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memremap: provide an optional internal refcount in struct dev_pagemap 

Provide an internal refcounting logic if no ->ref field is provided
in the pagemap passed into devm_memremap_pages so that callers don't
have to reinvent it poorly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Christoph Hellwig 2019-06-26 14:27:14 +02:00 committed by Jason Gunthorpe
parent 514caf23a7
commit 24917f6b10
3 changed files with 100 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/memremap.h
View File

@ -95,6 +95,8 @@ struct dev_pagemap_ops {
* @altmap: pre-allocated/reserved memory for vmemmap allocations
* @res: physical address range covered by @ref
* @ref: reference count that pins the devm_memremap_pages() mapping
* @internal_ref: internal reference if @ref is not provided by the caller
* @done: completion for @internal_ref
* @dev: host device of the mapping for debug
* @data: private data pointer for page_free()
* @type: memory type: see MEMORY_* in memory_hotplug.h
@ -105,6 +107,8 @@ struct dev_pagemap {
struct vmem_altmap altmap;
struct resource res;
struct percpu_ref *ref;
struct percpu_ref internal_ref;
struct completion done;
struct device *dev;
enum memory_type type;
unsigned int flags;

64
kernel/memremap.c
View File

@ -29,7 +29,7 @@ static void devmap_managed_enable_put(void *data)
static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap)
{
if (!pgmap->ops->page_free) {
if (!pgmap->ops || !pgmap->ops->page_free) {
WARN(1, "Missing page_free method\n");
return -EINVAL;
}
@ -75,6 +75,24 @@ static unsigned long pfn_next(unsigned long pfn)
#define for_each_device_pfn(pfn, map) \
for (pfn = pfn_first(map); pfn < pfn_end(map); pfn = pfn_next(pfn))
static void dev_pagemap_kill(struct dev_pagemap *pgmap)
{
if (pgmap->ops && pgmap->ops->kill)
pgmap->ops->kill(pgmap);
else
percpu_ref_kill(pgmap->ref);
}
static void dev_pagemap_cleanup(struct dev_pagemap *pgmap)
{
if (pgmap->ops && pgmap->ops->cleanup) {
pgmap->ops->cleanup(pgmap);
} else {
wait_for_completion(&pgmap->done);
percpu_ref_exit(pgmap->ref);
}
}
static void devm_memremap_pages_release(void *data)
{
struct dev_pagemap *pgmap = data;
@ -84,10 +102,10 @@ static void devm_memremap_pages_release(void *data)
unsigned long pfn;
int nid;
pgmap->ops->kill(pgmap);
dev_pagemap_kill(pgmap);
for_each_device_pfn(pfn, pgmap)
put_page(pfn_to_page(pfn));
pgmap->ops->cleanup(pgmap);
dev_pagemap_cleanup(pgmap);
/* pages are dead and unused, undo the arch mapping */
align_start = res->start & ~(SECTION_SIZE - 1);
@ -114,20 +132,29 @@ static void devm_memremap_pages_release(void *data)
"%s: failed to free all reserved pages\n", __func__);
}
static void dev_pagemap_percpu_release(struct percpu_ref *ref)
{
struct dev_pagemap *pgmap =
container_of(ref, struct dev_pagemap, internal_ref);
complete(&pgmap->done);
}
/**
* devm_memremap_pages - remap and provide memmap backing for the given resource
* @dev: hosting device for @res
* @pgmap: pointer to a struct dev_pagemap
*
* Notes:
* 1/ At a minimum the res, ref and type and ops members of @pgmap must be
* initialized by the caller before passing it to this function
* 1/ At a minimum the res and type members of @pgmap must be initialized
* by the caller before passing it to this function
*
* 2/ The altmap field may optionally be initialized, in which case
* PGMAP_ALTMAP_VALID must be set in pgmap->flags.
*
* 3/ pgmap->ref must be 'live' on entry and will be killed and reaped
* at devm_memremap_pages_release() time, or if this routine fails.
* 3/ The ref field may optionally be provided, in which pgmap->ref must be
* 'live' on entry and will be killed and reaped at
* devm_memremap_pages_release() time, or if this routine fails.
*
* 4/ res is expected to be a host memory range that could feasibly be
* treated as a "System RAM" range, i.e. not a device mmio range, but
@ -175,10 +202,21 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
break;
}
if (!pgmap->ref || !pgmap->ops || !pgmap->ops->kill ||
!pgmap->ops->cleanup) {
WARN(1, "Missing reference count teardown definition\n");
return ERR_PTR(-EINVAL);
if (!pgmap->ref) {
if (pgmap->ops && (pgmap->ops->kill || pgmap->ops->cleanup))
return ERR_PTR(-EINVAL);
init_completion(&pgmap->done);
error = percpu_ref_init(&pgmap->internal_ref,
dev_pagemap_percpu_release, 0, GFP_KERNEL);
if (error)
return ERR_PTR(error);
pgmap->ref = &pgmap->internal_ref;
} else {
if (!pgmap->ops || !pgmap->ops->kill || !pgmap->ops->cleanup) {
WARN(1, "Missing reference count teardown definition\n");
return ERR_PTR(-EINVAL);
}
}
if (need_devmap_managed) {
@ -296,8 +334,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
err_pfn_remap:
pgmap_array_delete(res);
err_array:
pgmap->ops->kill(pgmap);
pgmap->ops->cleanup(pgmap);
dev_pagemap_kill(pgmap);
dev_pagemap_cleanup(pgmap);
return ERR_PTR(error);
}
EXPORT_SYMBOL_GPL(devm_memremap_pages);

