diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 41 | ||||
| -rw-r--r-- | kernel/locking/rtmutex.c | 12 | ||||
| -rw-r--r-- | kernel/sched/core.c | 54 | ||||
| -rw-r--r-- | kernel/watchdog.c | 20 |
4 files changed, 81 insertions, 46 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 81aa3a4ece9f..1a3bf48743ce 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -913,10 +913,30 @@ static void put_ctx(struct perf_event_context *ctx) * Those places that change perf_event::ctx will hold both * perf_event_ctx::mutex of the 'old' and 'new' ctx value. * - * Lock ordering is by mutex address. There is one other site where - * perf_event_context::mutex nests and that is put_event(). But remember that - * that is a parent<->child context relation, and migration does not affect - * children, therefore these two orderings should not interact. + * Lock ordering is by mutex address. There are two other sites where + * perf_event_context::mutex nests and those are: + * + * - perf_event_exit_task_context() [ child , 0 ] + * __perf_event_exit_task() + * sync_child_event() + * put_event() [ parent, 1 ] + * + * - perf_event_init_context() [ parent, 0 ] + * inherit_task_group() + * inherit_group() + * inherit_event() + * perf_event_alloc() + * perf_init_event() + * perf_try_init_event() [ child , 1 ] + * + * While it appears there is an obvious deadlock here -- the parent and child + * nesting levels are inverted between the two. This is in fact safe because + * life-time rules separate them. That is an exiting task cannot fork, and a + * spawning task cannot (yet) exit. + * + * But remember that that these are parent<->child context relations, and + * migration does not affect children, therefore these two orderings should not + * interact. * * The change in perf_event::ctx does not affect children (as claimed above) * because the sys_perf_event_open() case will install a new event and break @@ -3657,9 +3677,6 @@ static void perf_remove_from_owner(struct perf_event *event) } } -/* - * Called when the last reference to the file is gone. - */ static void put_event(struct perf_event *event) { struct perf_event_context *ctx; @@ -3697,6 +3714,9 @@ int perf_event_release_kernel(struct perf_event *event) } EXPORT_SYMBOL_GPL(perf_event_release_kernel); +/* + * Called when the last reference to the file is gone. + */ static int perf_release(struct inode *inode, struct file *file) { put_event(file->private_data); @@ -7364,7 +7384,12 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event) return -ENODEV; if (event->group_leader != event) { - ctx = perf_event_ctx_lock(event->group_leader); + /* + * This ctx->mutex can nest when we're called through + * inheritance. See the perf_event_ctx_lock_nested() comment. + */ + ctx = perf_event_ctx_lock_nested(event->group_leader, + SINGLE_DEPTH_NESTING); BUG_ON(!ctx); } diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index b73279367087..b025295f4966 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -265,15 +265,17 @@ struct task_struct *rt_mutex_get_top_task(struct task_struct *task) } /* - * Called by sched_setscheduler() to check whether the priority change - * is overruled by a possible priority boosting. + * Called by sched_setscheduler() to get the priority which will be + * effective after the change. */ -int rt_mutex_check_prio(struct task_struct *task, int newprio) +int rt_mutex_get_effective_prio(struct task_struct *task, int newprio) { if (!task_has_pi_waiters(task)) - return 0; + return newprio; - return task_top_pi_waiter(task)->task->prio <= newprio; + if (task_top_pi_waiter(task)->task->prio <= newprio) + return task_top_pi_waiter(task)->task->prio; + return newprio; } /* diff --git a/kernel/sched/core.c b/kernel/sched/core.c index cfeebb499e79..123673291ffb 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3300,15 +3300,18 @@ static void __setscheduler_params(struct task_struct *p, /* Actually do priority change: must hold pi & rq lock. */ static void __setscheduler(struct rq *rq, struct task_struct *p, - const struct sched_attr *attr) + const struct sched_attr *attr, bool keep_boost) { __setscheduler_params(p, attr); /* - * If we get here, there was no pi waiters boosting the - * task. It