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Sourcecode: fio version File versions

smalloc.c

/*
 * simple memory allocator, backed by mmap() so that it hands out memory
 * that can be shared across processes and threads
 */
#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <limits.h>

#include "mutex.h"
#include "arch/arch.h"

#define SMALLOC_REDZONE       /* define to detect memory corruption */

#define SMALLOC_BPB     32    /* block size, bytes-per-bit in bitmap */
#define SMALLOC_BPI     (sizeof(unsigned int) * 8)
#define SMALLOC_BPL     (SMALLOC_BPB * SMALLOC_BPI)

#define INITIAL_SIZE    8192*1024   /* new pool size */
#define MAX_POOLS 128         /* maximum number of pools to setup */

#define SMALLOC_PRE_RED       0xdeadbeefU
#define SMALLOC_POST_RED      0x5aa55aa5U

unsigned int smalloc_pool_size = INITIAL_SIZE;
const int int_mask = sizeof(int) - 1;

struct pool {
      struct fio_mutex *lock;             /* protects this pool */
      void *map;                    /* map of blocks */
      unsigned int *bitmap;               /* blocks free/busy map */
      unsigned int free_blocks;           /* free blocks */
      unsigned int nr_blocks;             /* total blocks */
      unsigned int next_non_full;
      int fd;                             /* memory backing fd */
      unsigned int mmap_size;
};

struct block_hdr {
      unsigned int size;
#ifdef SMALLOC_REDZONE
      unsigned int prered;
#endif
};

static struct pool mp[MAX_POOLS];
static unsigned int nr_pools;
static unsigned int last_pool;
static struct fio_mutex *lock;

static inline void pool_lock(struct pool *pool)
{
      fio_mutex_down(pool->lock);
}

static inline void pool_unlock(struct pool *pool)
{
      fio_mutex_up(pool->lock);
}

static inline void global_read_lock(void)
{
      fio_mutex_down_read(lock);
}

static inline void global_read_unlock(void)
{
      fio_mutex_up_read(lock);
}

static inline void global_write_lock(void)
{
      fio_mutex_down_write(lock);
}

static inline void global_write_unlock(void)
{
      fio_mutex_up_write(lock);
}

static inline int ptr_valid(struct pool *pool, void *ptr)
{
      unsigned int pool_size = pool->nr_blocks * SMALLOC_BPL;

      return (ptr >= pool->map) && (ptr < pool->map + pool_size);
}

static inline unsigned int size_to_blocks(unsigned int size)
{
      return (size + SMALLOC_BPB - 1) / SMALLOC_BPB;
}

static int blocks_iter(struct pool *pool, unsigned int pool_idx,
                   unsigned int idx, unsigned int nr_blocks,
                   int (*func)(unsigned int *map, unsigned int mask))
{

      while (nr_blocks) {
            unsigned int this_blocks, mask;
            unsigned int *map;

            if (pool_idx >= pool->nr_blocks)
                  return 0;

            map = &pool->bitmap[pool_idx];

            this_blocks = nr_blocks;
            if (this_blocks + idx > SMALLOC_BPI) {
                  this_blocks = SMALLOC_BPI - idx;
                  idx = SMALLOC_BPI - this_blocks;
            }

            if (this_blocks == SMALLOC_BPI)
                  mask = -1U;
            else
                  mask = ((1U << this_blocks) - 1) << idx;

            if (!func(map, mask))
                  return 0;

            nr_blocks -= this_blocks;
            idx = 0;
            pool_idx++;
      }

      return 1;
}

static int mask_cmp(unsigned int *map, unsigned int mask)
{
      return !(*map & mask);
}

static int mask_clear(unsigned int *map, unsigned int mask)
{
      assert((*map & mask) == mask);
      *map &= ~mask;
      return 1;
}

static int mask_set(unsigned int *map, unsigned int mask)
{
      assert(!(*map & mask));
      *map |= mask;
      return 1;
}

static int blocks_free(struct pool *pool, unsigned int pool_idx,
                   unsigned int idx, unsigned int nr_blocks)
{
      return blocks_iter(pool, pool_idx, idx, nr_blocks, mask_cmp);
}

static void set_blocks(struct pool *pool, unsigned int pool_idx,
                   unsigned int idx, unsigned int nr_blocks)
{
      blocks_iter(pool, pool_idx, idx, nr_blocks, mask_set);
}