56
tools/testing/nvdimm/test/iomap.c
View File

@ -100,26 +100,60 @@ static void nfit_test_kill(void *_pgmap)
{
struct dev_pagemap *pgmap = _pgmap;
WARN_ON(!pgmap || !pgmap->ref || !pgmap->ops || !pgmap->ops->kill ||
!pgmap->ops->cleanup);
pgmap->ops->kill(pgmap);
pgmap->ops->cleanup(pgmap);
WARN_ON(!pgmap || !pgmap->ref);
if (pgmap->ops && pgmap->ops->kill)
pgmap->ops->kill(pgmap);
else
percpu_ref_kill(pgmap->ref);
if (pgmap->ops && pgmap->ops->cleanup) {
pgmap->ops->cleanup(pgmap);
} else {
wait_for_completion(&pgmap->done);
percpu_ref_exit(pgmap->ref);
}
}
static void dev_pagemap_percpu_release(struct percpu_ref *ref)
{
struct dev_pagemap *pgmap =
container_of(ref, struct dev_pagemap, internal_ref);
complete(&pgmap->done);
}
void *__wrap_devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
{
int error;
resource_size_t offset = pgmap->res.start;
struct nfit_test_resource *nfit_res = get_nfit_res(offset);
if (nfit_res) {
int rc;
if (!nfit_res)
return devm_memremap_pages(dev, pgmap);
rc = devm_add_action_or_reset(dev, nfit_test_kill, pgmap);
if (rc)
return ERR_PTR(rc);
return nfit_res->buf + offset - nfit_res->res.start;
pgmap->dev = dev;
if (!pgmap->ref) {
if (pgmap->ops && (pgmap->ops->kill || pgmap->ops->cleanup))
return ERR_PTR(-EINVAL);
init_completion(&pgmap->done);
error = percpu_ref_init(&pgmap->internal_ref,
dev_pagemap_percpu_release, 0, GFP_KERNEL);
if (error)
return ERR_PTR(error);
pgmap->ref = &pgmap->internal_ref;
} else {
if (!pgmap->ops || !pgmap->ops->kill || !pgmap->ops->cleanup) {
WARN(1, "Missing reference count teardown definition\n");
return ERR_PTR(-EINVAL);
}
}
return devm_memremap_pages(dev, pgmap);
error = devm_add_action_or_reset(dev, nfit_test_kill, pgmap);
if (error)
return ERR_PTR(error);
return nfit_res->buf + offset - nfit_res->res.start;
}
EXPORT_SYMBOL_GPL(__wrap_devm_memremap_pages);