Merge tag 'staging-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh...
[platform/kernel/linux-starfive.git] / kernel / irq_work.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2010 Red Hat, Inc., Peter Zijlstra
4  *
5  * Provides a framework for enqueueing and running callbacks from hardirq
6  * context. The enqueueing is NMI-safe.
7  */
8
9 #include <linux/bug.h>
10 #include <linux/kernel.h>
11 #include <linux/export.h>
12 #include <linux/irq_work.h>
13 #include <linux/percpu.h>
14 #include <linux/hardirq.h>
15 #include <linux/irqflags.h>
16 #include <linux/sched.h>
17 #include <linux/tick.h>
18 #include <linux/cpu.h>
19 #include <linux/notifier.h>
20 #include <linux/smp.h>
21 #include <linux/smpboot.h>
22 #include <asm/processor.h>
23 #include <linux/kasan.h>
24
25 static DEFINE_PER_CPU(struct llist_head, raised_list);
26 static DEFINE_PER_CPU(struct llist_head, lazy_list);
27 static DEFINE_PER_CPU(struct task_struct *, irq_workd);
28
29 static void wake_irq_workd(void)
30 {
31         struct task_struct *tsk = __this_cpu_read(irq_workd);
32
33         if (!llist_empty(this_cpu_ptr(&lazy_list)) && tsk)
34                 wake_up_process(tsk);
35 }
36
37 #ifdef CONFIG_SMP
38 static void irq_work_wake(struct irq_work *entry)
39 {
40         wake_irq_workd();
41 }
42
43 static DEFINE_PER_CPU(struct irq_work, irq_work_wakeup) =
44         IRQ_WORK_INIT_HARD(irq_work_wake);
45 #endif
46
47 static int irq_workd_should_run(unsigned int cpu)
48 {
49         return !llist_empty(this_cpu_ptr(&lazy_list));
50 }
51
52 /*
53  * Claim the entry so that no one else will poke at it.
54  */
55 static bool irq_work_claim(struct irq_work *work)
56 {
57         int oflags;
58
59         oflags = atomic_fetch_or(IRQ_WORK_CLAIMED | CSD_TYPE_IRQ_WORK, &work->node.a_flags);
60         /*
61          * If the work is already pending, no need to raise the IPI.
62          * The pairing smp_mb() in irq_work_single() makes sure
63          * everything we did before is visible.
64          */
65         if (oflags & IRQ_WORK_PENDING)
66                 return false;
67         return true;
68 }
69
70 void __weak arch_irq_work_raise(void)
71 {
72         /*
73          * Lame architectures will get the timer tick callback
74          */
75 }
76
77 /* Enqueue on current CPU, work must already be claimed and preempt disabled */
78 static void __irq_work_queue_local(struct irq_work *work)
79 {
80         struct llist_head *list;
81         bool rt_lazy_work = false;
82         bool lazy_work = false;
83         int work_flags;
84
85         work_flags = atomic_read(&work->node.a_flags);
86         if (work_flags & IRQ_WORK_LAZY)
87                 lazy_work = true;
88         else if (IS_ENABLED(CONFIG_PREEMPT_RT) &&
89                  !(work_flags & IRQ_WORK_HARD_IRQ))
90                 rt_lazy_work = true;
91
92         if (lazy_work || rt_lazy_work)
93                 list = this_cpu_ptr(&lazy_list);
94         else
95                 list = this_cpu_ptr(&raised_list);
96
97         if (!llist_add(&work->node.llist, list))
98                 return;
99
100         /* If the work is "lazy", handle it from next tick if any */
101         if (!lazy_work || tick_nohz_tick_stopped())
102                 arch_irq_work_raise();
103 }
104
105 /* Enqueue the irq work @work on the current CPU */
106 bool irq_work_queue(struct irq_work *work)
107 {
108         /* Only queue if not already pending */
109         if (!irq_work_claim(work))
110                 return false;
111
112         /* Queue the entry and raise the IPI if needed. */
113         preempt_disable();
114         __irq_work_queue_local(work);
115         preempt_enable();
116
117         return true;
118 }
119 EXPORT_SYMBOL_GPL(irq_work_queue);
120
121 /*
122  * Enqueue the irq_work @work on @cpu unless it's already pending
123  * somewhere.
124  *
125  * Can be re-enqueued while the callback is still in progress.
126  */
127 bool irq_work_queue_on(struct irq_work *work, int cpu)
128 {
129 #ifndef CONFIG_SMP
130         return irq_work_queue(work);
131
132 #else /* CONFIG_SMP: */
133         /* All work should have been flushed before going offline */
134         WARN_ON_ONCE(cpu_is_offline(cpu));
135
136         /* Only queue if not already pending */
137         if (!irq_work_claim(work))
138                 return false;
139
140         kasan_record_aux_stack_noalloc(work);
141
142         preempt_disable();
143         if (cpu != smp_processor_id()) {
144                 /* Arch remote IPI send/receive backend aren't NMI safe */
145                 WARN_ON_ONCE(in_nmi());
146
147                 /*
148                  * On PREEMPT_RT the items which are not marked as
149                  * IRQ_WORK_HARD_IRQ are added to the lazy list and a HARD work
150                  * item is used on the remote CPU to wake the thread.
