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Commit 6074d5b0 authored by Tejun Heo's avatar Tejun Heo
Browse files

percpu: more flexibility for @dyn_size of pcpu_setup_first_chunk() 



Impact: cleanup, more flexibility for first chunk init

Non-negative @dyn_size used to be allowed iff @unit_size wasn't auto.
This restriction stemmed from implementation detail and made things a
bit less intuitive.  This patch allows @dyn_size to be specified
regardless of @unit_size and swaps the positions of @dyn_size and
@unit_size so that the parameter order makes more sense (static,
reserved and dyn sizes followed by enclosing unit_size).

While at it, add @unit_size >= PCPU_MIN_UNIT_SIZE sanity check.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent e0100983

arch/x86/kernel/setup_percpu.c

+6 −7
Original line number Diff line number Diff line
@@ -233,8 +233,8 @@ proceed: 
		"%zu bytes\n", vm.addr, static_size);



	ret = pcpu_setup_first_chunk(pcpur_get_page, static_size,

				     PERCPU_FIRST_CHUNK_RESERVE,

				     PMD_SIZE, dyn_size, vm.addr, NULL);

				     PERCPU_FIRST_CHUNK_RESERVE, dyn_size,

				     PMD_SIZE, vm.addr, NULL);

	goto out_free_ar;



enomem:
@@ -315,9 +315,8 @@ static ssize_t __init setup_pcpu_embed(size_t static_size) 
		pcpue_size >> PAGE_SHIFT, pcpue_ptr, static_size);



	return pcpu_setup_first_chunk(pcpue_get_page, static_size,

				      PERCPU_FIRST_CHUNK_RESERVE,

				      pcpue_unit_size, dyn_size,

				      pcpue_ptr, NULL);

				      PERCPU_FIRST_CHUNK_RESERVE, dyn_size,

				      pcpue_unit_size, pcpue_ptr, NULL);

}



/*
@@ -375,8 +374,8 @@ static ssize_t __init setup_pcpu_4k(size_t static_size) 
		pcpu4k_nr_static_pages, static_size);



	ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size,

				     PERCPU_FIRST_CHUNK_RESERVE, -1, -1, NULL,

				     pcpu4k_populate_pte);

				     PERCPU_FIRST_CHUNK_RESERVE, -1,

				     -1, NULL, pcpu4k_populate_pte);

	goto out_free_ar;



enomem:

include/linux/percpu.h

+1 −1
Original line number Diff line number Diff line
@@ -107,7 +107,7 @@ typedef void (*pcpu_populate_pte_fn_t)(unsigned long addr); 


extern size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,

				size_t static_size, size_t reserved_size,

				ssize_t unit_size, ssize_t dyn_size,

				ssize_t dyn_size, ssize_t unit_size,

				void *base_addr,

				pcpu_populate_pte_fn_t populate_pte_fn);

mm/percpu.c

+14 −14
Original line number Diff line number Diff line
@@ -1027,8 +1027,8 @@ EXPORT_SYMBOL_GPL(free_percpu); 
 * @get_page_fn: callback to fetch page pointer

 * @static_size: the size of static percpu area in bytes

 * @reserved_size: the size of reserved percpu area in bytes

 * @unit_size: unit size in bytes, must be multiple of PAGE_SIZE, -1 for auto

 * @dyn_size: free size for dynamic allocation in bytes, -1 for auto

 * @unit_size: unit size in bytes, must be multiple of PAGE_SIZE, -1 for auto

 * @base_addr: mapped address, NULL for auto

 * @populate_pte_fn: callback to allocate pagetable, NULL if unnecessary

 *
@@ -1053,14 +1053,14 @@ EXPORT_SYMBOL_GPL(free_percpu); 
 * limited offset range for symbol relocations to guarantee module

 * percpu symbols fall inside the relocatable range.

 *

 * @dyn_size, if non-negative, determines the number of bytes

 * available for dynamic allocation in the first chunk.  Specifying

 * non-negative value makes percpu leave alone the area beyond

 * @static_size + @reserved_size + @dyn_size.

 *

 * @unit_size, if non-negative, specifies unit size and must be

 * aligned to PAGE_SIZE and equal to or larger than @static_size +

 * @reserved_size + @dyn_size.

 *

 * @dyn_size, if non-negative, limits the number of bytes available

 * for dynamic allocation in the first chunk.  Specifying non-negative

 * value make percpu leave alone the area beyond @static_size +

 * @reserved_size + @dyn_size.

 * @reserved_size + if non-negative, @dyn_size.

 *

 * Non-null @base_addr means that the caller already allocated virtual

 * region for the first chunk and mapped it.  percpu must not mess
@@ -1083,12 +1083,14 @@ EXPORT_SYMBOL_GPL(free_percpu); 
 */

size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,

				     size_t static_size, size_t reserved_size,

				     ssize_t unit_size, ssize_t dyn_size,

				     ssize_t dyn_size, ssize_t unit_size,

				     void *base_addr,

				     pcpu_populate_pte_fn_t populate_pte_fn)

{

	static struct vm_struct first_vm;

	static int smap[2], dmap[2];

	size_t size_sum = static_size + reserved_size +

			  (dyn_size >= 0 ? dyn_size : 0);

	struct pcpu_chunk *schunk, *dchunk = NULL;

	unsigned int cpu;

	int nr_pages;
@@ -1099,20 +1101,18 @@ size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn, 
		     ARRAY_SIZE(dmap) >= PCPU_DFL_MAP_ALLOC);

	BUG_ON(!static_size);

	if (unit_size >= 0) {

		BUG_ON(unit_size < static_size + reserved_size +

				   (dyn_size >= 0 ? dyn_size : 0));

		BUG_ON(unit_size < size_sum);

		BUG_ON(unit_size & ~PAGE_MASK);

	} else {

		BUG_ON(dyn_size >= 0);

		BUG_ON(unit_size < PCPU_MIN_UNIT_SIZE);

	} else

		BUG_ON(base_addr);

	}

	BUG_ON(base_addr && populate_pte_fn);



	if (unit_size >= 0)

		pcpu_unit_pages = unit_size >> PAGE_SHIFT;

	else

		pcpu_unit_pages = max_t(int, PCPU_MIN_UNIT_SIZE >> PAGE_SHIFT,

					PFN_UP(static_size + reserved_size));

					PFN_UP(size_sum));



	pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;

	pcpu_chunk_size = num_possible_cpus() * pcpu_unit_size;