https://github.com/python/cpython/commit/96ef4c511f3ec763dbb06a1f3c23c658a09403a1
commit: 96ef4c511f3ec763dbb06a1f3c23c658a09403a1
branch: main
author: Kumar Aditya <[email protected]>
committer: kumaraditya303 <[email protected]>
date: 2025-03-25T16:48:46+05:30
summary:
gh-127945: add locking to malloc closure in free-threading (#131662)
The freelist is not thread safe in free-threading so this adds lock around it
make it thread safe in free-threading.
files:
M Modules/_ctypes/malloc_closure.c
diff --git a/Modules/_ctypes/malloc_closure.c b/Modules/_ctypes/malloc_closure.c
index bb4f8f21bd3f77..80ba96614bff79 100644
--- a/Modules/_ctypes/malloc_closure.c
+++ b/Modules/_ctypes/malloc_closure.c
@@ -27,6 +27,16 @@
/******************************************************************/
+
+#ifdef Py_GIL_DISABLED
+static PyMutex malloc_closure_lock;
+# define MALLOC_CLOSURE_LOCK() PyMutex_Lock(&malloc_closure_lock)
+# define MALLOC_CLOSURE_UNLOCK() PyMutex_Unlock(&malloc_closure_lock)
+#else
+# define MALLOC_CLOSURE_LOCK() ((void)0)
+# define MALLOC_CLOSURE_UNLOCK() ((void)0)
+#endif
+
typedef union _tagITEM {
ffi_closure closure;
union _tagITEM *next;
@@ -110,9 +120,11 @@ void Py_ffi_closure_free(void *p)
}
#endif
#endif
+ MALLOC_CLOSURE_LOCK();
ITEM *item = (ITEM *)p;
item->next = free_list;
free_list = item;
+ MALLOC_CLOSURE_UNLOCK();
}
/* return one item from the free list, allocating more if needed */
@@ -131,11 +143,15 @@ void *Py_ffi_closure_alloc(size_t size, void** codeloc)
}
#endif
#endif
+ MALLOC_CLOSURE_LOCK();
ITEM *item;
- if (!free_list)
+ if (!free_list) {
more_core();
- if (!free_list)
+ }
+ if (!free_list) {
+ MALLOC_CLOSURE_UNLOCK();
return NULL;
+ }
item = free_list;
free_list = item->next;
#ifdef _M_ARM
@@ -144,5 +160,6 @@ void *Py_ffi_closure_alloc(size_t size, void** codeloc)
#else
*codeloc = (void *)item;
#endif
+ MALLOC_CLOSURE_UNLOCK();
return (void *)item;
}
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