From bea0ac1d8703091294fe5822d982591c849b5458 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 16 Jul 2009 07:24:50 -0700 Subject: [PATCH] Use rel semantics of cas instead of acq semantics with full barrier before it in _int_free The following patch fixes catomic_compare_and_exchange_*_rel definitions (which were never used and weren't correct) and uses catomic_compare_and_exchange_val_rel in _int_free. Comparing to the pre-2009-07-02 --enable-experimental-malloc state the generated code should be identical on all arches other than ppc/ppc64 and on ppc/ppc64 should use lwsync instead of isync barrier. --- ChangeLog | 13 +++++++++++++ include/atomic.h | 32 +++++++++++++++++++++----------- malloc/malloc.c | 3 +-- 3 files changed, 35 insertions(+), 13 deletions(-) diff --git a/ChangeLog b/ChangeLog index 48b5d02..1e9df42 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,16 @@ +2009-07-13 Jakub Jelinek + + * include/atomic.h (catomic_compare_and_exchange_val_rel): If arch + overrides atomic_compare_and_exchange_val_rel, define to + atomic_compare_and_exchange_val_rel by default, otherwise default + to catomic_compare_and_exchange_val_acq. + (catomic_compare_and_exchange_bool_rel): If arch overrides + atomic_compare_and_exchange_bool_rel, define to + atomic_compare_and_exchange_bool_rel by default. + * malloc/malloc.c (_int_free): Revert 2009-07-02 change. + Use catomic_compare_and_exchange_val_rel instead of + catomic_compare_and_exchange_val_acq. + 2009-07-16 Ulrich Drepper * sysdeps/generic/ldsodefs.h: Add prototype for diff --git a/include/atomic.h b/include/atomic.h index 9366f78..37d0111 100644 --- a/include/atomic.h +++ b/include/atomic.h @@ -107,14 +107,19 @@ #endif -#ifndef atomic_compare_and_exchange_val_rel -# define atomic_compare_and_exchange_val_rel(mem, newval, oldval) \ - atomic_compare_and_exchange_val_acq (mem, newval, oldval) +#ifndef catomic_compare_and_exchange_val_rel +# ifndef atomic_compare_and_exchange_val_rel +# define catomic_compare_and_exchange_val_rel(mem, newval, oldval) \ + catomic_compare_and_exchange_val_acq (mem, newval, oldval) +# else +# define catomic_compare_and_exchange_val_rel(mem, newval, oldval) \ + atomic_compare_and_exchange_val_rel (mem, newval, oldval) +# endif #endif -#ifndef catomic_compare_and_exchange_val_rel -# define catomic_compare_and_exchange_val_rel(mem, newval, oldval) \ +#ifndef atomic_compare_and_exchange_val_rel +# define atomic_compare_and_exchange_val_rel(mem, newval, oldval) \ atomic_compare_and_exchange_val_acq (mem, newval, oldval) #endif @@ -155,15 +160,20 @@ #endif -#ifndef atomic_compare_and_exchange_bool_rel -# define atomic_compare_and_exchange_bool_rel(mem, newval, oldval) \ - atomic_compare_and_exchange_bool_acq (mem, newval, oldval) +#ifndef catomic_compare_and_exchange_bool_rel +# ifndef atomic_compare_and_exchange_bool_rel +# define catomic_compare_and_exchange_bool_rel(mem, newval, oldval) \ + catomic_compare_and_exchange_bool_acq (mem, newval, oldval) +# else +# define catomic_compare_and_exchange_bool_rel(mem, newval, oldval) \ + atomic_compare_and_exchange_bool_rel (mem, newval, oldval) +# endif #endif -#ifndef catomic_compare_and_exchange_bool_rel -# define catomic_compare_and_exchange_bool_rel(mem, newval, oldval) \ - catomic_compare_and_exchange_bool_acq (mem, newval, oldval) +#ifndef atomic_compare_and_exchange_bool_rel +# define atomic_compare_and_exchange_bool_rel(mem, newval, oldval) \ + atomic_compare_and_exchange_bool_acq (mem, newval, oldval) #endif diff --git a/malloc/malloc.c b/malloc/malloc.c index 70e4e58..0c0182e 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -4822,9 +4822,8 @@ _int_free(mstate av, mchunkptr p) goto errout; } p->fd = fd = old; - atomic_full_barrier (); } - while ((old = catomic_compare_and_exchange_val_acq (fb, p, fd)) != fd); + while ((old = catomic_compare_and_exchange_val_rel (fb, p, fd)) != fd); #else /* Another simple check: make sure the top of the bin is not the record we are going to add (i.e., double free). */ -- 2.7.4