xref: /openbmc/linux/kernel/irq/spurious.c (revision b34e08d5)
1 /*
2  * linux/kernel/irq/spurious.c
3  *
4  * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
5  *
6  * This file contains spurious interrupt handling.
7  */
8 
9 #include <linux/jiffies.h>
10 #include <linux/irq.h>
11 #include <linux/module.h>
12 #include <linux/kallsyms.h>
13 #include <linux/interrupt.h>
14 #include <linux/moduleparam.h>
15 #include <linux/timer.h>
16 
17 #include "internals.h"
18 
19 static int irqfixup __read_mostly;
20 
21 #define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)
22 static void poll_spurious_irqs(unsigned long dummy);
23 static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs, 0, 0);
24 static int irq_poll_cpu;
25 static atomic_t irq_poll_active;
26 
27 /*
28  * We wait here for a poller to finish.
29  *
30  * If the poll runs on this CPU, then we yell loudly and return
31  * false. That will leave the interrupt line disabled in the worst
32  * case, but it should never happen.
33  *
34  * We wait until the poller is done and then recheck disabled and
35  * action (about to be disabled). Only if it's still active, we return
36  * true and let the handler run.
37  */
38 bool irq_wait_for_poll(struct irq_desc *desc)
39 {
40 	if (WARN_ONCE(irq_poll_cpu == smp_processor_id(),
41 		      "irq poll in progress on cpu %d for irq %d\n",
42 		      smp_processor_id(), desc->irq_data.irq))
43 		return false;
44 
45 #ifdef CONFIG_SMP
46 	do {
47 		raw_spin_unlock(&desc->lock);
48 		while (irqd_irq_inprogress(&desc->irq_data))
49 			cpu_relax();
50 		raw_spin_lock(&desc->lock);
51 	} while (irqd_irq_inprogress(&desc->irq_data));
52 	/* Might have been disabled in meantime */
53 	return !irqd_irq_disabled(&desc->irq_data) && desc->action;
54 #else
55 	return false;
56 #endif
57 }
58 
59 
60 /*
61  * Recovery handler for misrouted interrupts.
62  */
63 static int try_one_irq(int irq, struct irq_desc *desc, bool force)
64 {
65 	irqreturn_t ret = IRQ_NONE;
66 	struct irqaction *action;
67 
68 	raw_spin_lock(&desc->lock);
69 
70 	/*
71 	 * PER_CPU, nested thread interrupts and interrupts explicitely
72 	 * marked polled are excluded from polling.
73 	 */
74 	if (irq_settings_is_per_cpu(desc) ||
75 	    irq_settings_is_nested_thread(desc) ||
76 	    irq_settings_is_polled(desc))
77 		goto out;
78 
79 	/*
80 	 * Do not poll disabled interrupts unless the spurious
81 	 * disabled poller asks explicitely.
82 	 */
83 	if (irqd_irq_disabled(&desc->irq_data) && !force)
84 		goto out;
85 
86 	/*
87 	 * All handlers must agree on IRQF_SHARED, so we test just the
88 	 * first.