static void clear_blocks(struct pool *pool, unsigned int pool_idx,
                   unsigned int idx, unsigned int nr_blocks)
{
      blocks_iter(pool, pool_idx, idx, nr_blocks, mask_clear);
}

static int find_next_zero(int word, int start)
{
      assert(word != -1U);
      word >>= (start + 1);
      return ffz(word) + start + 1;
}

static int add_pool(struct pool *pool, unsigned int alloc_size)
{
      int fd, bitmap_blocks;
      char file[] = "/tmp/.fio_smalloc.XXXXXX";
      void *ptr;

      fd = mkstemp(file);
      if (fd < 0)
            goto out_close;

#ifdef SMALLOC_REDZONE
      alloc_size += sizeof(unsigned int);
#endif
      alloc_size += sizeof(struct block_hdr);
      if (alloc_size < INITIAL_SIZE)
            alloc_size = INITIAL_SIZE;

      /* round up to nearest full number of blocks */
      alloc_size = (alloc_size + SMALLOC_BPL - 1) & ~(SMALLOC_BPL - 1);
      bitmap_blocks = alloc_size / SMALLOC_BPL;
      alloc_size += bitmap_blocks * sizeof(unsigned int);
      pool->mmap_size = alloc_size;
      
      pool->nr_blocks = bitmap_blocks;
      pool->free_blocks = bitmap_blocks * SMALLOC_BPB;

      if (ftruncate(fd, alloc_size) < 0)
            goto out_unlink;

      ptr = mmap(NULL, alloc_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
      if (ptr == MAP_FAILED)
            goto out_unlink;

      memset(ptr, 0, alloc_size);
      pool->map = ptr;
      pool->bitmap = (void *) ptr + (pool->nr_blocks * SMALLOC_BPL);

      pool->lock = fio_mutex_init(1);
      if (!pool->lock)
            goto out_unlink;

      /*
       * Unlink pool file now. It wont get deleted until the fd is closed,
       * which happens both for cleanup or unexpected quit. This way we
       * don't leave temp files around in case of a crash.
       */
      unlink(file);
      pool->fd = fd;

      nr_pools++;
      return 0;
out_unlink:
      fprintf(stderr, "smalloc: failed adding pool\n");
      if (pool->map)
            munmap(pool->map, pool->mmap_size);
      unlink(file);
out_close:
      close(fd);
      return 1;
}

void sinit(void)
{
      int ret;

      lock = fio_mutex_rw_init();
      ret = add_pool(&mp[0], INITIAL_SIZE);
      assert(!ret);
}

static void cleanup_pool(struct pool *pool)
{
      /*
       * This will also remove the temporary file we used as a backing
       * store, it was already unlinked
       */
      close(pool->fd);
      munmap(pool->map, pool->mmap_size);

      if (pool->lock)
            fio_mutex_remove(pool->lock);
}

void scleanup(void)
{
      unsigned int i;

      for (i = 0; i < nr_pools; i++)
            cleanup_pool(&mp[i]);

      if (lock)
            fio_mutex_remove(lock);
}

#ifdef SMALLOC_REDZONE
static void *postred_ptr(struct block_hdr *hdr)
{
      unsigned long ptr;

      ptr = (unsigned long) hdr + hdr->size - sizeof(unsigned int);
      ptr = (ptr + int_mask) & ~int_mask;

      return (void *) ptr;
}

static void fill_redzone(struct block_hdr *hdr)
{
      unsigned int *postred = postred_ptr(hdr);

      hdr->prered = SMALLOC_PRE_RED;
      *postred = SMALLOC_POST_RED;
}

static void sfree_check_redzone(struct block_hdr *hdr)
{
      unsigned int *postred = postred_ptr(hdr);

      if (hdr->prered != SMALLOC_PRE_RED) {
            fprintf(stderr, "smalloc pre redzone destroyed!\n");
            fprintf(stderr, "  ptr=%p, prered=%x, expected %x\n",
                        hdr, hdr->prered, SMALLOC_PRE_RED);
            assert(0);
      }
      if (*postred != SMALLOC_POST_RED) {
            fprintf(stderr, "smalloc post redzone destroyed!\n");
            fprintf(stderr, "  ptr=%p, postred=%x, expected %x\n",
                        hdr, *postred, SMALLOC_POST_RED);
            assert(0);
      }
}
#else
static void fill_redzone(struct block_hdr *hdr)
{
}

