223 lines
5.8 KiB
C
223 lines
5.8 KiB
C
/*
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* Copyright (c) 2014, Steffen Vogel, RWTH Aachen University
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* @author Steffen Vogel <steffen.vogel@rwth-aachen.de>
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*/
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#include <eduos/stdio.h>
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#include <eduos/malloc.h>
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#include <eduos/spinlock.h>
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#include <eduos/memory.h>
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#include <asm/page.h>
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/// A linked list for each binary size exponent
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static buddy_t* buddy_lists[BUDDY_LISTS] = { [0 ... BUDDY_LISTS-1] = NULL };
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/// Lock for the buddy lists
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static spinlock_t buddy_lock = SPINLOCK_INIT;
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/** @brief Check if larger free buddies are available */
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static inline int buddy_large_avail(uint8_t exp)
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{
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while (exp<BUDDY_MAX && !buddy_lists[exp-BUDDY_MIN])
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exp++;
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return exp != BUDDY_MAX;
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}
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/** @brief Calculate the required buddy size */
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static inline int buddy_exp(size_t sz)
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{
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int exp;
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for (exp=0; sz>(1<<exp); exp++);
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if (exp > BUDDY_MAX)
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exp = 0;
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if (exp < BUDDY_MIN)
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exp = BUDDY_MIN;
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return exp;
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}
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/** @brief Get a free buddy by potentially splitting a larger one */
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static buddy_t* buddy_get(int exp)
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{
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spinlock_lock(&buddy_lock);
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buddy_t** list = &buddy_lists[exp-BUDDY_MIN];
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buddy_t* buddy = *list;
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buddy_t* split;
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if (buddy)
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// there is already a free buddy =>
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// we remove it from the list
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*list = buddy->next;
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else if (exp >= BUDDY_ALLOC && !buddy_large_avail(exp))
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// theres no free buddy larger than exp =>
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// we can allocate new memory
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buddy = (buddy_t*) palloc(1<<exp, 0);
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else {
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// we recursivly request a larger buddy...
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buddy = buddy_get(exp+1);
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if (BUILTIN_EXPECT(!buddy, 0))
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goto out;
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// ... and split it, by putting the second half back to the list
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split = (buddy_t*) ((size_t) buddy + (1<<exp));
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split->next = *list;
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*list = split;
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}
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out:
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spinlock_unlock(&buddy_lock);
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return buddy;
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}
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/** @brief Put a buddy back to its free list
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*
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* TODO: merge adjacent buddies (memory compaction)
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*/
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static void buddy_put(buddy_t* buddy)
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{
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spinlock_lock(&buddy_lock);
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buddy_t** list = &buddy_lists[buddy->prefix.exponent-BUDDY_MIN];
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buddy->next = *list;
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*list = buddy;
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spinlock_unlock(&buddy_lock);
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}
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void buddy_dump(void)
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{
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size_t free = 0;
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int i;
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for (i=0; i<BUDDY_LISTS; i++) {
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buddy_t* buddy;
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int exp = i+BUDDY_MIN;
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if (buddy_lists[i])
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kprintf("buddy_list[%u] (exp=%u, size=%lu bytes):\n", i, exp, 1<<exp);
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for (buddy=buddy_lists[i]; buddy; buddy=buddy->next) {
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kprintf(" %p -> %p \n", buddy, buddy->next);
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free += 1<<exp;
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}
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}
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kprintf("free buddies: %lu bytes\n", free);
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}
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void* palloc(size_t sz, uint32_t flags)
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{
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size_t phyaddr, viraddr;
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uint32_t npages = PAGE_FLOOR(sz) >> PAGE_BITS;
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int err;
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//kprintf("palloc(%lu) (%lu pages)\n", sz, npages);
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// get free virtual address space
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viraddr = vma_alloc(npages*PAGE_SIZE, VMA_HEAP);
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if (BUILTIN_EXPECT(!viraddr, 0))
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return NULL;
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// get continous physical pages
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phyaddr = get_pages(npages);
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if (BUILTIN_EXPECT(!phyaddr, 0)) {
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vma_free(viraddr, viraddr+npages*PAGE_SIZE);
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return NULL;
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}
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// map physical pages to VMA
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err = page_map(viraddr, phyaddr, npages, PG_RW|PG_GLOBAL);
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if (BUILTIN_EXPECT(err, 0)) {
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vma_free(viraddr, viraddr+npages*PAGE_SIZE);
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put_pages(phyaddr, npages);
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return NULL;
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}
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return (void*) viraddr;
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}
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void pfree(void* addr, size_t sz)
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{
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if (BUILTIN_EXPECT(!addr || !sz, 0))
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return;
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size_t i;
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size_t phyaddr;
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size_t viraddr = (size_t) addr & PAGE_MASK;
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uint32_t npages = PAGE_FLOOR(sz) >> PAGE_BITS;
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// memory is probably not continuously mapped! (userspace heap)
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for (i=0; i<npages; i++) {
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phyaddr = virt_to_phys(viraddr+i*PAGE_SIZE);
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put_page(phyaddr);
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}
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page_unmap(viraddr, npages);
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vma_free(viraddr, viraddr+npages*PAGE_SIZE);
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}
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void* kmalloc(size_t sz)
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{
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if (BUILTIN_EXPECT(!sz, 0))
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return NULL;
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// add space for the prefix
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sz += sizeof(buddy_t);
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int exp = buddy_exp(sz);
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if (BUILTIN_EXPECT(!exp, 0))
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return NULL;
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buddy_t* buddy = buddy_get(exp);
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if (BUILTIN_EXPECT(!buddy, 0))
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return NULL;
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// setup buddy prefix
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buddy->prefix.magic = BUDDY_MAGIC;
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buddy->prefix.exponent = exp;
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//kprintf("kmalloc(%lu) = %p\n", sz, buddy+1);
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// pointer arithmetic: we hide the prefix
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return buddy+1;
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}
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void kfree(void *addr)
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{
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if (BUILTIN_EXPECT(!addr, 0))
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return;
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//kprintf("kfree(%lu)\n", addr);
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buddy_t* buddy = (buddy_t*) addr - 1; // get prefix
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// check magic
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if (BUILTIN_EXPECT(buddy->prefix.magic != BUDDY_MAGIC, 0))
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return;
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buddy_put(buddy);
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}
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