Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU changes from Ingo Molar: "The main changes: - torture-test updates - callback-offloading changes - maintainership changes - update RCU documentation - miscellaneous fixes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits) rcu: Allow for NULL tick_nohz_full_mask when nohz_full= missing rcu: Fix a sparse warning in rcu_report_unblock_qs_rnp() rcu: Fix a sparse warning in rcu_initiate_boost() rcu: Fix __rcu_reclaim() to use true/false for bool rcu: Remove CONFIG_PROVE_RCU_DELAY rcu: Use __this_cpu_read() instead of per_cpu_ptr() rcu: Don't use NMIs to dump other CPUs' stacks rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs rcu: Simplify priority boosting by putting rt_mutex in rcu_node rcu: Check both root and current rcu_node when setting up future grace period rcu: Allow post-unlock reference for rt_mutex rcu: Loosen __call_rcu()'s rcu_head alignment constraint rcu: Eliminate read-modify-write ACCESS_ONCE() calls rcu: Remove redundant ACCESS_ONCE() from tick_do_timer_cpu rcu: Make rcu node arrays static const char * const signal: Explain local_irq_save() call rcu: Handle obsolete references to TINY_PREEMPT_RCU rcu: Document deadlock-avoidance information for rcu_read_unlock() scripts: Teach get_maintainer.pl about the new "R:" tag rcu: Update rcu torture maintainership filename patterns ...
This commit is contained in:
Linus Torvalds
commit
5bda4f638f
40 changed files with 491 additions and 176 deletions
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@ -102,12 +102,6 @@ extern struct group_info init_groups;
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#define INIT_IDS
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#endif
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#ifdef CONFIG_RCU_BOOST
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#define INIT_TASK_RCU_BOOST() \
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.rcu_boost_mutex = NULL,
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#else
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#define INIT_TASK_RCU_BOOST()
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#endif
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#ifdef CONFIG_TREE_PREEMPT_RCU
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#define INIT_TASK_RCU_TREE_PREEMPT() \
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.rcu_blocked_node = NULL,
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@ -119,8 +113,7 @@ extern struct group_info init_groups;
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.rcu_read_lock_nesting = 0, \
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.rcu_read_unlock_special = 0, \
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.rcu_node_entry = LIST_HEAD_INIT(tsk.rcu_node_entry), \
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INIT_TASK_RCU_TREE_PREEMPT() \
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INIT_TASK_RCU_BOOST()
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INIT_TASK_RCU_TREE_PREEMPT()
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#else
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#define INIT_TASK_RCU_PREEMPT(tsk)
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#endif
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@ -826,15 +826,14 @@ static inline void rcu_preempt_sleep_check(void)
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* read-side critical section that would block in a !PREEMPT kernel.
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* But if you want the full story, read on!
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*
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* In non-preemptible RCU implementations (TREE_RCU and TINY_RCU), it
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* is illegal to block while in an RCU read-side critical section. In
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* preemptible RCU implementations (TREE_PREEMPT_RCU and TINY_PREEMPT_RCU)
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* in CONFIG_PREEMPT kernel builds, RCU read-side critical sections may
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* be preempted, but explicit blocking is illegal. Finally, in preemptible
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* RCU implementations in real-time (with -rt patchset) kernel builds,
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* RCU read-side critical sections may be preempted and they may also
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* block, but only when acquiring spinlocks that are subject to priority
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* inheritance.
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* In non-preemptible RCU implementations (TREE_RCU and TINY_RCU),
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* it is illegal to block while in an RCU read-side critical section.
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* In preemptible RCU implementations (TREE_PREEMPT_RCU) in CONFIG_PREEMPT
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* kernel builds, RCU read-side critical sections may be preempted,
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* but explicit blocking is illegal. Finally, in preemptible RCU
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* implementations in real-time (with -rt patchset) kernel builds, RCU
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* read-side critical sections may be preempted and they may also block, but
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* only when acquiring spinlocks that are subject to priority inheritance.
