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Commit cafe8816 authored by Tejun Heo's avatar Tejun Heo
Browse files

percpu: use negative for auto for pcpu_setup_first_chunk() arguments 



Impact: argument semantic cleanup

In pcpu_setup_first_chunk(), zero @unit_size and @dyn_size meant
auto-sizing.  It's okay for @unit_size as 0 doesn't make sense but 0
dynamic reserve size is valid.  Alos, if arch @dyn_size is calculated
from other parameters, it might end up passing in 0 @dyn_size and
malfunction when the size is automatically adjusted.

This patch makes both @unit_size and @dyn_size ssize_t and use -1 for
auto sizing.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 61ace7fa

arch/x86/kernel/setup_percpu.c

+1 −1
Original line number Diff line number Diff line
@@ -344,7 +344,7 @@ static ssize_t __init setup_pcpu_4k(size_t static_size) 
	pr_info("PERCPU: Allocated %d 4k pages, static data %zu bytes\n",

		pcpu4k_nr_static_pages, static_size);



	ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size, 0, 0, NULL,

	ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size, -1, -1, NULL,

				     pcpu4k_populate_pte);

	goto out_free_ar;

include/linux/percpu.h

+3 −2
Original line number Diff line number Diff line
@@ -117,8 +117,9 @@ typedef struct page * (*pcpu_get_page_fn_t)(unsigned int cpu, int pageno); 
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 unit_size,

					size_t dyn_size, void *base_addr,

					size_t static_size,

					ssize_t unit_size, ssize_t dyn_size,

					void *base_addr,

					pcpu_populate_pte_fn_t populate_pte_fn);



/*

mm/percpu.c

+25 −21
Original line number Diff line number Diff line
@@ -824,8 +824,8 @@ EXPORT_SYMBOL_GPL(free_percpu); 
 * pcpu_setup_first_chunk - initialize the first percpu chunk

 * @get_page_fn: callback to fetch page pointer

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

 * @unit_size: unit size in bytes, must be multiple of PAGE_SIZE, 0 for auto

 * @dyn_size: free size for dynamic allocation in bytes, 0 for auto

 * @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

 * @base_addr: mapped address, NULL for auto

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

 *
@@ -842,13 +842,14 @@ EXPORT_SYMBOL_GPL(free_percpu); 
 * indicates end of pages for the cpu.  Note that @get_page_fn() must

 * return the same number of pages for all cpus.

 *

 * @unit_size, if non-zero, determines unit size and must be aligned

 * to PAGE_SIZE and equal to or larger than @static_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 +

 * @dyn_size.

 *

 * @dyn_size determines the number of free bytes after the static

 * area in the first chunk.  If zero, whatever left is available.

 * Specifying non-zero value make percpu leave the area after

 * @static_size + @dyn_size alone.

 * @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 +

 * @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
@@ -863,8 +864,9 @@ EXPORT_SYMBOL_GPL(free_percpu); 
 * percpu access.

 */

size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,

				     size_t static_size, size_t unit_size,

				     size_t dyn_size, void *base_addr,

				     size_t static_size,

				     ssize_t unit_size, ssize_t dyn_size,

				     void *base_addr,

				     pcpu_populate_pte_fn_t populate_pte_fn)

{

	static struct vm_struct first_vm;
@@ -877,13 +879,17 @@ size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn, 
	/* santiy checks */

	BUILD_BUG_ON(ARRAY_SIZE(smap) >= PCPU_DFL_MAP_ALLOC);

	BUG_ON(!static_size);

	BUG_ON(!unit_size && dyn_size);

	BUG_ON(unit_size && unit_size < static_size + dyn_size);

	if (unit_size >= 0) {

		BUG_ON(unit_size < static_size +

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

		BUG_ON(unit_size & ~PAGE_MASK);

	BUG_ON(base_addr && !unit_size);

	} else {

		BUG_ON(dyn_size >= 0);

		BUG_ON(base_addr);

	}

	BUG_ON(base_addr && populate_pte_fn);



	if (unit_size)

	if (unit_size >= 0)

		pcpu_unit_pages = unit_size >> PAGE_SHIFT;

	else

		pcpu_unit_pages = max_t(int, PCPU_MIN_UNIT_SIZE >> PAGE_SHIFT,
@@ -894,6 +900,9 @@ size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn, 
	pcpu_chunk_struct_size = sizeof(struct pcpu_chunk)

		+ num_possible_cpus() * pcpu_unit_pages * sizeof(struct page *);



	if (dyn_size < 0)

		dyn_size = pcpu_unit_size - static_size;



	/*

	 * Allocate chunk slots.  The additional last slot is for

	 * empty chunks.
@@ -909,12 +918,7 @@ size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn, 
	schunk->vm = &first_vm;

	schunk->map = smap;

	schunk->map_alloc = ARRAY_SIZE(smap);



	if (dyn_size)

	schunk->free_size = dyn_size;

	else

		schunk->free_size = pcpu_unit_size - static_size;



	schunk->contig_hint = schunk->free_size;



	schunk->map[schunk->map_used++] = -static_size;