151                  */
152                 if (IS_ENABLED(CONFIG_PREEMPT_RT) &&
153                     !(atomic_read(&work->node.a_flags) & IRQ_WORK_HARD_IRQ)) {
154
155                         if (!llist_add(&work->node.llist, &per_cpu(lazy_list, cpu)))
156                                 goto out;
157
158                         work = &per_cpu(irq_work_wakeup, cpu);
159                         if (!irq_work_claim(work))
160                                 goto out;
161                 }
162
163                 __smp_call_single_queue(cpu, &work->node.llist);
164         } else {
165                 __irq_work_queue_local(work);
166         }
167 out:
168         preempt_enable();
169
170         return true;
171 #endif /* CONFIG_SMP */
172 }
173
174 bool irq_work_needs_cpu(void)
175 {
176         struct llist_head *raised, *lazy;
177
178         raised = this_cpu_ptr(&raised_list);
179         lazy = this_cpu_ptr(&lazy_list);
180
181         if (llist_empty(raised) || arch_irq_work_has_interrupt())
182                 if (llist_empty(lazy))
183                         return false;
184
185         /* All work should have been flushed before going offline */
186         WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
187
188         return true;
189 }
190
191 void irq_work_single(void *arg)
192 {
193         struct irq_work *work = arg;
194         int flags;
195
196         /*
197          * Clear the PENDING bit, after this point the @work can be re-used.
198          * The PENDING bit acts as a lock, and we own it, so we can clear it
199          * without atomic ops.
200          */
201         flags = atomic_read(&work->node.a_flags);
202         flags &= ~IRQ_WORK_PENDING;
203         atomic_set(&work->node.a_flags, flags);
204
205         /*
206          * See irq_work_claim().
207          */
208         smp_mb();
209
210         lockdep_irq_work_enter(flags);
211         work->func(work);
212         lockdep_irq_work_exit(flags);
213
214         /*
215          * Clear the BUSY bit, if set, and return to the free state if no-one
216          * else claimed it meanwhile.
217          */
218         (void)atomic_cmpxchg(&work->node.a_flags, flags, flags & ~IRQ_WORK_BUSY);
219
220         if ((IS_ENABLED(CONFIG_PREEMPT_RT) && !irq_work_is_hard(work)) ||
221             !arch_irq_work_has_interrupt())
222                 rcuwait_wake_up(&work->irqwait);
223 }
224
225 static void irq_work_run_list(struct llist_head *list)
226 {
227         struct irq_work *work, *tmp;
228         struct llist_node *llnode;
229
230         /*
231          * On PREEMPT_RT IRQ-work which is not marked as HARD will be processed
232          * in a per-CPU thread in preemptible context. Only the items which are
233          * marked as IRQ_WORK_HARD_IRQ will be processed in hardirq context.
234          */
235         BUG_ON(!irqs_disabled() && !IS_ENABLED(CONFIG_PREEMPT_RT));
236
237         if (llist_empty(list))
238                 return;
239
240         llnode = llist_del_all(list);
241         llist_for_each_entry_safe(work, tmp, llnode, node.llist)
242                 irq_work_single(work);
243 }
244
245 /*
246  * hotplug calls this through:
247  *  hotplug_cfd() -> flush_smp_call_function_queue()
248  */
249 void irq_work_run(void)
250 {
251         irq_work_run_list(this_cpu_ptr(&raised_list));
252         if (!IS_ENABLED(CONFIG_PREEMPT_RT))
253                 irq_work_run_list(this_cpu_ptr(&lazy_list));
254         else
255                 wake_irq_workd();
256 }
257 EXPORT_SYMBOL_GPL(irq_work_run);
258
259 void irq_work_tick(void)
260 {
261         struct llist_head *raised = this_cpu_ptr(&raised_list);
262
263         if (!llist_empty(raised) && !arch_irq_work_has_interrupt())
264                 irq_work_run_list(raised);
265
266         if (!IS_ENABLED(CONFIG_PREEMPT_RT))
267                 irq_work_run_list(this_cpu_ptr(&lazy_list));
268         else
269                 wake_irq_workd();
270 }
271
272 /*
273  * Synchronize against the irq_work @entry, ensures the entry is not
274  * currently in use.
275  */
276 void irq_work_sync(struct irq_work *work)
277 {
278         lockdep_assert_irqs_enabled();
279         might_sleep();
280
281         if ((IS_ENABLED(CONFIG_PREEMPT_RT) && !irq_work_is_hard(work)) ||
282             !arch_irq_work_has_interrupt()) {
283                 rcuwait_wait_event(&work->irqwait, !irq_work_is_busy(work),
284                                    TASK_UNINTERRUPTIBLE);
285                 return;
286         }
287
288         while (irq_work_is_busy(work))
289                 cpu_relax();
290 }
291 EXPORT_SYMBOL_GPL(irq_work_sync);
292
293 static void run_irq_workd(unsigned int cpu)
294 {
295         irq_work_run_list(this_cpu_ptr(&lazy_list));
296 }
297
298 static void irq_workd_setup(unsigned int cpu)
299 {
300         sched_set_fifo_low(current);
301 }
302
303 static struct smp_hotplug_thread irqwork_threads = {
304         .store                  = &irq_workd,
305         .setup                  = irq_workd_setup,
306         .thread_should_run      = irq_workd_should_run,
307         .thread_fn              = run_irq_workd,
308         .thread_comm            = "irq_work/%u",
309 };
310
311 static __init int irq_work_init_threads(void)
312 {
313         if (IS_ENABLED(CONFIG_PREEMPT_RT))
314                 BUG_ON(smpboot_register_percpu_thread(&irqwork_threads));
315         return 0;
316 }
317 early_initcall(irq_work_init_threads);