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bpo-39877: Fix PyEval_RestoreThread() for daemon threads (GH-18811)

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* exit_thread_if_finalizing() does now access directly _PyRuntime
  variable, rather than using tstate->interp->runtime since tstate
  can be a dangling pointer after Py_Finalize() has been called.
* exit_thread_if_finalizing() is now called *before* calling
  take_gil(). _PyRuntime.finalizing is an atomic variable,
  we don't need to hold the GIL to access it.
* Add ensure_tstate_not_null() function to check that tstate is not
  NULL at runtime. Check tstate earlier. take_gil() does not longer
  check if tstate is NULL.

Cleanup:

* PyEval_RestoreThread() no longer saves/restores errno: it's already
  done inside take_gil().
* PyEval_AcquireLock(), PyEval_AcquireThread(),
  PyEval_RestoreThread() and _PyEval_EvalFrameDefault() now check if
  tstate is valid with the new is_tstate_valid() function which uses
  _PyMem_IsPtrFreed().
This commit is contained in:
Victor Stinner 2020-03-08 11:57:45 +01:00 • committed by GitHub
parent d5aa2e941c
commit eb4e2ae2b8
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4 changed files with 74 additions and 26 deletions
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11
Python/ceval_gil.h
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@ -180,15 +180,17 @@ drop_gil(struct _ceval_runtime_state *ceval, PyThreadState *tstate)
#endif
}
/* Take the GIL.
The function saves errno at entry and restores its value at exit.
tstate must be non-NULL. */
static void
take_gil(struct _ceval_runtime_state *ceval, PyThreadState *tstate)
{
if (tstate == NULL) {
Py_FatalError("take_gil: NULL tstate");
}
int err = errno;
struct _gil_runtime_state *gil = &ceval->gil;
int err = errno;
MUTEX_LOCK(gil->mutex);
if (!_Py_atomic_load_relaxed(&gil->locked)) {
@ -240,6 +242,7 @@ take_gil(struct _ceval_runtime_state *ceval, PyThreadState *tstate)
}
MUTEX_UNLOCK(gil->mutex);
errno = err;
}