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GH-116098: Remove dead frame object creation code (GH-116687)

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Tian Gao 2024-03-12 16:35:28 -07:00 • committed by GitHub
parent 149f7f7ae2
commit a53cc3f494
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2 changed files with 9 additions and 83 deletions
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27
Python/frame.c
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@ -37,24 +37,15 @@ _PyFrame_MakeAndSetFrameObject(_PyInterpreterFrame *frame)
return NULL;
}
PyErr_SetRaisedException(exc);
if (frame->frame_obj) {
// GH-97002: How did we get into this horrible situation? Most likely,
// allocating f triggered a GC collection, which ran some code that
// *also* created the same frame... while we were in the middle of
// creating it! See test_sneaky_frame_object in test_frame.py for a
// concrete example.
//
// Regardless, just throw f away and use that frame instead, since it's
// already been exposed to user code. It's actually a bit tricky to do
// this, since we aren't backed by a real _PyInterpreterFrame anymore.
// Just pretend that we have an owned, cleared frame so frame_dealloc
// doesn't make the situation worse:
f->f_frame = (_PyInterpreterFrame *)f->_f_frame_data;
f->f_frame->owner = FRAME_CLEARED;
f->f_frame->frame_obj = f;
Py_DECREF(f);
return frame->frame_obj;
}
// GH-97002: There was a time when a frame object could be created when we
// are allocating the new frame object f above, so frame->frame_obj would
// be assigned already. That path does not exist anymore. We won't call any
// Python code in this function and garbage collection will not run.
// Notice that _PyFrame_New_NoTrack() can potentially raise a MemoryError,
// but it won't allocate a traceback until the frame unwinds, so we are safe
// here.
assert(frame->frame_obj == NULL);
assert(frame->owner != FRAME_OWNED_BY_FRAME_OBJECT);
assert(frame->owner != FRAME_CLEARED);
f->f_frame = frame;