Backport r60148 and r65481: sanity checks to avoid infinite loops.
diff --git a/Python/thread.c b/Python/thread.c
index 3a2c7af..be4d092 100644
--- a/Python/thread.c
+++ b/Python/thread.c
@@ -264,15 +264,25 @@
static struct key *
find_key(int key, void *value)
{
- struct key *p;
+ struct key *p, *prev_p;
long id = PyThread_get_thread_ident();
if (!keymutex)
return NULL;
PyThread_acquire_lock(keymutex, 1);
+ prev_p = NULL;
for (p = keyhead; p != NULL; p = p->next) {
if (p->id == id && p->key == key)
goto Done;
+ /* Sanity check. These states should never happen but if
+ * they do we must abort. Otherwise we'll end up spinning in
+ * in a tight loop with the lock held. A similar check is done
+ * in pystate.c tstate_delete_common(). */
+ if (p == prev_p)
+ Py_FatalError("tls find_key: small circular list(!)");
+ prev_p = p;
+ if (p->next == keyhead)
+ Py_FatalError("tls find_key: circular list(!)");
}
if (value == NULL) {
assert(p == NULL);