Date: Mon, 16 Jul 2012 16:09:51 -0400 From: Rich Felker <dalias@...ifal.cx> To: musl@...ts.openwall.com Subject: Re: thread local storage On Mon, Jul 16, 2012 at 02:57:22PM -0400, Gregor Richards wrote: > On 07/16/2012 03:02 PM, John Spencer wrote: > >2 out of 14 sabotage followers wanted to use a musl-based system > >as a platform for luajit (and then were never seen again). > >so i looked into adding it... > > > >luajit builds without problems on musl, but then crashes due to a > >lack of TLS. > > > >is it planned to add this feature ? iirc it wasn't mentioned on > >the latest roadmap... > > > > > > > With a quick perusal of the LuaJIT source, this is the only instance > of TLS I see: > > #if LJ_UNWIND_EXT > #if LJ_TARGET_OSX || defined(__OpenBSD__) > /* Sorry, no thread safety for OSX. Complain to Apple, not me. */ > static _Unwind_Exception static_uex; > #else > static __thread _Unwind_Exception static_uex; > #endif > > Convince it to use the same exception as OS X and OpenBSD and you > should be in business. This is broken and non-thread-safe. Not a good idea. Instead try: #define static_uex (*(_Unwind_Exception *)pthread_getspecific(static_uex_key)) where static_uex_key is a pthread_key_t initialized earlier with: pthread_key_create(&static_uex_key, 0); And where the thread-specific value of the key is set in thread startup as: _Unwind_Exception static_uex_local; pthread_setspecific(static_uex_key, &static_uex_local); The simplicity and generality of this solution is why __thread was just a stupid idea to begin with... Rich
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.