[3.6] bpo-30604: Move co_extra_freefuncs to interpreter state to avoid crashes in threads (#2015)
* Move co_extra_freefuncs to interpreter state to avoid crashes in
multi-threaded scenarios involving deletion of code objects
* Don't require that extra be zero initialized
* Build test list instead of defining empty test class
* Ensure extra is always assigned on success
* Keep the old fields in the thread state object, just don't use them
Add new linked list of code extra objects on a per-interpreter basis
so that interpreter state size isn't changed
* Rename __PyCodeExtraState_Get and add comment about it going away in 3.7
Fix sort order of import's in test_code.py
* Remove an extraneous space
* Remove docstrings for comments
* Touch up formatting
* Fix casing of coextra local
* Fix casing of another variable
* Prefix PyCodeExtraState with __ to match C API for getting it
* Update NEWS file for bpo-30604
diff --git a/Python/ceval.c b/Python/ceval.c
index eba892c..ea79f5f 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -5453,14 +5453,14 @@
Py_ssize_t
_PyEval_RequestCodeExtraIndex(freefunc free)
{
- PyThreadState *tstate = PyThreadState_Get();
+ __PyCodeExtraState *state = __PyCodeExtraState_Get();
Py_ssize_t new_index;
- if (tstate->co_extra_user_count == MAX_CO_EXTRA_USERS - 1) {
+ if (state->co_extra_user_count == MAX_CO_EXTRA_USERS - 1) {
return -1;
}
- new_index = tstate->co_extra_user_count++;
- tstate->co_extra_freefuncs[new_index] = free;
+ new_index = state->co_extra_user_count++;
+ state->co_extra_freefuncs[new_index] = free;
return new_index;
}
diff --git a/Python/pystate.c b/Python/pystate.c
index ccb0092..92d08c4 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -55,6 +55,7 @@
#endif
static PyInterpreterState *interp_head = NULL;
+static __PyCodeExtraState *coextra_head = NULL;
/* Assuming the current thread holds the GIL, this is the
PyThreadState for the current thread. */
@@ -73,6 +74,12 @@
PyMem_RawMalloc(sizeof(PyInterpreterState));
if (interp != NULL) {
+ __PyCodeExtraState* coextra = PyMem_RawMalloc(sizeof(__PyCodeExtraState));
+ if (coextra == NULL) {
+ PyMem_RawFree(interp);
+ return NULL;
+ }
+
HEAD_INIT();
#ifdef WITH_THREAD
if (head_mutex == NULL)
@@ -92,6 +99,8 @@
interp->importlib = NULL;
interp->import_func = NULL;
interp->eval_frame = _PyEval_EvalFrameDefault;
+ coextra->co_extra_user_count = 0;
+ coextra->interp = interp;
#ifdef HAVE_DLOPEN
#if HAVE_DECL_RTLD_NOW
interp->dlopenflags = RTLD_NOW;
@@ -103,6 +112,8 @@
HEAD_LOCK();
interp->next = interp_head;
interp_head = interp;
+ coextra->next = coextra_head;
+ coextra_head = coextra;
HEAD_UNLOCK();
}
@@ -147,9 +158,10 @@
PyInterpreterState_Delete(PyInterpreterState *interp)
{
PyInterpreterState **p;
+ __PyCodeExtraState **pextra;
zapthreads(interp);
HEAD_LOCK();
- for (p = &interp_head; ; p = &(*p)->next) {
+ for (p = &interp_head; /* N/A */; p = &(*p)->next) {
if (*p == NULL)
Py_FatalError(
"PyInterpreterState_Delete: invalid interp");
@@ -159,6 +171,18 @@
if (interp->tstate_head != NULL)
Py_FatalError("PyInterpreterState_Delete: remaining threads");
*p = interp->next;
+
+ for (pextra = &coextra_head; ; pextra = &(*pextra)->next) {
+ if (*pextra == NULL)
+ Py_FatalError(
+ "PyInterpreterState_Delete: invalid extra");
+ __PyCodeExtraState* extra = *pextra;
+ if (extra->interp == interp) {
+ *pextra = extra->next;
+ PyMem_RawFree(extra);
+ break;
+ }
+ }
HEAD_UNLOCK();
PyMem_RawFree(interp);
#ifdef WITH_THREAD
@@ -224,7 +248,6 @@
tstate->coroutine_wrapper = NULL;
tstate->in_coroutine_wrapper = 0;
- tstate->co_extra_user_count = 0;
tstate->async_gen_firstiter = NULL;
tstate->async_gen_finalizer = NULL;
@@ -548,6 +571,23 @@
return oldts;
}
+__PyCodeExtraState*
+__PyCodeExtraState_Get() {
+ PyInterpreterState* interp = PyThreadState_Get()->interp;
+
+ HEAD_LOCK();
+ for (__PyCodeExtraState* cur = coextra_head; cur != NULL; cur = cur->next) {
+ if (cur->interp == interp) {
+ HEAD_UNLOCK();
+ return cur;
+ }
+ }
+ HEAD_UNLOCK();
+
+ Py_FatalError("__PyCodeExtraState_Get: no code state for interpreter");
+ return NULL;
+}
+
/* An extension mechanism to store arbitrary additional per-thread state.
PyThreadState_GetDict() returns a dictionary that can be used to hold such
state; the caller should pick a unique key and store its state there. If