diff options
Diffstat (limited to 'src/runtime/cgo/gcc_libinit.c')
| -rw-r--r-- | src/runtime/cgo/gcc_libinit.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/src/runtime/cgo/gcc_libinit.c b/src/runtime/cgo/gcc_libinit.c index 57620fe4de..9676593211 100644 --- a/src/runtime/cgo/gcc_libinit.c +++ b/src/runtime/cgo/gcc_libinit.c @@ -17,6 +17,14 @@ static pthread_cond_t runtime_init_cond = PTHREAD_COND_INITIALIZER; static pthread_mutex_t runtime_init_mu = PTHREAD_MUTEX_INITIALIZER; static int runtime_init_done; +// pthread_g is a pthread specific key, for storing the g that binded to the C thread. +// The registered pthread_key_destructor will dropm, when the pthread-specified value g is not NULL, +// while a C thread is exiting. +static pthread_key_t pthread_g; +static void pthread_key_destructor(void* g); +uintptr_t x_cgo_pthread_key_created; +void (*x_crosscall2_ptr)(void (*fn)(void *), void *, int, size_t); + // The context function, used when tracing back C calls into Go. static void (*cgo_context_function)(struct context_arg*); @@ -39,6 +47,12 @@ _cgo_wait_runtime_init_done(void) { pthread_cond_wait(&runtime_init_cond, &runtime_init_mu); } + // The key and x_cgo_pthread_key_created are for the whole program, + // whereas the specific and destructor is per thread. + if (x_cgo_pthread_key_created == 0 && pthread_key_create(&pthread_g, pthread_key_destructor) == 0) { + x_cgo_pthread_key_created = 1; + } + // TODO(iant): For the case of a new C thread calling into Go, such // as when using -buildmode=c-archive, we know that Go runtime // initialization is complete but we do not know that all Go init @@ -61,6 +75,16 @@ _cgo_wait_runtime_init_done(void) { return 0; } +// Store the g into a thread-specific value associated with the pthread key pthread_g. +// And pthread_key_destructor will dropm when the thread is exiting. +void x_cgo_bindm(void* g) { + // We assume this will always succeed, otherwise, there might be extra M leaking, + // when a C thread exits after a cgo call. + // We only invoke this function once per thread in runtime.needAndBindM, + // and the next calls just reuse the bound m. + pthread_setspecific(pthread_g, g); +} + void x_cgo_notify_runtime_init_done(void* dummy __attribute__ ((unused))) { pthread_mutex_lock(&runtime_init_mu); @@ -110,3 +134,14 @@ _cgo_try_pthread_create(pthread_t* thread, const pthread_attr_t* attr, void* (*p } return EAGAIN; } + +static void +pthread_key_destructor(void* g) { + if (x_crosscall2_ptr != NULL) { + // fn == NULL means dropm. + // We restore g by using the stored g, before dropm in runtime.cgocallback, + // since the g stored in the TLS by Go might be cleared in some platforms, + // before this destructor invoked. + x_crosscall2_ptr(NULL, g, 0, 0); + } +} |