aboutsummaryrefslogtreecommitdiff
path: root/malloc
diff options
context:
space:
mode:
authorAndreas Jaeger <aj@suse.de>2012-05-03 22:12:59 +0200
committerAndreas Jaeger <aj@suse.de>2012-05-03 22:12:59 +0200
commitf0c1dedf0df71b4029d9b0ce8ba19d8af2a60af5 (patch)
tree059f1ba1edcd7ed788946cb33790a17e6c751f0a /malloc
parenta65ef2aefa3167e531d1df0047df804069a8c36f (diff)
downloadglibc-f0c1dedf0df71b4029d9b0ce8ba19d8af2a60af5.zip
glibc-f0c1dedf0df71b4029d9b0ce8ba19d8af2a60af5.tar.gz
glibc-f0c1dedf0df71b4029d9b0ce8ba19d8af2a60af5.tar.bz2
Fix tst-obprintf - and mcheck in general
tst-obprintf failed with GCC 4.7. It turned out that this is the fault of GCC optimizing away the following from malloc/mcheck.c: /* We call malloc() once here to ensure it is initialized. */ void *p = malloc (0); free (p); gcc sees the malloc(0);free pair and removes it completely. And now malloc is not properly initialized and we screw up if both mcheck is used (via tst-obprintf) and MALLOC_CHECK_ is set (as it is in my environment).
Diffstat (limited to 'malloc')
-rw-r--r--malloc/mcheck.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/malloc/mcheck.c b/malloc/mcheck.c
index 9213740..9d8a414 100644
--- a/malloc/mcheck.c
+++ b/malloc/mcheck.c
@@ -370,6 +370,10 @@ mabort (enum mcheck_status status)
#endif
}
+/* Memory barrier so that GCC does not optimize out the argument. */
+#define malloc_opt_barrier(x) \
+({ __typeof (x) __x = x; __asm ("" : "+m" (__x)); __x; })
+
int
mcheck (func)
void (*func) (enum mcheck_status);
@@ -381,6 +385,8 @@ mcheck (func)
{
/* We call malloc() once here to ensure it is initialized. */
void *p = malloc (0);
+ /* GCC might optimize out the malloc/free pair without a barrier. */
+ p = malloc_opt_barrier (p);
free (p);
old_free_hook = __free_hook;