Repository navigation
Conversation
Py_CLEAR writes NULL non-atomically, racing with the acquire load in _PyObject_TryGetInstanceAttribute. Invalidating the inline values does not exclude lookups already in flight. Use a release store before decref, preserving the clear-before-decref ordering.
msullivan
reviewed
Oct 23, 2026
| for (Py_ssize_t i = 0; i < values->capacity; i++) { | ||
| Py_CLEAR(values->values[i]); | ||
| PyObject *value = values->values[i]; | ||
| FT_ATOMIC_STORE_PTR_RELEASE(values->values[i], NULL); |
Contributor
There was a problem hiding this comment.
Is it worth a comment about what the conflicting reads are?
Member
|
Maybe more explicit about where the load is, e.g. // Pair with the acquire load in _PyObject_TryGetInstanceAttribute(),
// which may read this slot after passing the initial validity check.
FT_ATOMIC_STORE_PTR_RELEASE(values->values[i], NULL);Or, do you not want to explicitly name the function? |
nascheme
approved these changes
Oct 23, 2026
Contributor
Author
I was explicitly not naming the function to avoid the situation where the comment gets out of date due to refactoring. |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Py_CLEAR writes NULL non-atomically, racing with the acquire load in _PyObject_TryGetInstanceAttribute. Invalidating the inline values does not exclude lookups already in flight.
Authored with AI.
_PyObject_TryGetInstanceAttributeandclear_inline_values#160496