From: zanussi@kernel.org
To: LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>, John Kacur <jkacur@redhat.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Daniel Wagner <wagi@monom.org>, Tom Zanussi <zanussi@kernel.org>
Subject: [PATCH RT 12/25] locking/rtmutex: Clean ->pi_blocked_on in the error case
Date: Fri, 21 Feb 2020 15:24:40 -0600 [thread overview]
Message-ID: <befe685be1d8f3710d33ee259b869645117d2138.1582320278.git.zanussi@kernel.org> (raw)
In-Reply-To: <cover.1582320278.git.zanussi@kernel.org>
In-Reply-To: <cover.1582320278.git.zanussi@kernel.org>
From: Peter Zijlstra <peterz@infradead.org>
v4.14.170-rt75-rc1 stable review patch.
If anyone has any objections, please let me know.
-----------
[ Upstream commit 0be4ea6e3ce693101be0fbd55a0cc7ce238ab2eb ]
The function rt_mutex_wait_proxy_lock() cleans ->pi_blocked_on in case
of failure (timeout, signal). The same cleanup is required in
__rt_mutex_start_proxy_lock().
In both the cases the tasks was interrupted by a signal or timeout while
acquiring the lock and after the interruption it longer blocks on the
lock.
Fixes: 1a1fb985f2e2b ("futex: Handle early deadlock return correctly")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
---
kernel/locking/rtmutex.c | 43 +++++++++++++++++++++++++------------------
1 file changed, 25 insertions(+), 18 deletions(-)
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 1177f2815040..4bc01a2a9a88 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -2328,6 +2328,26 @@ void rt_mutex_proxy_unlock(struct rt_mutex *lock,
rt_mutex_set_owner(lock, NULL);
}
+static void fixup_rt_mutex_blocked(struct rt_mutex *lock)
+{
+ struct task_struct *tsk = current;
+ /*
+ * RT has a problem here when the wait got interrupted by a timeout
+ * or a signal. task->pi_blocked_on is still set. The task must
+ * acquire the hash bucket lock when returning from this function.
+ *
+ * If the hash bucket lock is contended then the
+ * BUG_ON(rt_mutex_real_waiter(task->pi_blocked_on)) in
+ * task_blocks_on_rt_mutex() will trigger. This can be avoided by
+ * clearing task->pi_blocked_on which removes the task from the
+ * boosting chain of the rtmutex. That's correct because the task
+ * is not longer blocked on it.
+ */
+ raw_spin_lock(&tsk->pi_lock);
+ tsk->pi_blocked_on = NULL;
+ raw_spin_unlock(&tsk->pi_lock);
+}
+
/**
* __rt_mutex_start_proxy_lock() - Start lock acquisition for another task
* @lock: the rt_mutex to take
@@ -2400,6 +2420,9 @@ int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
ret = 0;
}
+ if (ret)
+ fixup_rt_mutex_blocked(lock);
+
debug_rt_mutex_print_deadlock(waiter);
return ret;
@@ -2480,7 +2503,6 @@ int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
struct hrtimer_sleeper *to,
struct rt_mutex_waiter *waiter)
{
- struct task_struct *tsk = current;
int ret;
raw_spin_lock_irq(&lock->wait_lock);
@@ -2492,23 +2514,8 @@ int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
* have to fix that up.
*/
fixup_rt_mutex_waiters(lock);
- /*
- * RT has a problem here when the wait got interrupted by a timeout
- * or a signal. task->pi_blocked_on is still set. The task must
- * acquire the hash bucket lock when returning from this function.
- *
- * If the hash bucket lock is contended then the
- * BUG_ON(rt_mutex_real_waiter(task->pi_blocked_on)) in
- * task_blocks_on_rt_mutex() will trigger. This can be avoided by
- * clearing task->pi_blocked_on which removes the task from the
- * boosting chain of the rtmutex. That's correct because the task
- * is not longer blocked on it.
