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

Konrad Rzeszutek Wilk
2010-08-25T20:37:08Z

On Fri, Aug 20, 2010 at 11:50:43AM +0200, Michal Nazarewicz wrote:
> 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.

Whats the rationale for having those #ifdef CONFIG_CMA_SYSFS sprinkled
in the C code? Is SysFS not used on StrongARM? Why not implicitly include
the SysFS support?