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https://gitlab.nic.cz/labs/bird.git
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a95141111c
The original algorithm was suffering from an ABA race condition: A: fp = page_stack B: completely allocates the same page and writes into it some data A: unsuspecting, loads (invalid) next = fp->next B: finishes working with the page and returns it back to page_stack A: compare-exchange page_stack: fp => next succeeds and writes garbage to page_stack Fixed this by using an implicit spinlock in hot page allocator.
75 lines
1.4 KiB
C
75 lines
1.4 KiB
C
/*
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* BIRD -- Allocator Tests
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*
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* (c) 2023 CZ.NIC z.s.p.o.
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* (c) 2023 Maria Matejka <mq@jmq.cz>
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*
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* Can be freely distributed and used under the terms of the GNU GPL.
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*/
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#include "test/birdtest.h"
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#include "test/bt-utils.h"
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#include "lib/resource.h"
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#include <unistd.h>
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#include <pthread.h>
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#define ALLOC_AND_TREE_LIMIT (1 << 14)
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static void *
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alloc_and_free_main(void *data UNUSED)
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{
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#define BLOCK_SIZE 32
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void *block[BLOCK_SIZE];
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for (int i=0; i<ALLOC_AND_TREE_LIMIT; i++)
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{
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for (int b=0; b<BLOCK_SIZE; b++)
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{
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block[b] = alloc_page();
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ASSERT_DIE(PAGE_HEAD(block[b]) == block[b]);
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memset(block[b], 0x42, page_size);
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}
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for (int b=0; b<BLOCK_SIZE; b++)
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{
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free_page(block[b]);
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block[b] = alloc_page();
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ASSERT_DIE(PAGE_HEAD(block[b]) == block[b]);
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memset(block[b], 0x53, page_size);
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}
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for (int b=0; b<BLOCK_SIZE; b++)
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free_page(block[b]);
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}
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return NULL;
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}
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static int
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t_alloc_and_free(void)
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{
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#define THR_N 16
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pthread_t tid[THR_N];
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for (int i=0; i<THR_N; i++)
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{
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pthread_create(&tid[i], NULL, alloc_and_free_main, NULL);
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usleep(50 * i);
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}
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for (int i=0; i<THR_N; i++)
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pthread_join(tid[i], NULL);
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return 1;
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}
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int main(int argc, char **argv)
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{
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bt_init(argc, argv);
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bt_test_suite(t_alloc_and_free, "Testing parallel allocations and free");
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return bt_exit_value();
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}
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