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*/
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static inline void rcu_read_lock(void)
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{
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@ -858,6 +857,34 @@ static inline void rcu_read_lock(void)
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/**
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* rcu_read_unlock() - marks the end of an RCU read-side critical section.
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*
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* In most situations, rcu_read_unlock() is immune from deadlock.
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* However, in kernels built with CONFIG_RCU_BOOST, rcu_read_unlock()
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* is responsible for deboosting, which it does via rt_mutex_unlock().
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* Unfortunately, this function acquires the scheduler's runqueue and
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* priority-inheritance spinlocks. This means that deadlock could result
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* if the caller of rcu_read_unlock() already holds one of these locks or
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* any lock that is ever acquired while holding them.
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*
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* That said, RCU readers are never priority boosted unless they were
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* preempted. Therefore, one way to avoid deadlock is to make sure
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* that preemption never happens within any RCU read-side critical
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* section whose outermost rcu_read_unlock() is called with one of
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* rt_mutex_unlock()'s locks held. Such preemption can be avoided in
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* a number of ways, for example, by invoking preempt_disable() before
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* critical section's outermost rcu_read_lock().
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*
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* Given that the set of locks acquired by rt_mutex_unlock() might change
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* at any time, a somewhat more future-proofed approach is to make sure
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* that that preemption never happens within any RCU read-side critical
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* section whose outermost rcu_read_unlock() is called with irqs disabled.
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* This approach relies on the fact that rt_mutex_unlock() currently only
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* acquires irq-disabled locks.
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*
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* The second of these two approaches is best in most situations,
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* however, the first approach can also be useful, at least to those
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* developers willing to keep abreast of the set of locks acquired by
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* rt_mutex_unlock().
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*
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* See rcu_read_lock() for more information.
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*/
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static inline void rcu_read_unlock(void)
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@ -1270,9 +1270,6 @@ struct task_struct {
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#ifdef CONFIG_TREE_PREEMPT_RCU
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struct rcu_node *rcu_blocked_node;
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#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
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#ifdef CONFIG_RCU_BOOST
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struct rt_mutex *rcu_boost_mutex;
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#endif /* #ifdef CONFIG_RCU_BOOST */
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#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
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struct sched_info sched_info;
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@ -2009,9 +2006,6 @@ static inline void rcu_copy_process(struct task_struct *p)
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#ifdef CONFIG_TREE_PREEMPT_RCU
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p->rcu_blocked_node = NULL;
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#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
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#ifdef CONFIG_RCU_BOOST
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p->rcu_boost_mutex = NULL;
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#endif /* #ifdef CONFIG_RCU_BOOST */
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INIT_LIST_HEAD(&p->rcu_node_entry);
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}
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@ -12,6 +12,7 @@
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#include <linux/hrtimer.h>
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#include <linux/context_tracking_state.h>
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#include <linux/cpumask.h>
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#include <linux/sched.h>
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#ifdef CONFIG_GENERIC_CLOCKEVENTS
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@ -162,6 +163,7 @@ static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
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#ifdef CONFIG_NO_HZ_FULL
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extern bool tick_nohz_full_running;
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extern cpumask_var_t tick_nohz_full_mask;
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extern cpumask_var_t housekeeping_mask;
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static inline bool tick_nohz_full_enabled(void)
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{
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@ -194,6 +196,24 @@ static inline void tick_nohz_full_kick_all(void) { }
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static inline void __tick_nohz_task_switch(struct task_struct *tsk) { }
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#endif
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static inline bool is_housekeeping_cpu(int cpu)
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{
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#ifdef CONFIG_NO_HZ_FULL
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if (tick_nohz_full_enabled())
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return cpumask_test_cpu(cpu, housekeeping_mask);
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#endif
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return true;
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}
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static inline void housekeeping_affine(struct task_struct *t)
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{
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#ifdef CONFIG_NO_HZ_FULL
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if (tick_nohz_full_enabled())
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set_cpus_allowed_ptr(t, housekeeping_mask);
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#endif
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}
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static inline void tick_nohz_full_check(void)
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{
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if (tick_nohz_full_enabled())
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