diff options
Diffstat (limited to 'malloc/malloc.c')
| -rw-r--r-- | malloc/malloc.c | 166 |
1 files changed, 70 insertions, 96 deletions
diff --git a/malloc/malloc.c b/malloc/malloc.c index 1908956ed1..feaf7ee0bf 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -1316,78 +1316,6 @@ nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ #define set_foot(p, s) (((mchunkptr) ((char *) (p) + (s)))->mchunk_prev_size = (s)) -/* Add an item to the atomic fastbin list at *ROOT. Returns the old - value at *ROOT. Note that properties of the old chunk are only - stable if the caller has acquired the arena lock. With out the - lock, it can be deallocated at any time. */ -static inline struct malloc_chunk * -fastbin_push_entry (struct malloc_chunk **root, struct malloc_chunk *e) -{ - struct malloc_chunk *head; - if (SINGLE_THREAD_P) - { - /* Check that the top of the bin is not the record we are going - to add (i.e., double free). */ - head = *root; - if (head == e) - malloc_printerr ("double free or corruption (fasttop)"); - e->fd = head; - *root = e; - } - else - do - { - /* Synchronize with the release release MO CAS below. We do - not need synchronization locally, but fastbin_pop_entry and - (especially) malloc_consolidate read the entire list after - synchronizing on the head, so we need to make sure that the - writes to the next (fd) pointers have happened. */ - head = atomic_load_acquire (root); - /* Check that the top of the bin is not the record we are - going to add (i.e., double free). */ - if (head == e) - malloc_printerr ("double free or corruption (fasttop)"); - e->fd = head; - } - /* Synchronizes with the acquire MO CAS in */ - while (!atomic_compare_exchange_weak_release (root, &head, e)); - return head; -} - -/* Remove an item from the atomic fastbin list at *ROOT. The caller - must have acquired the arena lock. */ -static inline struct malloc_chunk * -fastbin_pop_entry (struct malloc_chunk **root) -{ - struct malloc_chunk *head; - if (SINGLE_THREAD_P) - { - head = *root; - if (head != NULL) - *root = head->fd; - } - else - { - /* Synchromizes with the release MO store in fastbin_push_entry. - Synchronization is needed because we read the next list - pointer. */ - head = atomic_load_acquire (root); - struct malloc_chunk *tail; - do - { - if (head == NULL) - return NULL; - tail = head->fd; - } - /* Synchronizes with the release MO store in fastbin_push_entry. - We do not have an ABA issue here because the caller has - acquired the arena lock, which ensures that there is only one - thread which removes elements from this list. */ - while (!atomic_compare_exchange_weak_acquire (root, &head, tail)); - } - return head; -} - #pragma GCC poison mchunk_size #pragma GCC poison mchunk_prev_size @@ -3648,36 +3576,63 @@ _int_malloc (mstate av, size_t bytes) can try it without checking, which saves some time on this fast path. */ +#define REMOVE_FB(fb, victim, pp) \ + do \ + { \ + victim = pp; \ + if (victim == NULL) \ + break; \ + } \ + while ((pp = catomic_compare_and_exchange_val_acq (fb, victim->fd, victim)) \ + != victim); \ + if ((unsigned long) (nb) <= (unsigned long) (get_max_fast ())) { idx = fastbin_index (nb); mfastbinptr *fb = &fastbin (av, idx); - victim = fastbin_pop_entry (fb); + mchunkptr pp; + victim = *fb; + if (victim != NULL) { - size_t victim_idx = fastbin_index (chunksize (victim)); - if (victim_idx != idx) - malloc_printerr ("malloc(): memory corruption (fast)"); - check_remalloced_chunk (av, victim, nb); -#if USE_TCACHE - /* While we're here, if we see other chunks of the same size, - stash them in the tcache. */ - size_t tc_idx = csize2tidx (nb); - if (tcache && tc_idx < mp_.tcache_bins) + if (SINGLE_THREAD_P) + *fb = victim->fd; + else + REMOVE_FB (fb, pp, victim); + if (__glibc_likely (victim != NULL)) { - /* While bin not empty and tcache not full, copy chunks. */ - while (tcache->counts[tc_idx] < mp_.tcache_count) + size_t victim_idx = fastbin_index (chunksize (victim)); + if (__builtin_expect (victim_idx != idx, 0)) + malloc_printerr ("malloc(): memory corruption (fast)"); + check_remalloced_chunk (av, victim, nb); +#if USE_TCACHE + /* While we're here, if we see other chunks of the same size, + stash them in the tcache. */ + size_t tc_idx = csize2tidx (nb); + if (tcache && tc_idx < mp_.tcache_bins) { - mchunkptr tc_victim = fastbin_pop_entry (fb); - if (tc_victim == NULL) - break; - tcache_put (tc_victim, tc_idx); + mchunkptr tc_victim; + + /* While bin not empty and tcache not full, copy chunks. */ + while (tcache->counts[tc_idx] < mp_.tcache_count + && (tc_victim = *fb) != NULL) + { + if (SINGLE_THREAD_P) + *fb = tc_victim->fd; + else + { + REMOVE_FB (fb, pp, tc_victim); + if (__glibc_unlikely (tc_victim == NULL)) + break; + } + tcache_put (tc_victim, tc_idx); + } } - } #endif - void *p = chunk2mem (victim); - alloc_perturb (p, bytes); - return p; + void *p = chunk2mem (victim); + alloc_perturb (p, bytes); + return p; + } } } @@ -4309,7 +4264,28 @@ _int_free (mstate av, mchunkptr p, int have_lock) fb = &fastbin (av, idx); /* Atomically link P to its fastbin: P->FD = *FB; *FB = P; */ - mchunkptr old = fastbin_push_entry (fb, p); + mchunkptr old = *fb, old2; + + if (SINGLE_THREAD_P) + { + /* Check that the top of the bin is not the record we are going to + add (i.e., double free). */ + if (__builtin_expect (old == p, 0)) + malloc_printerr ("double free or corruption (fasttop)"); + p->fd = old; + *fb = p; + } + else + do + { + /* Check that the top of the bin is not the record we are going to + add (i.e., double free). */ + if (__builtin_expect (old == p, 0)) + malloc_printerr ("double free or corruption (fasttop)"); + p->fd = old2 = old; + } + while ((old = catomic_compare_and_exchange_val_rel (fb, p, old2)) + != old2); /* Check that size of fastbin chunk at the top is the same as size of the chunk that we are adding. We can dereference OLD @@ -4500,9 +4476,7 @@ static void malloc_consolidate(mstate av) maxfb = &fastbin (av, NFASTBINS - 1); fb = &fastbin (av, 0); do { - /* Synchronizes with the release MO store in - fastbin_push_entry. */ - p = atomic_exchange_acquire (fb, NULL); + p = atomic_exchange_acq (fb, NULL); if (p != 0) { do { { |