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 <[email protected]> --- TODO | 1 + ldso/libdl/libdl.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++---- 2 files changed, 50 insertions(+), 5 deletions(-) diff --git a/TODO b/TODO index ae305a5..95cabd5 100644 --- a/TODO +++ b/TODO @@ -101,6 +101,7 @@ TODO list for AFTER the uClibc 1.0.0 release: *) run 'nm -D --size-sort -t d libuClibc-0.9.26.so' and work on the biggest things (i.e. stuff at the end of the list) to make them smaller. + *) Fix dlopen/dlsym/dlclose locking to more fine grained or use RCU <more wishlist items here> diff --git a/ldso/libdl/libdl.c b/ldso/libdl/libdl.c index 68cd579..e007f54 100644 --- a/ldso/libdl/libdl.c +++ b/ldso/libdl/libdl.c @@ -34,6 +34,7 @@ #include <stdio.h> #include <string.h> /* Needed for 'strstr' prototype' */ #include <stdbool.h> +#include <bits/uClibc_mutex.h> #ifdef __UCLIBC_HAS_TLS__ #include <tls.h> @@ -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 <dl-tls.h> @@ -271,7 +276,7 @@ void dl_cleanup(void) } } -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; @@ -605,7 +610,18 @@ 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; @@ -653,7 +669,7 @@ 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) { @@ -690,6 +706,17 @@ 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) { @@ -957,7 +984,13 @@ 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) @@ -1004,7 +1037,7 @@ 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; @@ -1108,3 +1141,14 @@ 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; +} -- 1.7.1 _______________________________________________ uClibc mailing list [email protected] http://lists.busybox.net/mailman/listinfo/uclibc
