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authorLeonid Lisovskiy <lly.dev@gmail.com>2016-06-20 17:29:45 (GMT)
committerWaldemar Brodkorb <wbx@uclibc-ng.org>2016-06-22 06:02:51 (GMT)
commitbc5949fd4f8cddf4eee74492c86a8a72f4dee0e7 (patch)
tree68cf04f3eade770ecd41bfb782bc5e9f51acbe94
parent0bc1394750885d4e4b2064aff6c48dd542c6f4b8 (diff)
ldso: fix dlsym hang when reloading DSOs
It can happen under certain cases that the DSO had refcount 0, but was already loaded. (NODELETE flag is set, or it is pulled in via both NEEDED dependency and explicit dlopen()). Add extra reference count for NODELETE objects, this will ensure that the reference count never drops below one. It is improved version of http://lists.busybox.net/pipermail/uclibc/2013-June/047826.html Signed-off-by: Leonid Lisovskiy <lly.dev@gmail.com>
-rw-r--r--ldso/ldso/dl-elf.c2
-rw-r--r--ldso/libdl/libdl.c4
-rw-r--r--test/dlopen/Makefile.in4
-rw-r--r--test/dlopen/nodelete1.c59
4 files changed, 66 insertions, 3 deletions
diff --git a/ldso/ldso/dl-elf.c b/ldso/ldso/dl-elf.c
index 8f71aeb..a046aeb 100644
--- a/ldso/ldso/dl-elf.c
+++ b/ldso/ldso/dl-elf.c
@@ -884,6 +884,8 @@ struct elf_resolve *_dl_load_elf_shared_library(unsigned int rflags,
#endif
(*rpnt)->dyn = tpnt;
tpnt->usage_count++;
+ if (tpnt->rtld_flags & RTLD_NODELETE)
+ tpnt->usage_count++;
#ifdef __LDSO_STANDALONE_SUPPORT__
tpnt->libtype = (epnt->e_type == ET_DYN) ? elf_lib : elf_executable;
#else
diff --git a/ldso/libdl/libdl.c b/ldso/libdl/libdl.c
index 489c787..0cf3b70 100644
--- a/ldso/libdl/libdl.c
+++ b/ldso/libdl/libdl.c
@@ -818,7 +818,7 @@ static int do_dlclose(void *vhandle, int need_fini)
_dl_handles = rpnt->next_handle;
_dl_if_debug_print("%s: usage count: %d\n",
handle->dyn->libname, handle->dyn->usage_count);
- if (handle->dyn->usage_count != 1 || (handle->dyn->rtld_flags & RTLD_NODELETE)) {
+ if (handle->dyn->usage_count != 1) {
handle->dyn->usage_count--;
free(handle);
return 0;
@@ -840,7 +840,7 @@ static int do_dlclose(void *vhandle, int need_fini)
for (j = 0; j < handle->init_fini.nlist; ++j) {
tpnt = handle->init_fini.init_fini[j];
tpnt->usage_count--;
- if (tpnt->usage_count == 0 && !(tpnt->rtld_flags & RTLD_NODELETE)) {
+ if (tpnt->usage_count == 0) {
if ((tpnt->dynamic_info[DT_FINI]
|| tpnt->dynamic_info[DT_FINI_ARRAY])
&& need_fini
diff --git a/test/dlopen/Makefile.in b/test/dlopen/Makefile.in
index 0bed0f7..740453a 100644
--- a/test/dlopen/Makefile.in
+++ b/test/dlopen/Makefile.in
@@ -5,7 +5,7 @@
export UCLIBC_ONLY := 1
TESTS := dltest dltest2 dlstatic test1 test2 test3 dlundef dlafk dladdr \
- testscope nodelete tst-origin
+ testscope nodelete nodelete1 tst-origin
ifneq ($(HAVE_SHARED),y)
TESTS_DISABLED := test3
@@ -80,3 +80,5 @@ LDFLAGS_nodelete := -rdynamic -ldl
LDFLAGS_nodelmod1.so := -Wl,-z,nodelete
LDFLAGS_nodelmod3.so := ./nodelmod4.so
LDFLAGS_nodelmod4.so := -Wl,-z,nodelete
+nodelete1: nodelmod1.so nodelmod2.so
+LDFLAGS_nodelete1 := -rdynamic -ldl
diff --git a/test/dlopen/nodelete1.c b/test/dlopen/nodelete1.c
new file mode 100644
index 0000000..720e37f
--- /dev/null
+++ b/test/dlopen/nodelete1.c
@@ -0,0 +1,59 @@
+#include <dlfcn.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+
+int fini_ran;
+
+#define LIBNAME1 "nodelmod1.so"
+
+static int
+do_test (void)
+{
+ /* Verify ability to reload RTLD_NODELETE libraries.
+ */
+ void *p;
+
+ p = dlopen (LIBNAME1, RTLD_NOW);
+ if (p == NULL)
+ {
+ printf ("failed to load "LIBNAME1": %s\n", dlerror ());
+ exit (1);
+ }
+
+ if (dlclose (p) != 0)
+ {
+ puts ("failed to close "LIBNAME1"");
+ exit (1);
+ }
+
+ p = dlopen (LIBNAME1, RTLD_LAZY);
+ if (p == NULL)
+ {
+ printf ("failed to load "LIBNAME1": %s\n", dlerror ());
+ exit (1);
+ }
+
+ if (dlclose (p) != 0)
+ {
+ puts ("failed to close "LIBNAME1"");
+ exit (1);
+ }
+
+ p = dlopen ("nodelmod2.so", RTLD_LAZY);
+ if (p == NULL)
+ {
+ printf ("failed to load \"nodelmod2.so\": %s\n", dlerror ());
+ exit (1);
+ }
+ if (dlclose (p) != 0)
+ {
+ puts ("failed to close \"nodelmod2.so\"");
+ exit (1);
+ }
+
+ return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"