4e57b68178
I recently picked up my older work to remove unnecessary #includes of sched.h, starting from a patch by Dave Jones to not include sched.h from module.h. This reduces the number of indirect includes of sched.h by ~300. Another ~400 pointless direct includes can be removed after this disentangling (patch to follow later). However, quite a few indirect includes need to be fixed up for this. In order to feed the patches through -mm with as little disturbance as possible, I've split out the fixes I accumulated up to now (complete for i386 and x86_64, more archs to follow later) and post them before the real patch. This way this large part of the patch is kept simple with only adding #includes, and all hunks are independent of each other. So if any hunk rejects or gets in the way of other patches, just drop it. My scripts will pick it up again in the next round. Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
122 lines
2.4 KiB
C
122 lines
2.4 KiB
C
/*
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* A fast, small, non-recursive O(nlog n) sort for the Linux kernel
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*
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* Jan 23 2005 Matt Mackall <mpm@selenic.com>
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/sort.h>
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#include <linux/slab.h>
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static void u32_swap(void *a, void *b, int size)
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{
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u32 t = *(u32 *)a;
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*(u32 *)a = *(u32 *)b;
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*(u32 *)b = t;
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}
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static void generic_swap(void *a, void *b, int size)
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{
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char t;
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do {
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t = *(char *)a;
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*(char *)a++ = *(char *)b;
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*(char *)b++ = t;
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} while (--size > 0);
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}
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/*
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* sort - sort an array of elements
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* @base: pointer to data to sort
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* @num: number of elements
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* @size: size of each element
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* @cmp: pointer to comparison function
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* @swap: pointer to swap function or NULL
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*
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* This function does a heapsort on the given array. You may provide a
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* swap function optimized to your element type.
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*
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* Sorting time is O(n log n) both on average and worst-case. While
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* qsort is about 20% faster on average, it suffers from exploitable
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* O(n*n) worst-case behavior and extra memory requirements that make
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* it less suitable for kernel use.
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*/
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void sort(void *base, size_t num, size_t size,
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int (*cmp)(const void *, const void *),
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void (*swap)(void *, void *, int size))
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{
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/* pre-scale counters for performance */
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int i = (num/2) * size, n = num * size, c, r;
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if (!swap)
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swap = (size == 4 ? u32_swap : generic_swap);
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/* heapify */
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for ( ; i >= 0; i -= size) {
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for (r = i; r * 2 < n; r = c) {
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c = r * 2;
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if (c < n - size && cmp(base + c, base + c + size) < 0)
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c += size;
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if (cmp(base + r, base + c) >= 0)
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break;
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swap(base + r, base + c, size);
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}
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}
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/* sort */
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for (i = n - size; i >= 0; i -= size) {
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swap(base, base + i, size);
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for (r = 0; r * 2 < i; r = c) {
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c = r * 2;
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if (c < i - size && cmp(base + c, base + c + size) < 0)
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c += size;
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if (cmp(base + r, base + c) >= 0)
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break;
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swap(base + r, base + c, size);
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}
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}
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}
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EXPORT_SYMBOL(sort);
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#if 0
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/* a simple boot-time regression test */
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int cmpint(const void *a, const void *b)
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{
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return *(int *)a - *(int *)b;
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}
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static int sort_test(void)
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{
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int *a, i, r = 1;
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a = kmalloc(1000 * sizeof(int), GFP_KERNEL);
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BUG_ON(!a);
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printk("testing sort()\n");
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for (i = 0; i < 1000; i++) {
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r = (r * 725861) % 6599;
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a[i] = r;
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}
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sort(a, 1000, sizeof(int), cmpint, NULL);
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for (i = 0; i < 999; i++)
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if (a[i] > a[i+1]) {
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printk("sort() failed!\n");
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break;
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}
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kfree(a);
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return 0;
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}
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module_init(sort_test);
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#endif
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