[RFC,2/5] lib/memregion: Uplevel the pmem "region" ida to a global allocator
diff mbox series

Message ID 155440491849.3190322.17551464505265122881.stgit@dwillia2-desk3.amr.corp.intel.com
State New
Headers show
Series
  • EFI Special Purpose Memory Support
Related show

Commit Message

Dan Williams April 4, 2019, 7:08 p.m. UTC
In preparation for handling platform differentiated memory types beyond
persistent memory, uplevel the "region" identifier to a global number
space. This enables a device-dax instance to be registered to any memory
type with guaranteed unique names.

Cc: Keith Busch <keith.busch@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/nvdimm/Kconfig       |    1 +
 drivers/nvdimm/core.c        |    1 -
 drivers/nvdimm/nd-core.h     |    1 -
 drivers/nvdimm/region_devs.c |   13 ++++---------
 include/linux/memregion.h    |    6 ++++++
 lib/Kconfig                  |    6 ++++++
 lib/Makefile                 |    1 +
 lib/memregion.c              |   22 ++++++++++++++++++++++
 8 files changed, 40 insertions(+), 11 deletions(-)
 create mode 100644 include/linux/memregion.h
 create mode 100644 lib/memregion.c

Comments

Matthew Wilcox April 4, 2019, 7:32 p.m. UTC | #1
On Thu, Apr 04, 2019 at 12:08:38PM -0700, Dan Williams wrote:
> +++ b/lib/Kconfig
> @@ -318,6 +318,12 @@ config DECOMPRESS_LZ4
>  config GENERIC_ALLOCATOR
>  	bool
>  
> +#
> +# Generic IDA for memory regions
> +#

Leaky abstraction -- nobody needs know that it's implemented as an IDA.
Suggest:

# Memory region ID allocation

...

> +++ b/lib/memregion.c
> @@ -0,0 +1,22 @@
> +#include <linux/idr.h>
> +#include <linux/module.h>
> +
> +static DEFINE_IDA(region_ida);
> +
> +int memregion_alloc(void)
> +{
> +	return ida_simple_get(&region_ida, 0, 0, GFP_KERNEL);
> +}
> +EXPORT_SYMBOL(memregion_alloc);
> +
> +void memregion_free(int id)
> +{
> +	ida_simple_remove(&region_ida, id);
> +}
> +EXPORT_SYMBOL(memregion_free);
> +
> +static void __exit memregion_exit(void)
> +{
> +	ida_destroy(&region_ida);
> +}
> +module_exit(memregion_exit);

 - Should these be EXPORT_SYMBOL_GPL?
 - Can we use the new interface, ida_alloc() and ida_free()?
 - Do we really want memregion_exit() to happen while there are still IDs
   allocated in the IDA?  I think this might well be better as:

	BUG_ON(!ida_empty(&region_ida));

Also, do we really want to call the structure the region_ida?  Why not
region_ids?
Dan Williams April 4, 2019, 9:02 p.m. UTC | #2
On Thu, Apr 4, 2019 at 12:32 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Thu, Apr 04, 2019 at 12:08:38PM -0700, Dan Williams wrote:
> > +++ b/lib/Kconfig
> > @@ -318,6 +318,12 @@ config DECOMPRESS_LZ4
> >  config GENERIC_ALLOCATOR
> >       bool
> >
> > +#
> > +# Generic IDA for memory regions
> > +#
>
> Leaky abstraction -- nobody needs know that it's implemented as an IDA.
> Suggest:
>
> # Memory region ID allocation
>

Looks good to me.

> ...
>
> > +++ b/lib/memregion.c
> > @@ -0,0 +1,22 @@
> > +#include <linux/idr.h>
> > +#include <linux/module.h>
> > +
> > +static DEFINE_IDA(region_ida);
> > +
> > +int memregion_alloc(void)
> > +{
> > +     return ida_simple_get(&region_ida, 0, 0, GFP_KERNEL);
> > +}
> > +EXPORT_SYMBOL(memregion_alloc);
> > +
> > +void memregion_free(int id)
> > +{
> > +     ida_simple_remove(&region_ida, id);
> > +}
> > +EXPORT_SYMBOL(memregion_free);
> > +
> > +static void __exit memregion_exit(void)
> > +{
> > +     ida_destroy(&region_ida);
> > +}
> > +module_exit(memregion_exit);
>
>  - Should these be EXPORT_SYMBOL_GPL?

I don't see the need. These are simple wrappers around existing
EXPORT_SYMBOL() exports, and there's little concern that these
interfaces might disappear in the future causing us pain with out of
tree modules as these don't touch anything in the core.

>  - Can we use the new interface, ida_alloc() and ida_free()?

Sure.

>  - Do we really want memregion_exit() to happen while there are still IDs
>    allocated in the IDA?  I think this might well be better as:
>
>         BUG_ON(!ida_empty(&region_ida));

True, or just delete the module_exit because this functionality can't
be built as a module, so the exit path is already dead code.

> Also, do we really want to call the structure the region_ida?  Why not
> region_ids?

Sure, sounds good.

