diff options
| author |   Thomas Gleixner <tglx@linutronix.de> | 2021-08-15 23:28:11 +0200 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2021-08-17 17:21:09 +0200 |
| commit | 456cfbc65cd072f4f53936ee5a37eb1447a7d3ba (patch) | |
| tree | b567f3f01eebfe206b5f355d5f9941a38fbee88c /kernel/locking | |
| parent | locking/rtmutex: Use rt_mutex_wake_q_head (diff) | |
| download | linux-dev-456cfbc65cd072f4f53936ee5a37eb1447a7d3ba.tar.xz linux-dev-456cfbc65cd072f4f53936ee5a37eb1447a7d3ba.zip | |
locking/rtmutex: Prepare RT rt_mutex_wake_q for RT locks
Add an rtlock_task pointer to rt_mutex_wake_q, which allows to handle the RT
specific wakeup for spin/rwlock waiters. The pointer is just consuming 4/8
bytes on the stack so it is provided unconditionaly to avoid #ifdeffery all
over the place.
This cannot use a regular wake_q, because a task can have concurrent wakeups which
would make it miss either lock or the regular wakeups, depending on what gets
queued first, unless task struct gains a separate wake_q_node for this, which
would be overkill, because there can only be a single task which gets woken
up in the spin/rw_lock unlock path.
No functional change for non-RT enabled kernels.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211303.253614678@linutronix.de
Diffstat (limited to 'kernel/locking')
| -rw-r--r-- | kernel/locking/rtmutex.c | 18 | ||||
| -rw-r--r-- | kernel/locking/rtmutex_common.h | 5 |
2 files changed, 20 insertions, 3 deletions
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 5f0d0725ca32..8b0d38dc4147 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -351,12 +351,26 @@ static __always_inline void rt_mutex_adjust_prio(struct task_struct *p) static __always_inline void rt_mutex_wake_q_add(struct rt_wake_q_head *wqh, struct rt_mutex_waiter *w) { - wake_q_add(&wqh->head, w->task); + if (IS_ENABLED(CONFIG_PREEMPT_RT) && w->wake_state != TASK_NORMAL) { + if (IS_ENABLED(CONFIG_PROVE_LOCKING)) + WARN_ON_ONCE(wqh->rtlock_task); + get_task_struct(w->task); + wqh->rtlock_task = w->task; + } else { + wake_q_add(&wqh->head, w->task); + } } static __always_inline void rt_mutex_wake_up_q(struct rt_wake_q_head *wqh) { - wake_up_q(&wqh->head); + if (IS_ENABLED(CONFIG_PREEMPT_RT) && wqh->rtlock_task) { + wake_up_state(wqh->rtlock_task, TASK_RTLOCK_WAIT); + put_task_struct(wqh->rtlock_task); + wqh->rtlock_task = NULL; + } + + if (!wake_q_empty(&wqh->head)) + wake_up_q(&wqh->head); /* Pairs with preempt_disable() in mark_wakeup_next_waiter() */ preempt_enable(); diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h index ff36316003d8..424ee0f5e5a4 100644 --- a/kernel/locking/rtmutex_common.h +++ b/kernel/locking/rtmutex_common.h @@ -42,15 +42,18 @@ struct rt_mutex_waiter { /** * rt_wake_q_head - Wrapper around regular wake_q_head to support * "sleeping" spinlocks on RT - * @head: The regular wake_q_head for sleeping lock variants + * @head: The regular wake_q_head for sleeping lock variants + * @rtlock_task: Task pointer for RT lock (spin/rwlock) wakeups */ struct rt_wake_q_head { struct wake_q_head head; + struct task_struct *rtlock_task; }; #define DEFINE_RT_WAKE_Q(name) \ struct rt_wake_q_head name = { \ .head = WAKE_Q_HEAD_INITIALIZER(name.head), \ + .rtlock_task = NULL, \ } /* |