Commit cafe8816b217b98dc3f268d3b77445da498beb4f
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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: Tejun Heo <tj@kernel.org>
Showing 3 changed files with 29 additions and 24 deletions Side-by-side Diff
arch/x86/kernel/setup_percpu.c
... | ... | @@ -344,7 +344,7 @@ |
344 | 344 | pr_info("PERCPU: Allocated %d 4k pages, static data %zu bytes\n", |
345 | 345 | pcpu4k_nr_static_pages, static_size); |
346 | 346 | |
347 | - ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size, 0, 0, NULL, | |
347 | + ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size, -1, -1, NULL, | |
348 | 348 | pcpu4k_populate_pte); |
349 | 349 | goto out_free_ar; |
350 | 350 |
include/linux/percpu.h
... | ... | @@ -117,8 +117,9 @@ |
117 | 117 | typedef void (*pcpu_populate_pte_fn_t)(unsigned long addr); |
118 | 118 | |
119 | 119 | extern size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn, |
120 | - size_t static_size, size_t unit_size, | |
121 | - size_t dyn_size, void *base_addr, | |
120 | + size_t static_size, | |
121 | + ssize_t unit_size, ssize_t dyn_size, | |
122 | + void *base_addr, | |
122 | 123 | pcpu_populate_pte_fn_t populate_pte_fn); |
123 | 124 | |
124 | 125 | /* |
mm/percpu.c
... | ... | @@ -824,8 +824,8 @@ |
824 | 824 | * pcpu_setup_first_chunk - initialize the first percpu chunk |
825 | 825 | * @get_page_fn: callback to fetch page pointer |
826 | 826 | * @static_size: the size of static percpu area in bytes |
827 | - * @unit_size: unit size in bytes, must be multiple of PAGE_SIZE, 0 for auto | |
828 | - * @dyn_size: free size for dynamic allocation in bytes, 0 for auto | |
827 | + * @unit_size: unit size in bytes, must be multiple of PAGE_SIZE, -1 for auto | |
828 | + * @dyn_size: free size for dynamic allocation in bytes, -1 for auto | |
829 | 829 | * @base_addr: mapped address, NULL for auto |
830 | 830 | * @populate_pte_fn: callback to allocate pagetable, NULL if unnecessary |
831 | 831 | * |
832 | 832 | |
... | ... | @@ -842,13 +842,14 @@ |
842 | 842 | * indicates end of pages for the cpu. Note that @get_page_fn() must |
843 | 843 | * return the same number of pages for all cpus. |
844 | 844 | * |
845 | - * @unit_size, if non-zero, determines unit size and must be aligned | |
846 | - * to PAGE_SIZE and equal to or larger than @static_size + @dyn_size. | |
845 | + * @unit_size, if non-negative, specifies unit size and must be | |
846 | + * aligned to PAGE_SIZE and equal to or larger than @static_size + | |
847 | + * @dyn_size. | |
847 | 848 | * |
848 | - * @dyn_size determines the number of free bytes after the static | |
849 | - * area in the first chunk. If zero, whatever left is available. | |
850 | - * Specifying non-zero value make percpu leave the area after | |
851 | - * @static_size + @dyn_size alone. | |
849 | + * @dyn_size, if non-negative, limits the number of bytes available | |
850 | + * for dynamic allocation in the first chunk. Specifying non-negative | |
851 | + * value make percpu leave alone the area beyond @static_size + | |
852 | + * @dyn_size. | |
852 | 853 | * |
853 | 854 | * Non-null @base_addr means that the caller already allocated virtual |
854 | 855 | * region for the first chunk and mapped it. percpu must not mess |
... | ... | @@ -863,8 +864,9 @@ |
863 | 864 | * percpu access. |
864 | 865 | */ |
865 | 866 | size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn, |
866 | - size_t static_size, size_t unit_size, | |
867 | - size_t dyn_size, void *base_addr, | |
867 | + size_t static_size, | |
868 | + ssize_t unit_size, ssize_t dyn_size, | |
869 | + void *base_addr, | |
868 | 870 | pcpu_populate_pte_fn_t populate_pte_fn) |
869 | 871 | { |
870 | 872 | static struct vm_struct first_vm; |
871 | 873 | |
... | ... | @@ -877,13 +879,17 @@ |
877 | 879 | /* santiy checks */ |
878 | 880 | BUILD_BUG_ON(ARRAY_SIZE(smap) >= PCPU_DFL_MAP_ALLOC); |
879 | 881 | BUG_ON(!static_size); |
880 | - BUG_ON(!unit_size && dyn_size); | |
881 | - BUG_ON(unit_size && unit_size < static_size + dyn_size); | |
882 | - BUG_ON(unit_size & ~PAGE_MASK); | |
883 | - BUG_ON(base_addr && !unit_size); | |
882 | + if (unit_size >= 0) { | |
883 | + BUG_ON(unit_size < static_size + | |
884 | + (dyn_size >= 0 ? dyn_size : 0)); | |
885 | + BUG_ON(unit_size & ~PAGE_MASK); | |
886 | + } else { | |
887 | + BUG_ON(dyn_size >= 0); | |
888 | + BUG_ON(base_addr); | |
889 | + } | |
884 | 890 | BUG_ON(base_addr && populate_pte_fn); |
885 | 891 | |
886 | - if (unit_size) | |
892 | + if (unit_size >= 0) | |
887 | 893 | pcpu_unit_pages = unit_size >> PAGE_SHIFT; |
888 | 894 | else |
889 | 895 | pcpu_unit_pages = max_t(int, PCPU_MIN_UNIT_SIZE >> PAGE_SHIFT, |
... | ... | @@ -894,6 +900,9 @@ |
894 | 900 | pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) |
895 | 901 | + num_possible_cpus() * pcpu_unit_pages * sizeof(struct page *); |
896 | 902 | |
903 | + if (dyn_size < 0) | |
904 | + dyn_size = pcpu_unit_size - static_size; | |
905 | + | |
897 | 906 | /* |
898 | 907 | * Allocate chunk slots. The additional last slot is for |
899 | 908 | * empty chunks. |
... | ... | @@ -909,12 +918,7 @@ |
909 | 918 | schunk->vm = &first_vm; |
910 | 919 | schunk->map = smap; |
911 | 920 | schunk->map_alloc = ARRAY_SIZE(smap); |
912 | - | |
913 | - if (dyn_size) | |
914 | - schunk->free_size = dyn_size; | |
915 | - else | |
916 | - schunk->free_size = pcpu_unit_size - static_size; | |
917 | - | |
921 | + schunk->free_size = dyn_size; | |
918 | 922 | schunk->contig_hint = schunk->free_size; |
919 | 923 | |
920 | 924 | schunk->map[schunk->map_used++] = -static_size; |