From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Juri Lelli <juri.lelli@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
Boqun Feng <boqun.feng@gmail.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Davidlohr Bueso <dave@stgolabs.net>
Subject: Re: [patch 26/50] locking/rtmutex: Provide the spin/rwlock core lock function
Date: Wed, 14 Jul 2021 12:59:24 +0200 [thread overview]
Message-ID: <20210714105924.GD2591@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20210713160748.491632534@linutronix.de>
On Tue, Jul 13, 2021 at 05:11:20PM +0200, Thomas Gleixner wrote:
> +/**
> + * rtlock_slowlock_locked - Slow path lock acquisition for RT locks
> + * @lock: The underlying rt mutex
> + */
> +static void __sched rtlock_slowlock_locked(struct rt_mutex *lock)
> +{
> + struct rt_mutex_waiter waiter;
> +
> + lockdep_assert_held(&lock->wait_lock);
> +
> + if (try_to_take_rt_mutex(lock, current, NULL))
> + return;
> +
> + rt_mutex_init_rtlock_waiter(&waiter);
> +
> + /* Save current state and set state to TASK_RTLOCK_WAIT */
> + current_save_and_set_rtlock_wait_state();
> +
> + task_blocks_on_rt_mutex(lock, &waiter, current, RT_MUTEX_MIN_CHAINWALK);
> +
> + for (;;) {
> + /* Try to acquire the lock again. */
> + if (try_to_take_rt_mutex(lock, current, &waiter))
> + break;
> +
> + raw_spin_unlock_irq(&lock->wait_lock);
> +
> + schedule_rtlock();
> +
> + raw_spin_lock_irq(&lock->wait_lock);
> + set_current_state(TASK_RTLOCK_WAIT);
Since both waker and waiter are fully serialized on ->wait_lock, this
can be __set_current_state(), there is no race condition AFAICT.
Might not be worth it though..
> + }
> +
> + /* Restore the task state */
> + current_restore_rtlock_saved_state();
> +
> + /*
> + * try_to_take_rt_mutex() sets the waiter bit unconditionally. We
> + * might have to fix that up:
> + */
> + fixup_rt_mutex_waiters(lock);
> + debug_rt_mutex_free_waiter(&waiter);
> +}
next prev parent reply other threads:[~2021-07-14 11:00 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-13 15:10 [patch 00/50] locking, sched: The PREEMPT-RT locking infrastructure Thomas Gleixner
2021-07-13 15:10 ` [patch 01/50] sched: Split out the wakeup state check Thomas Gleixner
2021-07-13 15:10 ` [patch 02/50] sched: Introduce TASK_RTLOCK_WAIT Thomas Gleixner
2021-07-13 15:10 ` [patch 03/50] sched: Prepare for RT sleeping spin/rwlocks Thomas Gleixner
2021-07-13 19:52 ` Waiman Long
2021-07-14 23:20 ` Valentin Schneider
2021-07-15 9:27 ` Peter Zijlstra
2021-07-15 14:08 ` Valentin Schneider
2021-07-13 15:10 ` [patch 04/50] sched: Rework the __schedule() preempt argument Thomas Gleixner
2021-07-13 20:04 ` Waiman Long
2021-07-13 15:10 ` [patch 05/50] sched: Provide schedule point for RT locks Thomas Gleixner
2021-07-14 8:28 ` Peter Zijlstra
2021-07-14 9:49 ` Thomas Gleixner
2021-07-14 10:17 ` Peter Zijlstra
2021-07-14 11:32 ` Thomas Gleixner
2021-07-13 15:11 ` [patch 06/50] sched/wake_q: Provide WAKE_Q_HEAD_INITIALIZER Thomas Gleixner
2021-07-13 15:11 ` [patch 07/50] rtmutex: Convert macros to inlines Thomas Gleixner
2021-07-13 15:11 ` [patch 08/50] rtmutex: Switch to try_cmpxchg() Thomas Gleixner
2021-07-13 15:11 ` [patch 09/50] rtmutex: Split API and implementation Thomas Gleixner
2021-07-13 15:11 ` [patch 10/50] locking/rtmutex: Provide rt_mutex_slowlock_locked() Thomas Gleixner
2021-07-27 17:20 ` Valentin Schneider
2021-07-27 19:02 ` Thomas Gleixner
2021-07-13 15:11 ` [patch 11/50] locking/rtmutex: Provide lockdep less variants of rtmutex interfaces Thomas Gleixner
2021-07-13 15:11 ` [patch 12/50] locking: Add base code for RT rw_semaphore and rwlock Thomas Gleixner
2021-07-13 15:11 ` [patch 13/50] locking/rwsem: Add rtmutex based R/W semaphore implementation Thomas Gleixner
2021-07-13 15:11 ` [patch 14/50] locking/rtmutex: Add wake_state to rt_mutex_waiter Thomas Gleixner
2021-07-14 10:18 ` Peter Zijlstra
2021-07-14 11:33 ` Thomas Gleixner
2021-07-13 15:11 ` [patch 15/50] locking/rtmutex: Provide rt_mutex_wake_q and helpers Thomas Gleixner
