From: Maria Matejka <mq@ucw.cz>
Date: Tue, 4 Mar 2025 12:02:01 +0000 (+0100)
Subject: RCU Unwinder stores where it came from last time
X-Git-Tag: v3.0.2~12
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b5d46eb68b2861d1243528d5acc671db1459165a;p=thirdparty%2Fbird.git

RCU Unwinder stores where it came from last time

This information is vital for stuck situations where the
RCU Unwinder keeps longjumping away.
---

diff --git a/lib/locking.h b/lib/locking.h
index 60928ecc0..8f30e67da 100644
--- a/lib/locking.h
+++ b/lib/locking.h
@@ -493,6 +493,8 @@ static inline void locking_unwind(struct lock_order *desired)
 
 struct rcu_unwinder {
   struct lock_order locking_stack;
+  const char *file;
+  u32 line;
   u32 retry;
   u8 fast;
   jmp_buf buf;
@@ -522,7 +524,7 @@ static inline void _rcu_unwinder_unlock_(struct rcu_unwinder *o UNUSED)
   _i->locking_stack = locking_stack;					\
   rcu_read_lock();							\
 
-#define RCU_RETRY(_i) do { if (_i) longjmp(_i->buf, 1); else bug("No rcu retry allowed here"); } while (0)
+#define RCU_RETRY(_i) do { if (_i) { _i->file = __FILE__; _i->line = __LINE__; longjmp(_i->buf, 1); } else bug("No rcu retry allowed here"); } while (0)
 
 #define RCU_RETRY_FAST(_i) do { (_i)->fast++; RCU_RETRY(_i); } while (0)