+ reg->alloc->cleanup(reg);
+
+ reg->alloc = NULL;
+ reg->used = 1;
+}
+

/*
* s ::= rules
--
1.7.1