2021-07-13 15:11 ` [patch 16/50] locking/rtmutex: Use rt_mutex_wake_q_head Thomas Gleixner
2021-07-14 8:55 ` Peter Zijlstra
2021-07-14 9:51 ` Thomas Gleixner
2021-07-13 15:11 ` [patch 17/50] locking/rtmutex: Prepare RT rt_mutex_wake_q for RT locks Thomas Gleixner
2021-07-14 8:55 ` Peter Zijlstra
2021-07-14 9:52 ` Thomas Gleixner
2021-07-13 15:11 ` [patch 18/50] locking/rtmutex: Guard regular sleeping locks specific functions Thomas Gleixner
2021-07-13 15:11 ` [patch 19/50] locking/spinlock: Split the lock types header Thomas Gleixner
2021-07-13 15:11 ` [patch 20/50] locking/rtmutex: Prevent future include recursion hell Thomas Gleixner
2021-07-13 15:11 ` [patch 21/50] locking/lockdep: Reduce includes in debug_locks.h Thomas Gleixner
2021-07-13 15:11 ` [patch 22/50] rbtree: Split out the rbtree type definitions Thomas Gleixner
2021-07-14 9:24 ` Peter Zijlstra
2021-07-14 9:31 ` Arnaldo
2021-07-13 15:11 ` [patch 23/50] locking/rtmutex: Include only rbtree types Thomas Gleixner
2021-07-13 15:11 ` [patch 24/50] locking/spinlock: Provide RT specific spinlock type Thomas Gleixner
2021-07-14 9:54 ` Peter Zijlstra
2021-07-14 10:07 ` [PATCH] media/atomisp: Use lockdep instead of *mutex_is_locked() Peter Zijlstra
2021-07-13 15:11 ` [patch 25/50] locking/spinlock: Provide RT variant header Thomas Gleixner
2021-07-13 15:11 ` [patch 26/50] locking/rtmutex: Provide the spin/rwlock core lock function Thomas Gleixner
2021-07-14 10:59 ` Peter Zijlstra [this message]
2021-07-13 15:11 ` [patch 27/50] locking/spinlock: Provide RT variant Thomas Gleixner
2021-07-14 11:25 ` Peter Zijlstra
2021-07-13 15:11 ` [patch 28/50] locking/rwlock: " Thomas Gleixner
2021-07-13 15:11 ` [patch 29/50] locking/mutex: Consolidate core headers Thomas Gleixner
2021-07-13 15:11 ` [patch 30/50] locking/mutex: Move waiter to core header Thomas Gleixner
2021-07-13 15:11 ` [patch 31/50] locking/ww_mutex: Move ww_mutex declarations into ww_mutex.h Thomas Gleixner
2021-07-13 15:11 ` [patch 32/50] locking/mutex: Make mutex::wait_lock raw Thomas Gleixner
2021-07-13 15:11 ` [patch 33/50] locking/mutex: Introduce _mutex_t Thomas Gleixner
2021-07-15 17:31 ` Peter Zijlstra
2021-07-13 15:11 ` [patch 34/50] locking/mutex: Rename the ww_mutex relevant functions Thomas Gleixner
2021-07-13 15:11 ` [patch 35/50] locking/ww_mutex: Switch to _mutex_t Thomas Gleixner
2021-07-13 15:11 ` [patch 36/50] locking/mutex: Replace struct mutex in core code Thomas Gleixner
2021-07-13 15:11 ` [patch 37/50] locking/mutex: Rearrange items in mutex.h Thomas Gleixner
2021-07-13 15:11 ` [patch 38/50] locking/mutex: Exclude non-ww_mutex API for RT Thomas Gleixner
2021-07-13 15:11 ` [patch 39/50] locking/rtmutex: Add mutex variant " Thomas Gleixner
2021-07-13 15:11 ` [patch 40/50] lib/test_lockup: Adapt to changed variables Thomas Gleixner
2021-07-13 15:11 ` [patch 41/50] futex: Validate waiter correctly in futex_proxy_trylock_atomic() Thomas Gleixner
2021-07-13 15:11 ` [patch 42/50] futex: Cleanup stale comments Thomas Gleixner
2021-07-28 23:28 ` André Almeida
2021-07-13 15:11 ` [patch 43/50] futex: Correct the number of requeued waiters for PI Thomas Gleixner
2021-07-13 15:11 ` [patch 44/50] futex: Restructure futex_requeue() Thomas Gleixner
2021-07-13 15:11 ` [patch 45/50] futex: Clarify comment in futex_requeue() Thomas Gleixner
2021-07-13 15:11 ` [patch 46/50] futex: Prevent requeue_pi() lock nesting issue on RT Thomas Gleixner
2021-07-13 15:11 ` [patch 47/50] rtmutex: Prevent lockdep false positive with PI futexes Thomas Gleixner
2021-07-13 15:11 ` [patch 48/50] preempt: Adjust PREEMPT_LOCK_OFFSET for RT Thomas Gleixner
2021-07-13 15:11 ` [patch 49/50] locking/rtmutex: Implement equal priority lock stealing Thomas Gleixner
2021-07-13 15:11 ` [patch 50/50] locking/rtmutex: Add adaptive spinwait mechanism Thomas Gleixner
2021-07-27 17:19 ` [patch 00/50] locking, sched: The PREEMPT-RT locking infrastructure Valentin Schneider
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