As explained by Alexander Monakov, dlsym() is defined to be pure, thus the compiler is allowed to assume that there is no need to write the changes performed by setup_static_allocator() into memory prior to calling dlsym(). The added cmm_barrier() forces the compiler to write the changes into memory.
For more details refer to: http://lists.lttng.org/pipermail/lttng-dev/2014-February/022389.html Signed-off-by: Paul Woegerer <[email protected]> --- liblttng-ust-libc-wrapper/lttng-ust-malloc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/liblttng-ust-libc-wrapper/lttng-ust-malloc.c b/liblttng-ust-libc-wrapper/lttng-ust-malloc.c index 8296ae2..7dd647f 100644 --- a/liblttng-ust-libc-wrapper/lttng-ust-malloc.c +++ b/liblttng-ust-libc-wrapper/lttng-ust-malloc.c @@ -198,6 +198,9 @@ void lookup_all_symbols(void) */ setup_static_allocator(); + /* Dlsym is defined pure -> force static alloc into memory */ + cmm_barrier(); + /* Perform the actual lookups */ af.calloc = dlsym(RTLD_NEXT, "calloc"); af.malloc = dlsym(RTLD_NEXT, "malloc"); @@ -207,7 +210,7 @@ void lookup_all_symbols(void) af.posix_memalign = dlsym(RTLD_NEXT, "posix_memalign"); /* Populate the new allocator functions */ - memcpy(&cur_alloc, &af, sizeof(cur_alloc)); + cur_alloc = af; } void *malloc(size_t size) -- 1.8.5.2 _______________________________________________ lttng-dev mailing list [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