static void sfree_check_redzone(struct block_hdr *hdr)
{
}
#endif

static void sfree_pool(struct pool *pool, void *ptr)
{
      struct block_hdr *hdr;
      unsigned int i, idx;
      unsigned long offset;

      if (!ptr)
            return;

      ptr -= sizeof(*hdr);
      hdr = ptr;

      assert(ptr_valid(pool, ptr));

      sfree_check_redzone(hdr);

      offset = ptr - pool->map;
      i = offset / SMALLOC_BPL;
      idx = (offset % SMALLOC_BPL) / SMALLOC_BPB;

      pool_lock(pool);
      clear_blocks(pool, i, idx, size_to_blocks(hdr->size));
      if (i < pool->next_non_full)
            pool->next_non_full = i;
      pool->free_blocks += size_to_blocks(hdr->size);
      pool_unlock(pool);
}

void sfree(void *ptr)
{
      struct pool *pool = NULL;
      unsigned int i;

      if (!ptr)
            return;

      global_read_lock();

      for (i = 0; i < nr_pools; i++) {
            if (ptr_valid(&mp[i], ptr)) {
                  pool = &mp[i];
                  break;
            }
      }

      global_read_unlock();

      assert(pool);
      sfree_pool(pool, ptr);
}

static void *__smalloc_pool(struct pool *pool, unsigned int size)
{
      unsigned int nr_blocks;
      unsigned int i;
      unsigned int offset;
      unsigned int last_idx;
      void *ret = NULL;

      pool_lock(pool);

      nr_blocks = size_to_blocks(size);
      if (nr_blocks > pool->free_blocks)
            goto fail;

      i = pool->next_non_full;
      last_idx = 0;
      offset = -1U;
      while (i < pool->nr_blocks) {
            unsigned int idx;

            if (pool->bitmap[i] == -1U) {
                  i++;
                  pool->next_non_full = i;
                  last_idx = 0;
                  continue;
            }

            idx = find_next_zero(pool->bitmap[i], last_idx);
            if (!blocks_free(pool, i, idx, nr_blocks)) {
                  idx += nr_blocks;
                  if (idx < SMALLOC_BPI)
                        last_idx = idx;
                  else {
                        last_idx = 0;
                        while (idx >= SMALLOC_BPI) {
                              i++;
                              idx -= SMALLOC_BPI;
                        }
                  }
                  continue;
            }
            set_blocks(pool, i, idx, nr_blocks);
            offset = i * SMALLOC_BPL + idx * SMALLOC_BPB;
            break;
      }

      if (i < pool->nr_blocks) {
            pool->free_blocks -= nr_blocks;
            ret = pool->map + offset;
      }
fail:
      pool_unlock(pool);
      return ret;
}

static void *smalloc_pool(struct pool *pool, unsigned int size)
{
      unsigned int alloc_size = size + sizeof(struct block_hdr);
      void *ptr;

      /*
       * Round to int alignment, so that the postred pointer will
       * be naturally aligned as well.
       */
#ifdef SMALLOC_REDZONE
      alloc_size += sizeof(unsigned int);
      alloc_size = (alloc_size + int_mask) & ~int_mask;
#endif

      ptr = __smalloc_pool(pool, alloc_size);
      if (ptr) {
            struct block_hdr *hdr = ptr;

            hdr->size = alloc_size;
            fill_redzone(hdr);

            ptr += sizeof(*hdr);
            memset(ptr, 0, size);
      }

      return ptr;
}

void *smalloc(unsigned int size)
{
      unsigned int i;

      global_write_lock();
      i = last_pool;

      do {
            for (; i < nr_pools; i++) {
                  void *ptr = smalloc_pool(&mp[i], size);

                  if (ptr) {
                        last_pool = i;
                        global_write_unlock();
                        return ptr;
                  }
            }
            if (last_pool) {
                  last_pool = 0;
                  continue;
            }

            if (nr_pools + 1 > MAX_POOLS)
                  break;
            else {
                  i = nr_pools;
                  if (add_pool(&mp[nr_pools], size))
                        goto out;
            }
      } while (1);

out:
      global_write_unlock();
      return NULL;
}

char *smalloc_strdup(const char *str)
{
      char *ptr;

      ptr = smalloc(strlen(str) + 1);
      strcpy(ptr, str);
      return ptr;
}

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