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From: Matthew Wilcox <willy@infradead.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-kernel@vger.kernel.org, Keith Busch <keith.busch@intel.com>,
	vishal.l.verma@intel.com, x86@kernel.org, linux-mm@kvack.org,
	linux-nvdimm@lists.01.org
Subject: Re: [RFC PATCH 2/5] lib/memregion: Uplevel the pmem "region" ida to a global allocator
Date: Thu, 4 Apr 2019 12:32:11 -0700
Message-ID: <20190404193211.GK22763@bombadil.infradead.org> (raw)
In-Reply-To: <155440491849.3190322.17551464505265122881.stgit@dwillia2-desk3.amr.corp.intel.com>

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?

  reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-04 19:08 [RFC PATCH 0/5] EFI Special Purpose Memory Support Dan Williams
2019-04-04 19:08 ` [RFC PATCH 1/5] efi: Detect UEFI 2.8 Special Purpose Memory Dan Williams
2019-04-06  4:21   ` Ard Biesheuvel
2019-04-09 16:43     ` Dan Williams
2019-04-09 17:21       ` Ard Biesheuvel
2019-04-10  2:10         ` Dan Williams
2019-04-12 20:43           ` Ard Biesheuvel
2019-04-12 21:18             ` Dan Williams
2019-04-15 11:43       ` Enrico Weigelt, metux IT consult
2019-04-04 19:08 ` [RFC PATCH 2/5] lib/memregion: Uplevel the pmem "region" ida to a global allocator Dan Williams
2019-04-04 19:32   ` Matthew Wilcox [this message]
2019-04-04 21:02     ` Dan Williams
2019-04-04 19:08 ` [RFC PATCH 3/5] acpi/hmat: Track target address ranges Dan Williams
2019-04-04 20:58   ` Keith Busch
2019-04-04 20:58     ` Dan Williams
2019-04-04 19:08 ` [RFC PATCH 4/5] acpi/hmat: Register special purpose memory as a device Dan Williams
2019-04-05 11:18   ` Jonathan Cameron
2019-04-05 15:43     ` Dan Williams
2019-04-05 16:23       ` Jonathan Cameron
2019-04-05 16:56         ` Dan Williams
2019-04-05 17:39           ` Jonathan Cameron
2019-04-09 12:13   ` Christoph Hellwig
2019-04-09 14:49     ` Dan Williams
2019-04-04 19:08 ` [RFC PATCH 5/5] device-dax: Add a driver for "hmem" devices Dan Williams

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