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lib/genalloc: introduce chunk owners

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The p2pdma facility enables a provider to publish a pool of dma
addresses for a consumer to allocate.  A genpool is used internally by
p2pdma to collect dma resources, 'chunks', to be handed out to
consumers.  Whenever a consumer allocates a resource it needs to pin the
'struct dev_pagemap' instance that backs the chunk selected by
pci_alloc_p2pmem().

Currently that reference is taken globally on the entire provider
device.  That sets up a lifetime mismatch whereby the p2pdma core needs
to maintain hacks to make sure the percpu_ref is not released twice.

This lifetime mismatch also stands in the way of a fix to
devm_memremap_pages() whereby devm_memremap_pages_release() must wait for
the percpu_ref ->release() callback to complete before it can proceed to
teardown pages.

So, towards fixing this situation, introduce the ability to store a 'chunk
owner' at gen_pool_add() time, and a facility to retrieve the owner at
gen_pool_{alloc,free}() time.  For p2pdma this will be used to store and
recall individual dev_pagemap reference counter instances per-chunk.

Link: http://lkml.kernel.org/r/155727338118.292046.13407378933221579644.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Williams 2019-06-13 15:56:27 -07:00 • committed by Linus Torvalds
parent e615a19121
commit 795ee30648
2 changed files with 74 additions and 32 deletions
Download patch file Download diff file Expand all files Collapse all files

55
include/linux/genalloc.h
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@ -75,6 +75,7 @@ struct gen_pool_chunk {
struct list_head next_chunk; /* next chunk in pool */
atomic_long_t avail;
phys_addr_t phys_addr; /* physical starting address of memory chunk */
void *owner; /* private data to retrieve at alloc time */
unsigned long start_addr; /* start address of memory chunk */
unsigned long end_addr; /* end address of memory chunk (inclusive) */
unsigned long bits[0]; /* bitmap for allocating memory chunk */
@ -96,8 +97,15 @@ struct genpool_data_fixed {
extern struct gen_pool *gen_pool_create(int, int);
extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
extern int gen_pool_add_virt(struct gen_pool *, unsigned long, phys_addr_t,
size_t, int);
extern int gen_pool_add_owner(struct gen_pool *, unsigned long, phys_addr_t,
size_t, int, void *);
static inline int gen_pool_add_virt(struct gen_pool *pool, unsigned long addr,
phys_addr_t phys, size_t size, int nid)
{
return gen_pool_add_owner(pool, addr, phys, size, nid, NULL);
}
/**
* gen_pool_add - add a new chunk of special memory to the pool
* @pool: pool to add new memory chunk to
@ -116,12 +124,47 @@ static inline int gen_pool_add(struct gen_pool *pool, unsigned long addr,
return gen_pool_add_virt(pool, addr, -1, size, nid);
}
extern void gen_pool_destroy(struct gen_pool *);
extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);
extern unsigned long gen_pool_alloc_algo(struct gen_pool *, size_t,
genpool_algo_t algo, void *data);
unsigned long gen_pool_alloc_algo_owner(struct gen_pool *pool, size_t size,
genpool_algo_t algo, void *data, void **owner);
static inline unsigned long gen_pool_alloc_owner(struct gen_pool *pool,
size_t size, void **owner)
{
return gen_pool_alloc_algo_owner(pool, size, pool->algo, pool->data,
owner);
}
static inline unsigned long gen_pool_alloc_algo(struct gen_pool *pool,
size_t size, genpool_algo_t algo, void *data)
{
return gen_pool_alloc_algo_owner(pool, size, algo, data, NULL);
}
/**
* gen_pool_alloc - allocate special memory from the pool
* @pool: pool to allocate from
* @size: number of bytes to allocate from the pool
*
* Allocate the requested number of bytes from the specified pool.
* Uses the pool allocation function (with first-fit algorithm by default).
* Can not be used in NMI handler on architectures without
* NMI-safe cmpxchg implementation.
*/
static inline unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
{
return gen_pool_alloc_algo(pool, size, pool->algo, pool->data);
}
extern void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size,
dma_addr_t *dma);
extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);
extern void gen_pool_free_owner(struct gen_pool *pool, unsigned long addr,
size_t size, void **owner);
static inline void gen_pool_free(struct gen_pool *pool, unsigned long addr,
size_t size)
{
gen_pool_free_owner(pool, addr, size, NULL);
}
extern void gen_pool_for_each_chunk(struct gen_pool *,
void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
extern size_t gen_pool_avail(struct gen_pool *);