From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 13 Nov 2014 20:46:04 +0000 (-0500)
Subject: Detect unbalanced lock/unlock
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=2bae154a80e64dbfc4c7701049f223d869cab695;p=userspace-rcu.git

Detect unbalanced lock/unlock

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/urcu-checker.c b/urcu-checker.c
index cd4721d..97220ab 100644
--- a/urcu-checker.c
+++ b/urcu-checker.c
@@ -67,7 +67,7 @@ static inline pid_t gettid(void)
 		(long) getpid(), (long) gettid(), ## args)
 
 struct urcu_debug_entry {
-	void *ip;
+	char *func;
 	int depth;
 };
 
@@ -145,16 +145,32 @@ void print_bt(struct backtrace *bt)
 void rcu_read_lock_debug(void)
 {
 	struct urcu_debug_stack *r = &URCU_TLS(rcu_debug_stack);
+	char *func = get_symbol(__builtin_return_address(0));
 
-	r->stack[r->stackend++].ip = __builtin_return_address(0);
+	r->stack[r->stackend++].func = func;
 }
 
 void rcu_read_unlock_debug(void)
 {
 	struct urcu_debug_stack *r = &URCU_TLS(rcu_debug_stack);
+	char *func = get_symbol(__builtin_return_address(0));
 
 	assert(r->stackend != 0);
-	r->stack[--r->stackend].ip = NULL;
+	if (r->stack[r->stackend - 1].func && func &&
+			strcmp(r->stack[r->stackend - 1].func,
+				func) != 0) {
+		struct backtrace bt;
+
+		err_printf("URCU lock/unlock caller mismatch: lock by <%s> unlock by <%s>\n",
+			r->stack[r->stackend - 1].func, func);
+		save_backtrace(&bt);
+		print_bt(&bt);
+		free_backtrace(&bt);
+	}
+	r->stackend--;
+	free(r->stack[r->stackend].func);
+	r->stack[r->stackend].func = NULL;
+	free(func);
 }
 
 void rcu_read_ongoing_check_debug(const char *func)
@@ -163,12 +179,13 @@ void rcu_read_ongoing_check_debug(const char *func)
 
 	if (r->stackend == 0) {
 		struct backtrace bt;
+		char *func = get_symbol(__builtin_return_address(0));
 
 		err_printf("rcu_dereference() used outside of critical section at %p <%s>\n",
-			__builtin_return_address(0),
-			get_symbol(__builtin_return_address(0)));
+			__builtin_return_address(0), func);
 		save_backtrace(&bt);
 		print_bt(&bt);
 		free_backtrace(&bt);
+		free(func);
 	}
 }
diff --git a/urcu/static/urcu-bp.h b/urcu/static/urcu-bp.h
index 0bdefff..0ae18d6 100644
--- a/urcu/static/urcu-bp.h
+++ b/urcu/static/urcu-bp.h
@@ -152,7 +152,8 @@ static inline void _rcu_read_lock_update(unsigned long tmp)
  * intent is that this function meets the 10-line criterion in LGPL,
  * allowing this function to be invoked directly from non-LGPL code.
  */
-static inline void _rcu_read_lock(void)
+static inline __attribute__((always_inline))
+void _rcu_read_lock(void)
 {
 	unsigned long tmp;
 
@@ -169,7 +170,8 @@ static inline void _rcu_read_lock(void)
  * 10 lines of code, and is intended to be usable by non-LGPL code, as
  * called out in LGPL.
  */
-static inline void _rcu_read_unlock(void)
+static inline __attribute__((always_inline))
+void _rcu_read_unlock(void)
 {
 	/*
 	 * Finish using rcu before decrementing the pointer.
diff --git a/urcu/static/urcu-qsbr.h b/urcu/static/urcu-qsbr.h
index 1ef830a..4092d6b 100644
--- a/urcu/static/urcu-qsbr.h
+++ b/urcu/static/urcu-qsbr.h
@@ -131,7 +131,8 @@ static inline enum rcu_state rcu_reader_state(unsigned long *ctr)
  * function meets the 10-line criterion for LGPL, allowing this function
  * to be invoked directly from non-LGPL code.
  */
-static inline void _rcu_read_lock(void)
+static inline __attribute__((always_inline))
+void _rcu_read_lock(void)
 {
 	rcu_read_lock_debug();
 	rcu_assert(URCU_TLS(rcu_reader).ctr);
@@ -144,7 +145,8 @@ static inline void _rcu_read_lock(void)
  * function meets the 10-line criterion for LGPL, allowing this function
  * to be invoked directly from non-LGPL code.
  */
-static inline void _rcu_read_unlock(void)
+static inline __attribute__((always_inline))
+void _rcu_read_unlock(void)
 {
 	rcu_read_unlock_debug();
 }
diff --git a/urcu/static/urcu.h b/urcu/static/urcu.h
index 0fe32e8..9659a2f 100644
--- a/urcu/static/urcu.h
+++ b/urcu/static/urcu.h
@@ -216,7 +216,8 @@ static inline void _rcu_read_lock_update(unsigned long tmp)
  * intent is that this function meets the 10-line criterion in LGPL,
  * allowing this function to be invoked directly from non-LGPL code.
  */
-static inline void _rcu_read_lock(void)
+static inline __attribute__((always_inline))
+void _rcu_read_lock(void)
 {
 	unsigned long tmp;
 
@@ -250,7 +251,8 @@ static inline void _rcu_read_unlock_update_and_wakeup(unsigned long tmp)
  * helper are smaller than 10 lines of code, and are intended to be
  * usable by non-LGPL code, as called out in LGPL.
  */
-static inline void _rcu_read_unlock(void)
+static inline __attribute__((always_inline))
+void _rcu_read_unlock(void)
 {
 	unsigned long tmp;