89 	 */
90 	action = desc->action;
91 	if (!action || !(action->flags & IRQF_SHARED) ||
92 	    (action->flags & __IRQF_TIMER))
93 		goto out;
94 
95 	/* Already running on another processor */
96 	if (irqd_irq_inprogress(&desc->irq_data)) {
97 		/*
98 		 * Already running: If it is shared get the other
99 		 * CPU to go looking for our mystery interrupt too
100 		 */
101 		desc->istate |= IRQS_PENDING;
102 		goto out;
103 	}
104 
105 	/* Mark it poll in progress */
106 	desc->istate |= IRQS_POLL_INPROGRESS;
107 	do {
108 		if (handle_irq_event(desc) == IRQ_HANDLED)
109 			ret = IRQ_HANDLED;
110 		/* Make sure that there is still a valid action */
111 		action = desc->action;
112 	} while ((desc->istate & IRQS_PENDING) && action);
113 	desc->istate &= ~IRQS_POLL_INPROGRESS;
114 out:
115 	raw_spin_unlock(&desc->lock);
116 	return ret == IRQ_HANDLED;
117 }
118 
119 static int misrouted_irq(int irq)
120 {
121 	struct irq_desc *desc;
122 	int i, ok = 0;
123 
124 	if (atomic_inc_return(&irq_poll_active) != 1)
125 		goto out;
126 
127 	irq_poll_cpu = smp_processor_id();
128 
129 	for_each_irq_desc(i, desc) {
130 		if (!i)
131 			 continue;
132 
133 		if (i == irq)	/* Already tried */
134 			continue;
135 
136 		if (try_one_irq(i, desc, false))
137 			ok = 1;
138 	}
139 out:
140 	atomic_dec(&irq_poll_active);
141 	/* So the caller can adjust the irq error counts */
142 	return ok;
143 }
144 
145 static void poll_spurious_irqs(unsigned long dummy)
146 {
147 	struct irq_desc *desc;
148 	int i;
149 
150 	if (atomic_inc_return(&irq_poll_active) != 1)
151 		goto out;
152 	irq_poll_cpu = smp_processor_id();
153 
154 	for_each_irq_desc(i, desc) {
155 		unsigned int state;
156 
157 		if (!i)
158 			 continue;
159 
160 		/* Racy but it doesn't matter */
161 		state = desc->istate;
162 		barrier();
163 		if (!(state & IRQS_SPURIOUS_DISABLED))
164 			continue;
165 
166 		local_irq_disable();
167 		try_one_irq(i, desc, true);
168 		local_irq_enable();
169 	}
170 out:
171 	atomic_dec(&irq_poll_active);
172 	mod_timer(&poll_spurious_irq_timer,
173 		  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
174 }
175 
176 static inline int bad_action_ret(irqreturn_t action_ret)
177 {
178 	if (likely(action_ret <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
179 		return 0;
180 	return 1;
181 }
182 
183 /*
184  * If 99,900 of the previous 100,000 interrupts have not been handled
185  * then assume that the IRQ is stuck in some manner. Drop a diagnostic
186  * and try to turn the IRQ off.
187  *
188  * (The other 100-of-100,000 interrupts may have been a correctly
189  *  functioning device sharing an IRQ with the failing one)
190  */
191 static void
192 __report_bad_irq(unsigned int irq, struct irq_desc *desc,
193 		 irqreturn_t action_ret)
194 {
195 	struct irqaction *action;
196 	unsigned long flags;
197 
198 	if (bad_action_ret(action_ret)) {
199 		printk(KERN_ERR "irq event %d: bogus return value %x\n",
200 				irq, action_ret);
201 	} else {
202 		printk(KERN_ERR "irq %d: nobody cared (try booting with "
203 				"the \"irqpoll\" option)\n", irq);
204 	}
205 	dump_stack();
206 	printk(KERN_ERR "handlers:\n");
207 
208 	/*
209 	 * We need to take desc->lock here. note_interrupt() is called
210 	 * w/o desc->lock held, but IRQ_PROGRESS set. We might race
211 	 * with something else removing an action. It's ok to take
212 	 * desc->lock here. See synchronize_irq().
213 	 */
214 	raw_spin_lock_irqsave(&desc->lock, flags);
215 	action = desc->action;
216 	while (action) {
217 		printk(KERN_ERR "[<%p>] %pf", action->handler, action->handler);
218 		if (action->thread_fn)
219 			printk(KERN_CONT " threaded [<%p>] %pf",
220 					action->thread_fn, action->thread_fn);
221 		printk(KERN_CONT "\n");
222 		action = action->next;
223 	}
224 	raw_spin_unlock_irqrestore(&desc->lock, flags);
225 }
226 
227 static void
228 report_bad_irq(unsigned int irq, struct irq_desc *desc, irqreturn_t action_ret)
229 {
230 	static int count = 100;
231 
232 	if (count > 0) {
233 		count--;
234 		__report_bad_irq(irq, desc, action_ret);
235 	}
236 }
237 
238 static inline int
239 try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
240 		  irqreturn_t action_ret)
241 {
242 	struct irqaction *action;
243 
244 	if (!irqfixup)
245 		return 0;
246 
247 	/* We didn't actually handle the IRQ - see if it was misrouted? */
248 	if (action_ret == IRQ_NONE)
249 		return 1;
250 
251 	/*
252 	 * But for 'irqfixup == 2' we also do it for handled interrupts if
253 	 * they are marked as IRQF_IRQPOLL (or for irq zero, which is the
254 	 * traditional PC timer interrupt.. Legacy)
255 	 */
256 	if (irqfixup < 2)
257 		return 0;
258 
259 	if (!irq)
260 		return 1;
261 
262 	/*
263 	 * Since we don't get the descriptor lock, "action" can
264 	 * change under us.  We don't really care, but we don't
265 	 * want to follow a NULL pointer. So tell the compiler to
266 	 * just load it once by using a barrier.
