From 7df7136e20933fd3a498bd58bff7975a24790516 Mon Sep 17 00:00:00 2001
From: Copilot <198982749+Copilot@users.noreply.github.com>
Date: Wed, 3 Jun 2026 16:22:40 +0900
Subject: [PATCH] Guard `Packer` buffer protocol hooks with Cython critical
 sections (#686)

---
 msgpack/_packer.pyx | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/msgpack/_packer.pyx b/msgpack/_packer.pyx
index 2d92e8a..277239d 100644
--- a/msgpack/_packer.pyx
+++ b/msgpack/_packer.pyx
@@ -360,9 +360,11 @@ cdef class Packer:
         """
         return memoryview(self)
 
+    @cython.critical_section
     def __getbuffer__(self, Py_buffer *buffer, int flags):
         PyBuffer_FillInfo(buffer, self, self.pk.buf, self.pk.length, 1, flags)
         self.exports += 1
 
+    @cython.critical_section
     def __releasebuffer__(self, Py_buffer *buffer):
         self.exports -= 1