diff mbox series

[v2,4/4] locking/rtmutex: Add a lockdep assert to catch potential nested blocking

Message ID 20230427111937.2745231-5-bigeasy@linutronix.de
State New
Headers
Series locking/rtmutex: Avoid overwriting pi_blocked_on while invoking blk_flush_plug(). |

Commit Message

Sebastian Andrzej Siewior April 27, 2023, 11:19 a.m. UTC 
  From: Thomas Gleixner <tglx@linutronix.de>

There used to be a BUG_ON(current->pi_blocked_on) in the lock acquisition
functions, but that vanished in one of the rtmutex overhauls.

Bring it back in form of a lockdep assert to catch code paths which take
rtmutex based locks with current::pi_blocked_on != NULL.

Reported-by: Crystal Wood <swood@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/locking/rtmutex.c     | 2 ++
 kernel/locking/rwbase_rt.c   | 2 ++
 kernel/locking/spinlock_rt.c | 2 ++
 3 files changed, 6 insertions(+)
diff mbox series

Patch

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index dd76c1b9b7d21..479a9487edcc2 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1727,6 +1727,8 @@  static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
 static __always_inline int __rt_mutex_lock(struct rt_mutex_base *lock,
 					   unsigned int state)
 {
+	lockdep_assert(!current->pi_blocked_on);
+
 	if (likely(rt_mutex_try_acquire(lock)))
 		return 0;
 
diff --git a/kernel/locking/rwbase_rt.c b/kernel/locking/rwbase_rt.c
index 945d474f5d27f..5be92ca5afabc 100644
--- a/kernel/locking/rwbase_rt.c
+++ b/kernel/locking/rwbase_rt.c
@@ -133,6 +133,8 @@  static __always_inline int rwbase_read_lock(struct rwbase_rt *rwb,
 {
 	int ret;
 
+	lockdep_assert(!current->pi_blocked_on);
+
 	if (rwbase_read_trylock(rwb))
 		return 0;
 
diff --git a/kernel/locking/spinlock_rt.c b/kernel/locking/spinlock_rt.c
index 62c4a6866087a..9fe282cd145d9 100644
--- a/kernel/locking/spinlock_rt.c
+++ b/kernel/locking/spinlock_rt.c
@@ -37,6 +37,8 @@ 
 
 static __always_inline void rtlock_lock(struct rt_mutex_base *rtm)
 {
+	lockdep_assert(!current->pi_blocked_on);
+
 	if (unlikely(!rt_mutex_cmpxchg_acquire(rtm, NULL, current)))
 		rtlock_slowlock(rtm);
 }