From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
John Kacur <jkacur@redhat.com>, Julia Cartwright <julia@ni.com>,
Daniel Wagner <wagi@monom.org>, Tom Zanussi <zanussi@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: [PATCH RT 19/30] locking/rtmutex: Clean ->pi_blocked_on in the error case
Date: Thu, 23 Jan 2020 15:39:49 -0500 [thread overview]
Message-ID: <20200123203945.023629945@goodmis.org> (raw)
In-Reply-To: 20200123203930.646725253@goodmis.org
4.19.94-rt39-rc2 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Peter Zijlstra <peterz@infradead.org>
[ 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: Steven Rostedt (VMware) <rostedt@goodmis.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 2a9bf2443acc..63b3d6f306fa 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -2320,6 +2320,26 @@ 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
@@ -2392,6 +2412,9 @@ 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;
@@ -2472,7 +2495,6 @@ 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);
@@ -2484,23 +2506,8 @@ 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);
--
2.24.1
next prev parent reply other threads:[~2020-01-23 20:41 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-23 20:39 [PATCH RT 00/30] Linux 4.19.94-rt39-rc2 Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 01/30] i2c: exynos5: Remove IRQF_ONESHOT Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 02/30] i2c: hix5hd2: " Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 03/30] sched/deadline: Ensure inactive_timer runs in hardirq context Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 04/30] thermal/x86_pkg_temp: make pkg_temp_lock a raw spinlock Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 05/30] dma-buf: Use seqlock_t instread disabling preemption Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 06/30] KVM: arm/arm64: Let the timer expire in hardirq context on RT Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 07/30] x86: preempt: Check preemption level before looking at lazy-preempt Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 08/30] hrtimer: Use READ_ONCE to access timer->base in hrimer_grab_expiry_lock() Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 09/30] hrtimer: Dont grab the expiry lock for non-soft hrtimer Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 10/30] hrtimer: Prevent using hrtimer_grab_expiry_lock() on migration_base Steven Rostedt
2020-04-27 13:10 ` Rasmus Villemoes
2020-04-27 19:06 ` Steven Rostedt
2020-04-27 19:26 ` Tom Zanussi
2020-04-28 6:51 ` Rasmus Villemoes
2020-04-28 7:03 ` Rasmus Villemoes
2020-04-28 12:59 ` Tom Zanussi
2020-04-28 13:07 ` Rasmus Villemoes
2020-04-28 13:43 ` Tom Zanussi
2020-01-23 20:39 ` [PATCH RT 11/30] hrtimer: Add a missing bracket and hide `migration_base on !SMP Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 12/30] posix-timers: Unlock expiry lock in the early return Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 14/30] sched: __set_cpus_allowed_ptr: Check cpus_mask, not cpus_ptr Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 15/30] sched: Remove dead __migrate_disabled() check Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 16/30] sched: migrate disable: Protect cpus_ptr with lock Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 17/30] lib/smp_processor_id: Dont use cpumask_equal() Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 18/30] futex: Make the futex_hash_bucket spinlock_t again and bring back its old state Steven Rostedt
2020-01-23 20:39 ` Steven Rostedt [this message]
2020-01-23 20:39 ` [PATCH RT 20/30] lib/ubsan: Dont seralize UBSAN report Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 21/30] kmemleak: Change the lock of kmemleak_object to raw_spinlock_t Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 22/30] sched: migrate_enable: Use select_fallback_rq() Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 23/30] sched: Lazy migrate_disable processing Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 24/30] sched: migrate_enable: Use stop_one_cpu_nowait() Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 25/30] Revert "ARM: Initialize split page table locks for vector page" Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 26/30] locking: Make spinlock_t and rwlock_t a RCU section on RT Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 27/30] sched/core: migrate_enable() must access takedown_cpu_task on !HOTPLUG_CPU Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 28/30] lib/smp_processor_id: Adjust check_preemption_disabled() Steven Rostedt
2020-01-23 20:39 ` [PATCH RT 29/30] sched: migrate_enable: Busy loop until the migration request is completed Steven Rostedt
2020-01-23 20:40 ` [PATCH RT 30/30] Linux 4.19.94-rt39-rc2 Steven Rostedt
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