- */
- if (ret) {
- raw_spin_lock(&tsk->pi_lock);
- tsk->pi_blocked_on = NULL;
- raw_spin_unlock(&tsk->pi_lock);
- }
+ if (ret)
+ fixup_rt_mutex_blocked(lock);
raw_spin_unlock_irq(&lock->wait_lock);
--
2.14.1
next prev parent reply other threads:[~2020-02-21 21:25 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 21:24 [PATCH RT 00/25] Linux v4.14.170-rt75-rc1 zanussi
2020-02-21 21:24 ` [PATCH RT 01/25] Fix wrong-variable use in irq_set_affinity_notifier zanussi
2020-02-21 21:24 ` [PATCH RT 02/25] x86: preempt: Check preemption level before looking at lazy-preempt zanussi
2020-02-21 21:24 ` [PATCH RT 03/25] sched/deadline: Ensure inactive_timer runs in hardirq context zanussi
2020-02-24 8:33 ` Sebastian Andrzej Siewior
2020-02-25 14:50 ` Juri Lelli
2020-02-21 21:24 ` [PATCH RT 04/25] i2c: hix5hd2: Remove IRQF_ONESHOT zanussi
2020-02-21 21:24 ` [PATCH RT 05/25] i2c: exynos5: " zanussi
2020-02-21 21:24 ` [PATCH RT 06/25] sched: migrate_dis/enable: Use sleeping_lock…() to annotate sleeping points zanussi
2020-02-21 21:24 ` [PATCH RT 07/25] sched: __set_cpus_allowed_ptr: Check cpus_mask, not cpus_ptr zanussi
2020-02-21 21:24 ` [PATCH RT 08/25] sched: Remove dead __migrate_disabled() check zanussi
2020-02-21 21:24 ` [PATCH RT 09/25] sched: migrate disable: Protect cpus_ptr with lock zanussi
2020-02-21 21:24 ` [PATCH RT 10/25] lib/smp_processor_id: Don't use cpumask_equal() zanussi
2020-02-21 21:24 ` [PATCH RT 11/25] futex: Make the futex_hash_bucket spinlock_t again and bring back its old state zanussi
2020-02-21 21:24 ` zanussi [this message]
2020-02-21 21:24 ` [PATCH RT 13/25] lib/ubsan: Don't seralize UBSAN report zanussi
2020-02-21 21:24 ` [PATCH RT 14/25] kmemleak: Change the lock of kmemleak_object to raw_spinlock_t zanussi
2020-02-21 21:24 ` [PATCH RT 15/25] sched: migrate_enable: Use select_fallback_rq() zanussi
2020-02-24 9:43 ` Sebastian Andrzej Siewior
2020-02-24 15:31 ` Tom Zanussi
2020-02-24 16:05 ` Sebastian Andrzej Siewior
2020-02-24 22:15 ` Scott Wood
2020-02-21 21:24 ` [PATCH RT 16/25] Revert "ARM: Initialize split page table locks for vector page" zanussi
2020-02-21 21:24 ` [PATCH RT 17/25] x86/fpu: Don't cache access to fpu_fpregs_owner_ctx zanussi
2020-02-24 8:55 ` Sebastian Andrzej Siewior
2020-02-24 15:12 ` Tom Zanussi
2020-02-21 21:24 ` [PATCH RT 18/25] locking: Make spinlock_t and rwlock_t a RCU section on RT zanussi
2020-02-21 21:24 ` [PATCH RT 19/25] userfaultfd: Use a seqlock instead of seqcount zanussi
2020-02-24 9:03 ` Sebastian Andrzej Siewior
2020-02-24 15:14 ` Tom Zanussi
2020-02-24 16:17 ` Steven Rostedt
2020-02-21 21:24 ` [PATCH RT 20/25] kmemleak: Cosmetic changes zanussi
2020-02-24 9:12 ` Sebastian Andrzej Siewior
2020-02-24 15:18 ` Tom Zanussi
2020-02-24 15:52 ` Sebastian Andrzej Siewior
2020-02-21 21:24 ` [PATCH RT 21/25] smp: Use smp_cond_func_t as type for the conditional function zanussi
2020-02-24 9:52 ` Sebastian Andrzej Siewior
2020-02-24 15:34 ` Tom Zanussi
2020-02-21 21:24 ` [PATCH RT 22/25] mm/memcontrol: Move misplaced local_unlock_irqrestore() zanussi
2020-02-24 9:55 ` Sebastian Andrzej Siewior
2020-02-21 21:24 ` [PATCH RT 23/25] locallock: Include header for the `current' macro zanussi
2020-02-21 21:24 ` [PATCH RT 24/25] sched: Provide migrate_disable/enable() inlines zanussi
2020-02-21 21:24 ` [PATCH RT 25/25] Linux 4.14.170-rt75-rc1 zanussi
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