From f69319d5a7d3a3ccb46b28ee2b0fd9053c6415ac Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Timo=20Ter=C3=A4s?= Date: Thu, 24 Mar 2011 13:27:36 +0200 Subject: libdl: rudimentary locking for dlopen/dlsym/dlclose MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This implements big-dlfcn lock to allow multithreaded usage of dlopen/dlsym/dlclose. We should really clean up the dl code so we can use more fine grained locking or even RCU where appropriate. But at least we won't crash now. Signed-off-by: Timo Teräs Signed-off-by: Bernhard Reutner-Fischer --- ldso/libdl/libdl.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 49 insertions(+), 5 deletions(-) (limited to 'ldso/libdl') diff --git a/ldso/libdl/libdl.c b/ldso/libdl/libdl.c index eb879d299..bc3ef8aa1 100644 --- a/ldso/libdl/libdl.c +++ b/ldso/libdl/libdl.c @@ -34,6 +34,7 @@ #include #include /* Needed for 'strstr' prototype' */ #include +#include #ifdef __UCLIBC_HAS_TLS__ #include @@ -44,6 +45,10 @@ extern void _dl_add_to_slotinfo(struct link_map *l); #endif +/* TODO: get rid of global lock and use more finegrained locking, or + * perhaps RCU for the global structures */ +__UCLIBC_MUTEX_STATIC(_dl_mutex, PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP); + #ifdef SHARED # if defined(USE_TLS) && USE_TLS # include @@ -291,7 +296,7 @@ static ptrdiff_t _dl_build_local_scope (struct elf_resolve **list, return p - list; } -void *dlopen(const char *libname, int flag) +static void *do_dlopen(const char *libname, int flag) { struct elf_resolve *tpnt, *tfrom; struct dyn_elf *dyn_chain, *rpnt = NULL, *dyn_ptr, *relro_ptr, *handle; @@ -650,7 +655,18 @@ oops: return NULL; } -void *dlsym(void *vhandle, const char *name) +void *dlopen(const char *libname, int flag) +{ + void *ret; + + __UCLIBC_MUTEX_CONDITIONAL_LOCK(_dl_mutex, 1); + ret = do_dlopen(libname, flag); + __UCLIBC_MUTEX_CONDITIONAL_UNLOCK(_dl_mutex, 1); + + return ret; +} + +static void *do_dlsym(void *vhandle, const char *name, void *caller_address) { struct elf_resolve *tpnt, *tfrom; struct dyn_elf *handle; @@ -698,7 +714,7 @@ void *dlsym(void *vhandle, const char *name) * dynamic loader itself, as it doesn't know * how to properly treat it. */ - from = (ElfW(Addr)) __builtin_return_address(0); + from = (ElfW(Addr)) caller_address; tfrom = NULL; for (rpnt = _dl_symbol_tables; rpnt; rpnt = rpnt->next) { @@ -735,6 +751,17 @@ out: return ret; } +void *dlsym(void *vhandle, const char *name) +{ + void *ret; + + __UCLIBC_MUTEX_CONDITIONAL_LOCK(_dl_mutex, 1); + ret = do_dlsym(vhandle, name, __builtin_return_address(0)); + __UCLIBC_MUTEX_CONDITIONAL_UNLOCK(_dl_mutex, 1); + + return ret; +} + #if 0 void *dlvsym(void *vhandle, const char *name, const char *version) { @@ -1018,7 +1045,13 @@ static int do_dlclose(void *vhandle, int need_fini) int dlclose(void *vhandle) { - return do_dlclose(vhandle, 1); + int ret; + + __UCLIBC_MUTEX_CONDITIONAL_LOCK(_dl_mutex, 1); + ret = do_dlclose(vhandle, 1); + __UCLIBC_MUTEX_CONDITIONAL_UNLOCK(_dl_mutex, 1); + + return ret; } char *dlerror(void) @@ -1065,7 +1098,7 @@ int dlinfo(void) return 0; } -int dladdr(const void *__address, Dl_info * __info) +static int do_dladdr(const void *__address, Dl_info * __info) { struct elf_resolve *pelf; struct elf_resolve *rpnt; @@ -1177,3 +1210,14 @@ int dladdr(const void *__address, Dl_info * __info) } } #endif + +int dladdr(const void *__address, Dl_info * __info) +{ + int ret; + + __UCLIBC_MUTEX_CONDITIONAL_LOCK(_dl_mutex, 1); + ret = do_dladdr(__address, __info); + __UCLIBC_MUTEX_CONDITIONAL_UNLOCK(_dl_mutex, 1); + + return ret; +} -- cgit v1.2.3