267 	 */
268 	action = desc->action;
269 	barrier();
270 	return action && (action->flags & IRQF_IRQPOLL);
271 }
272 
273 void note_interrupt(unsigned int irq, struct irq_desc *desc,
274 		    irqreturn_t action_ret)
275 {
276 	if (desc->istate & IRQS_POLL_INPROGRESS ||
277 	    irq_settings_is_polled(desc))
278 		return;
279 
280 	/* we get here again via the threaded handler */
281 	if (action_ret == IRQ_WAKE_THREAD)
282 		return;
283 
284 	if (bad_action_ret(action_ret)) {
285 		report_bad_irq(irq, desc, action_ret);
286 		return;
287 	}
288 
289 	if (unlikely(action_ret == IRQ_NONE)) {
290 		/*
291 		 * If we are seeing only the odd spurious IRQ caused by
292 		 * bus asynchronicity then don't eventually trigger an error,
293 		 * otherwise the counter becomes a doomsday timer for otherwise
294 		 * working systems
295 		 */
296 		if (time_after(jiffies, desc->last_unhandled + HZ/10))
297 			desc->irqs_unhandled = 1;
298 		else
299 			desc->irqs_unhandled++;
300 		desc->last_unhandled = jiffies;
301 	}
302 
303 	if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {
304 		int ok = misrouted_irq(irq);
305 		if (action_ret == IRQ_NONE)
306 			desc->irqs_unhandled -= ok;
307 	}
308 
309 	desc->irq_count++;
310 	if (likely(desc->irq_count < 100000))
311 		return;
312 
313 	desc->irq_count = 0;
314 	if (unlikely(desc->irqs_unhandled > 99900)) {
315 		/*
316 		 * The interrupt is stuck
317 		 */
318 		__report_bad_irq(irq, desc, action_ret);
319 		/*
320 		 * Now kill the IRQ
321 		 */
322 		printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
323 		desc->istate |= IRQS_SPURIOUS_DISABLED;
324 		desc->depth++;
325 		irq_disable(desc);
326 
327 		mod_timer(&poll_spurious_irq_timer,
328 			  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
329 	}
330 	desc->irqs_unhandled = 0;
331 }
332 
333 bool noirqdebug __read_mostly;
334 
335 int noirqdebug_setup(char *str)
336 {
337 	noirqdebug = 1;
338 	printk(KERN_INFO "IRQ lockup detection disabled\n");
339 
340 	return 1;
341 }
342 
343 __setup("noirqdebug", noirqdebug_setup);
344 module_param(noirqdebug, bool, 0644);
345 MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");
346 
347 static int __init irqfixup_setup(char *str)
348 {
349 	irqfixup = 1;
350 	printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
351 	printk(KERN_WARNING "This may impact system performance.\n");
352 
353 	return 1;
354 }
355 
356 __setup("irqfixup", irqfixup_setup);
357 module_param(irqfixup, int, 0644);
358 
359 static int __init irqpoll_setup(char *str)
360 {
361 	irqfixup = 2;
362 	printk(KERN_WARNING "Misrouted IRQ fixup and polling support "
363 				"enabled\n");
364 	printk(KERN_WARNING "This may significantly impact system "
365 				"performance\n");
366 	return 1;
367 }
368 
369 __setup("irqpoll", irqpoll_setup);
370