Patch
diff mbox series

diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
index 5e27918e4624..bf26cc5f6d67 100644
--- a/drivers/nvdimm/Kconfig
+++ b/drivers/nvdimm/Kconfig
@@ -3,6 +3,7 @@  menuconfig LIBNVDIMM
 	depends on PHYS_ADDR_T_64BIT
 	depends on HAS_IOMEM
 	depends on BLK_DEV
+	select MEMREGION
 	help
 	  Generic support for non-volatile memory devices including
 	  ACPI-6-NFIT defined resources.  On platforms that define an
diff --git a/drivers/nvdimm/core.c b/drivers/nvdimm/core.c
index acce050856a8..75fe651d327d 100644
--- a/drivers/nvdimm/core.c
+++ b/drivers/nvdimm/core.c
@@ -463,7 +463,6 @@  static __exit void libnvdimm_exit(void)
 	nd_region_exit();
 	nvdimm_exit();
 	nvdimm_bus_exit();
-	nd_region_devs_exit();
 	nvdimm_devs_exit();
 }
 
diff --git a/drivers/nvdimm/nd-core.h b/drivers/nvdimm/nd-core.h
index e5ffd5733540..17561302dfec 100644
--- a/drivers/nvdimm/nd-core.h
+++ b/drivers/nvdimm/nd-core.h
@@ -133,7 +133,6 @@  struct nvdimm_bus *walk_to_nvdimm_bus(struct device *nd_dev);
 int __init nvdimm_bus_init(void);
 void nvdimm_bus_exit(void);
 void nvdimm_devs_exit(void);
-void nd_region_devs_exit(void);
 void nd_region_probe_success(struct nvdimm_bus *nvdimm_bus, struct device *dev);
 struct nd_region;
 void nd_region_create_ns_seed(struct nd_region *nd_region);
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index b4ef7d9ff22e..eefdfd2565dd 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -11,6 +11,7 @@ 
  * General Public License for more details.
  */
 #include <linux/scatterlist.h>
+#include <linux/memregion.h>
 #include <linux/highmem.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
@@ -27,7 +28,6 @@ 
  */
 #include <linux/io-64-nonatomic-hi-lo.h>
 
-static DEFINE_IDA(region_ida);
 static DEFINE_PER_CPU(int, flush_idx);
 
 static int nvdimm_map_flush(struct device *dev, struct nvdimm *nvdimm, int dimm,
@@ -141,7 +141,7 @@  static void nd_region_release(struct device *dev)
 		put_device(&nvdimm->dev);
 	}
 	free_percpu(nd_region->lane);
-	ida_simple_remove(&region_ida, nd_region->id);
+	memregion_free(nd_region->id);
 	if (is_nd_blk(dev))
 		kfree(to_nd_blk_region(dev));
 	else
@@ -1036,7 +1036,7 @@  static struct nd_region *nd_region_create(struct nvdimm_bus *nvdimm_bus,
 
 	if (!region_buf)
 		return NULL;
-	nd_region->id = ida_simple_get(&region_ida, 0, 0, GFP_KERNEL);
+	nd_region->id = memregion_alloc();
 	if (nd_region->id < 0)
 		goto err_id;
 
@@ -1090,7 +1090,7 @@  static struct nd_region *nd_region_create(struct nvdimm_bus *nvdimm_bus,
 	return nd_region;
 
  err_percpu:
-	ida_simple_remove(&region_ida, nd_region->id);
+	memregion_free(nd_region->id);
  err_id:
 	kfree(region_buf);
 	return NULL;
@@ -1237,8 +1237,3 @@  int nd_region_conflict(struct nd_region *nd_region, resource_size_t start,
 
 	return device_for_each_child(&nvdimm_bus->dev, &ctx, region_conflict);
 }
-
-void __exit nd_region_devs_exit(void)
-{
-	ida_destroy(&region_ida);
-}
diff --git a/include/linux/memregion.h b/include/linux/memregion.h
new file mode 100644
index 000000000000..99fa47793b49
--- /dev/null
+++ b/include/linux/memregion.h
@@ -0,0 +1,6 @@ 
+// SPDX-License-Identifier: GPL-2.0
+#ifndef _MEMREGION_H_
+#define _MEMREGION_H_
+int memregion_alloc(void);
+void memregion_free(int id);
+#endif /* _MEMREGION_H_ */
diff --git a/lib/Kconfig b/lib/Kconfig
index a9e56539bd11..0b765d9a1145 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -318,6 +318,12 @@  config DECOMPRESS_LZ4
 config GENERIC_ALLOCATOR
 	bool
 
+#
+# Generic IDA for memory regions
+#
+config MEMREGION
+	bool
+
 #
 # reed solomon support is select'ed if needed
 #
diff --git a/lib/Makefile b/lib/Makefile
index 3b08673e8881..6e237c4071af 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -122,6 +122,7 @@  obj-$(CONFIG_LIBCRC32C)	+= libcrc32c.o
 obj-$(CONFIG_CRC8)	+= crc8.o
 obj-$(CONFIG_XXHASH)	+= xxhash.o
 obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o
+obj-$(CONFIG_MEMREGION) += memregion.o
 
 obj-$(CONFIG_842_COMPRESS) += 842/
 obj-$(CONFIG_842_DECOMPRESS) += 842/
diff --git a/lib/memregion.c b/lib/memregion.c
new file mode 100644
index 000000000000..21f5ff96c2eb
--- /dev/null
+++ b/lib/memregion.c
@@ -0,0 +1,22 @@ 
+#include <linux/idr.h>
+#include <linux/module.h>
+
+static DEFINE_IDA(region_ida);
+
+int memregion_alloc(void)
+{
+	return ida_simple_get(&region_ida, 0, 0, GFP_KERNEL);
+}
+EXPORT_SYMBOL(memregion_alloc);
+
+void memregion_free(int id)
+{
+	ida_simple_remove(&region_ida, id);
+}
+EXPORT_SYMBOL(memregion_free);
+
+static void __exit memregion_exit(void)
+{
+	ida_destroy(&region_ida);
+}
+module_exit(memregion_exit);