1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *
4 * Copyright (c) 2005 Linas Vepstas <linas@linas.org>
5 */
6
7#include <linux/delay.h>
8#include <linux/list.h>
9#include <linux/sched.h>
10#include <linux/semaphore.h>
11#include <linux/pci.h>
12#include <linux/slab.h>
13#include <linux/kthread.h>
14#include <asm/eeh_event.h>
15#include <asm/ppc-pci.h>
16
17/** Overview:
18 *  EEH error states may be detected within exception handlers;
19 *  however, the recovery processing needs to occur asynchronously
20 *  in a normal kernel context and not an interrupt context.
21 *  This pair of routines creates an event and queues it onto a
22 *  work-queue, where a worker thread can drive recovery.
23 */
24
25static DEFINE_SPINLOCK(eeh_eventlist_lock);
26static DECLARE_COMPLETION(eeh_eventlist_event);
27static LIST_HEAD(eeh_eventlist);
28
29/**
30 * eeh_event_handler - Dispatch EEH events.
31 * @dummy - unused
32 *
33 * The detection of a frozen slot can occur inside an interrupt,
34 * where it can be hard to do anything about it.  The goal of this
35 * routine is to pull these detection events out of the context
36 * of the interrupt handler, and re-dispatch them for processing
37 * at a later time in a normal context.
38 */
39static int eeh_event_handler(void * dummy)
40{
41	unsigned long flags;
42	struct eeh_event *event;
43
44	while (!kthread_should_stop()) {
45		if (wait_for_completion_interruptible(&eeh_eventlist_event))
46			break;
47
48		/* Fetch EEH event from the queue */
49		spin_lock_irqsave(&eeh_eventlist_lock, flags);
50		event = NULL;
51		if (!list_empty(&eeh_eventlist)) {
52			event = list_entry(eeh_eventlist.next,
53					   struct eeh_event, list);
54			list_del(&event->list);
55		}
56		spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
57		if (!event)
58			continue;
59
60		/* We might have event without binding PE */
61		if (event->pe)
62			eeh_handle_normal_event(event->pe);
63		else
64			eeh_handle_special_event();
65
66		kfree(event);
67	}
68
69	return 0;
70}
71
72/**
73 * eeh_event_init - Start kernel thread to handle EEH events
74 *
75 * This routine is called to start the kernel thread for processing
76 * EEH event.
77 */
78int eeh_event_init(void)
79{
80	struct task_struct *t;
81	int ret = 0;
82
83	t = kthread_run(eeh_event_handler, NULL, "eehd");
84	if (IS_ERR(t)) {
85		ret = PTR_ERR(t);
86		pr_err("%s: Failed to start EEH daemon (%d)\n",
87			__func__, ret);
88		return ret;
89	}
90
91	return 0;
92}
93
94/**
95 * eeh_send_failure_event - Generate a PCI error event
96 * @pe: EEH PE
97 *
98 * This routine can be called within an interrupt context;
99 * the actual event will be delivered in a normal context
100 * (from a workqueue).
101 */
102int __eeh_send_failure_event(struct eeh_pe *pe)
103{
104	unsigned long flags;
105	struct eeh_event *event;
106
107	event = kzalloc(sizeof(*event), GFP_ATOMIC);
108	if (!event) {
109		pr_err("EEH: out of memory, event not handled\n");
110		return -ENOMEM;
111	}
112	event->pe = pe;
113
114	/*
115	 * Mark the PE as recovering before inserting it in the queue.
116	 * This prevents the PE from being free()ed by a hotplug driver
117	 * while the PE is sitting in the event queue.
118	 */
119	if (pe) {
120#ifdef CONFIG_STACKTRACE
121		/*
122		 * Save the current stack trace so we can dump it from the
123		 * event handler thread.
124		 */
125		pe->trace_entries = stack_trace_save(pe->stack_trace,
126					 ARRAY_SIZE(pe->stack_trace), 0);
127#endif /* CONFIG_STACKTRACE */
128
129		eeh_pe_state_mark(pe, EEH_PE_RECOVERING);
130	}
131
132	/* We may or may not be called in an interrupt context */
133	spin_lock_irqsave(&eeh_eventlist_lock, flags);
134	list_add(&event->list, &eeh_eventlist);
135	spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
136
137	/* For EEH deamon to knick in */
138	complete(&eeh_eventlist_event);
139
140	return 0;
141}
142
143int eeh_send_failure_event(struct eeh_pe *pe)
144{
145	/*
146	 * If we've manually suppressed recovery events via debugfs
147	 * then just drop it on the floor.
148	 */
149	if (eeh_debugfs_no_recover) {
150		pr_err("EEH: Event dropped due to no_recover setting\n");
151		return 0;
152	}
153
154	return __eeh_send_failure_event(pe);
155}
156
157/**
158 * eeh_remove_event - Remove EEH event from the queue
159 * @pe: Event binding to the PE
160 * @force: Event will be removed unconditionally
161 *
162 * On PowerNV platform, we might have subsequent coming events
163 * is part of the former one. For that case, those subsequent
164 * coming events are totally duplicated and unnecessary, thus
165 * they should be removed.
166 */
167void eeh_remove_event(struct eeh_pe *pe, bool force)
168{
169	unsigned long flags;
170	struct eeh_event *event, *tmp;
171
172	/*
173	 * If we have NULL PE passed in, we have dead IOC
174	 * or we're sure we can report all existing errors
175	 * by the caller.
176	 *
177	 * With "force", the event with associated PE that
178	 * have been isolated, the event won't be removed
179	 * to avoid event lost.
180	 */
181	spin_lock_irqsave(&eeh_eventlist_lock, flags);
182	list_for_each_entry_safe(event, tmp, &eeh_eventlist, list) {
183		if (!force && event->pe &&
184		    (event->pe->state & EEH_PE_ISOLATED))
185			continue;
186
187		if (!pe) {
188			list_del(&event->list);
189			kfree(event);
190		} else if (pe->type & EEH_PE_PHB) {
191			if (event->pe && event->pe->phb == pe->phb) {
192				list_del(&event->list);
193				kfree(event);
194			}
195		} else if (event->pe == pe) {
196			list_del(&event->list);
197			kfree(event);
198		}
199	}
200	spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
201}
202