diff options
| -rw-r--r-- | ChangeLog | 4 | ||||
| -rw-r--r-- | malloc/malloc.c | 43 |
2 files changed, 33 insertions, 14 deletions
@@ -1,3 +1,7 @@ +2017-10-20 Wilco Dijkstra <wdijkstr@arm.com> + + * malloc/malloc.c (_int_free): Add SINGLE_THREAD_P fast paths. + 2017-10-20 Will Hawkins <hawkinsw@borlaugic.com> * resolv/Makefile [$(build-shared)$(have-thread-library) == yesyes] diff --git a/malloc/malloc.c b/malloc/malloc.c index 3d7c239..4db21cc 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -4159,24 +4159,34 @@ _int_free (mstate av, mchunkptr p, int have_lock) /* Atomically link P to its fastbin: P->FD = *FB; *FB = P; */ mchunkptr old = *fb, old2; - unsigned int old_idx = ~0u; - do + + if (SINGLE_THREAD_P) { - /* Check that the top of the bin is not the record we are going to add - (i.e., double free). */ + /* 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)"); - /* 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 - only if we have the lock, otherwise it might have already been - deallocated. See use of OLD_IDX below for the actual check. */ - if (have_lock && old != NULL) - old_idx = fastbin_index(chunksize(old)); - p->fd = old2 = old; + p->fd = old; + *fb = p; } - while ((old = catomic_compare_and_exchange_val_rel (fb, p, old2)) != old2); - - if (have_lock && old != NULL && __builtin_expect (old_idx != idx, 0)) + 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 + only if we have the lock, otherwise it might have already been + allocated again. */ + if (have_lock && old != NULL + && __builtin_expect (fastbin_index (chunksize (old)) != idx, 0)) malloc_printerr ("invalid fastbin entry (free)"); } @@ -4185,6 +4195,11 @@ _int_free (mstate av, mchunkptr p, int have_lock) */ else if (!chunk_is_mmapped(p)) { + + /* If we're single-threaded, don't lock the arena. */ + if (SINGLE_THREAD_P) + have_lock = true; + if (!have_lock) __libc_lock_lock (av->mutex); |