Make _PyWeakref_GetWeakrefCount thread-safe

mpage · mpage · commit c9b3bf97c016 · 2024-03-22T14:16:04.000-07:00
diff --git a/Include/internal/pycore_weakref.h b/Include/internal/pycore_weakref.h
@@ -71,6 +71,8 @@ static inline int _PyWeakref_IS_DEAD(PyObject *ref_obj)
     return ret;
 }
 
+// NB: In free-threaded builds the referenced object must be live for the
+// duration of the call.
 extern Py_ssize_t _PyWeakref_GetWeakrefCount(PyWeakReference *head);
 
 extern void _PyWeakref_ClearRef(PyWeakReference *self);
@@ -79,4 +81,3 @@ extern void _PyWeakref_ClearRef(PyWeakReference *self);
 }
 #endif
 #endif /* !Py_INTERNAL_WEAKREF_H */
-
diff --git a/Objects/weakrefobject.c b/Objects/weakrefobject.c
@@ -108,11 +108,15 @@ Py_ssize_t
 _PyWeakref_GetWeakrefCount(PyWeakReference *head)
 {
     Py_ssize_t count = 0;
-
+    if (head == NULL) {
+        return 0;
+    }
+    Py_BEGIN_CRITICAL_SECTION(head->wr_object);
     while (head != NULL) {
         ++count;
         head = head->wr_next;
     }
+    Py_END_CRITICAL_SECTION();
     return count;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -71,6 +71,8 @@ static inline int _PyWeakref_IS_DEAD(PyObject *ref_obj)`
`71`	`71`	`return ret;`
`72`	`72`	`}`
`73`	`73`
	`74`	`+// NB: In free-threaded builds the referenced object must be live for the`
	`75`	`+// duration of the call.`
`74`	`76`	`extern Py_ssize_t _PyWeakref_GetWeakrefCount(PyWeakReference *head);`
`75`	`77`
`76`	`78`	`extern void _PyWeakref_ClearRef(PyWeakReference *self);`
`@@ -79,4 +81,3 @@ extern void _PyWeakref_ClearRef(PyWeakReference *self);`
`79`	`81`	`}`
`80`	`82`	`#endif`
`81`	`83`	`#endif /* !Py_INTERNAL_WEAKREF_H */`
`82`		`-`
Original file line number	Diff line number	Diff line change
`@@ -108,11 +108,15 @@ Py_ssize_t`
`108`	`108`	`_PyWeakref_GetWeakrefCount(PyWeakReference *head)`
`109`	`109`	`{`
`110`	`110`	`Py_ssize_t count = 0;`
`111`		`-`
	`111`	`+ if (head == NULL) {`
	`112`	`+ return 0;`
	`113`	`+ }`
	`114`	`+ Py_BEGIN_CRITICAL_SECTION(head->wr_object);`
`112`	`115`	`while (head != NULL) {`
`113`	`116`	`++count;`
`114`	`117`	`head = head->wr_next;`
`115`	`118`	`}`
	`119`	`+ Py_END_CRITICAL_SECTION();`
`116`	`120`	`return count;`
`117`	`121`	`}`
`118`	`122`