percpu: add pcpu_unit_offsets[]

Currently units are mapped sequentially into address space.  This
patch adds pcpu_unit_offsets[] which allows units to be mapped to
arbitrary offsets from the chunk base address.  This is necessary to
allow sparse embedding which might would need to allocate address
ranges and memory areas which aren't aligned to unit size but
allocation atom size (page or large page size).  This also simplifies
things a bit by removing the need to calculate offset from unit
number.

With this change, there's no need for the arch code to know
pcpu_unit_size.  Update pcpu_setup_first_chunk() and first chunk
allocators to return regular 0 or -errno return code instead of unit
size or -errno.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 9 deletions

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 77b86be..a7ec840 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -57,7 +57,7 @@
 #endif
 
 extern void *pcpu_base_addr;
-extern const int *pcpu_unit_map;
+extern const unsigned long *pcpu_unit_offsets;
 
 struct pcpu_group_info {
 	int			nr_units;	/* aligned # of units */
@@ -106,25 +106,23 @@ extern struct pcpu_alloc_info * __init pcpu_build_alloc_info(
 				size_t atom_size,
 				pcpu_fc_cpu_distance_fn_t cpu_distance_fn);
 
-extern size_t __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
-					    void *base_addr);
+extern int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
+					 void *base_addr);
 
 #ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
-extern ssize_t __init pcpu_embed_first_chunk(
-				size_t reserved_size, ssize_t dyn_size);
+extern int __init pcpu_embed_first_chunk(size_t reserved_size,
+					 ssize_t dyn_size);
 #endif
 
 #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
-extern ssize_t __init pcpu_page_first_chunk(
-				size_t reserved_size,
+extern int __init pcpu_page_first_chunk(size_t reserved_size,
 				pcpu_fc_alloc_fn_t alloc_fn,
 				pcpu_fc_free_fn_t free_fn,
 				pcpu_fc_populate_pte_fn_t populate_pte_fn);
 #endif
 
 #ifdef CONFIG_NEED_PER_CPU_LPAGE_FIRST_CHUNK
-extern ssize_t __init pcpu_lpage_first_chunk(
-				const struct pcpu_alloc_info *ai,
+extern int __init pcpu_lpage_first_chunk(const struct pcpu_alloc_info *ai,
 				pcpu_fc_alloc_fn_t alloc_fn,
 				pcpu_fc_free_fn_t free_fn,
 				pcpu_fc_map_fn_t map_fn);