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authorJakub Jelinek <jakub@redhat.com>2009-07-16 07:24:50 -0700
committerUlrich Drepper <drepper@redhat.com>2009-07-16 07:24:50 -0700
commitbea0ac1d8703091294fe5822d982591c849b5458 (patch)
tree1d7b20d187c218c9113de06d9c295ed9039f18af
parent55c4ce6885b577e2b29a4de674d4062a6882afe8 (diff)
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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.
-rw-r--r--ChangeLog13
-rw-r--r--include/atomic.h32
-rw-r--r--malloc/malloc.c3
3 files changed, 35 insertions, 13 deletions
diff --git a/ChangeLog b/ChangeLog
index 48b5d029f3..1e9df428c7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2009-07-13 Jakub Jelinek <jakub@redhat.com>
+
+ * 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 <drepper@redhat.com>
* sysdeps/generic/ldsodefs.h: Add prototype for
diff --git a/include/atomic.h b/include/atomic.h
index 9366f78734..37d0111d5f 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 70e4e58845..0c0182ec0b 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). */