is safe to use the normal prio. + * Keep a potential priority boosting if called from + * sched_setscheduler(). */ - p->prio = normal_prio(p); + if (keep_boost) + p->prio = rt_mutex_get_effective_prio(p, normal_prio(p)); + else + p->prio = normal_prio(p); if (dl_prio(p->prio)) p->sched_class = &dl_sched_class; @@ -3408,7 +3411,7 @@ static int __sched_setscheduler(struct task_struct *p, int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 : MAX_RT_PRIO - 1 - attr->sched_priority; int retval, oldprio, oldpolicy = -1, queued, running; - int policy = attr->sched_policy; + int new_effective_prio, policy = attr->sched_policy; unsigned long flags; const struct sched_class *prev_class; struct rq *rq; @@ -3590,15 +3593,14 @@ change: oldprio = p->prio; /* - * Special case for priority boosted tasks. - * - * If the new priority is lower or equal (user space view) - * than the current (boosted) priority, we just store the new + * Take priority boosted tasks into account. If the new + * effective priority is unchanged, we just store the new * normal parameters and do not touch the scheduler class and * the runqueue. This will be done when the task deboost * itself. */ - if (rt_mutex_check_prio(p, newprio)) { + new_effective_prio = rt_mutex_get_effective_prio(p, newprio); + if (new_effective_prio == oldprio) { __setscheduler_params(p, attr); task_rq_unlock(rq, p, &flags); return 0; @@ -3612,7 +3614,7 @@ change: put_prev_task(rq, p); prev_class = p->sched_class; - __setscheduler(rq, p, attr); + __setscheduler(rq, p, attr, true); if (running) p->sched_class->set_curr_task(rq); @@ -6994,27 +6996,23 @@ static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, unsigned long flags; long cpu = (long)hcpu; struct dl_bw *dl_b; + bool overflow; + int cpus; - switch (action & ~CPU_TASKS_FROZEN) { + switch (action) { case CPU_DOWN_PREPARE: - /* explicitly allow suspend */ - if (!(action & CPU_TASKS_FROZEN)) { - bool overflow; - int cpus; - - rcu_read_lock_sched(); - dl_b = dl_bw_of(cpu); + rcu_read_lock_sched(); + dl_b = dl_bw_of(cpu); - raw_spin_lock_irqsave(&dl_b->lock, flags); - cpus = dl_bw_cpus(cpu); - overflow = __dl_overflow(dl_b, cpus, 0, 0); - raw_spin_unlock_irqrestore(&dl_b->lock, flags); + raw_spin_lock_irqsave(&dl_b->lock, flags); + cpus = dl_bw_cpus(cpu); + overflow = __dl_overflow(dl_b, cpus, 0, 0); + raw_spin_unlock_irqrestore(&dl_b->lock, flags); - rcu_read_unlock_sched(); + rcu_read_unlock_sched(); - if (overflow) - return notifier_from_errno(-EBUSY); - } + if (overflow) + return notifier_from_errno(-EBUSY); cpuset_update_active_cpus(false); break; case CPU_DOWN_PREPARE_FROZEN: @@ -7343,7 +7341,7 @@ static void normalize_task(struct rq *rq, struct task_struct *p) queued = task_on_rq_queued(p); if (queued) dequeue_task(rq, p, 0); - __setscheduler(rq, p, &attr); + __setscheduler(rq, p, &attr, false); if (queued) { enqueue_task(rq, p, 0); resched_curr(rq); diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 2316f50b07a4..581a68a04c64 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -41,6 +41,8 @@ #define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT) #define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT) +static DEFINE_MUTEX(watchdog_proc_mutex); + #ifdef CONFIG_HARDLOCKUP_DETECTOR static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED; #else @@ -608,26 +610,36 @@ void watchdog_nmi_enable_all(void) { int cpu; - if (!watchdog_user_enabled) - return; + mutex_lock(&watchdog_proc_mutex); + + if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) + goto unlock; get_online_cpus(); for_each_online_cpu(cpu) watchdog_nmi_enable(cpu); put_online_cpus(); + +unlock: + mutex_unlock(&watchdog_proc_mutex); } void watchdog_nmi_disable_all(void) { int cpu; + mutex_lock(&watchdog_proc_mutex); + if (!watchdog_running) - return; + goto unlock; get_online_cpus(); for_each_online_cpu(cpu) watchdog_nmi_disable(cpu); put_online_cpus(); + +unlock: + mutex_unlock(&watchdog_proc_mutex); } #else static int watchdog_nmi_enable(unsigned int cpu) { return 0; } @@ -744,8 +756,6 @@ static int proc_watchdog_update(void) } -static DEFINE_MUTEX(watchdog_proc_mutex); - /* * common function for watchdog, nmi_watchdog and soft_watchdog parameter * |