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[4.4,11/11] rcu: Update documentation of rcu_read_unlock()

Message ID 20210802134624.1934-12-thunder.leizhen@huawei.com
State New
Headers show
Series Fix a potential infinite loop in RT futex-pi scenarios | expand

Commit Message

Leizhen (ThunderTown) Aug. 2, 2021, 1:46 p.m. UTC 
From: Anna-Maria Gleixner <anna-maria@linutronix.de>


[ Upstream commit ec84b27f9b3b569f9235413d1945a2006b97b0aa ]

Since commit b4abf91047cf ("rtmutex: Make wait_lock irq safe") the
explanation in rcu_read_unlock() documentation about irq unsafe rtmutex
wait_lock is no longer valid.

Remove it to prevent kernel developers reading the documentation to rely on
it.

Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>

Cc: bigeasy@linutronix.de
Link: https://lkml.kernel.org/r/20180525090507.22248-2-anna-maria@linutronix.de
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>

---
 include/linux/rcupdate.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

-- 
2.26.0.106.g9fadedd
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Patch

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 0a93e9d1708e29e..3072e9c93ae6be2 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -880,9 +880,7 @@  static __always_inline void rcu_read_lock(void)
  * Unfortunately, this function acquires the scheduler's runqueue and
  * priority-inheritance spinlocks.  This means that deadlock could result
  * if the caller of rcu_read_unlock() already holds one of these locks or
- * any lock that is ever acquired while holding them; or any lock which
- * can be taken from interrupt context because rcu_boost()->rt_mutex_lock()
- * does not disable irqs while taking ->wait_lock.
+ * any lock that is ever acquired while holding them.
  *
  * That said, RCU readers are never priority boosted unless they were
  * preempted.  Therefore, one way to avoid deadlock is to make sure