Commit 45f67f30 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Peter Zijlstra
Browse files

locking/rtmutex: Add a lockdep assert to catch potential nested blocking 



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: default avatarCrystal Wood <swood@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatar"Peter Zijlstra (Intel)" <peterz@infradead.org>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230908162254.999499-7-bigeasy@linutronix.de
parent d14f9e93

kernel/locking/rtmutex.c

+2 −0
Original line number Diff line number Diff line
@@ -1784,6 +1784,8 @@ 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;

kernel/locking/rwbase_rt.c

+2 −0
Original line number Diff line number Diff line
@@ -133,6 +133,8 @@ static int __sched __rwbase_read_lock(struct rwbase_rt *rwb, 
static __always_inline int rwbase_read_lock(struct rwbase_rt *rwb,

					    unsigned int state)

{

	lockdep_assert(!current->pi_blocked_on);



	if (rwbase_read_trylock(rwb))

		return 0;

kernel/locking/spinlock_rt.c

+2 −0
Original line number Diff line number Diff line
@@ -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);

}