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
25 static DEFINE_SPINLOCK(eeh_eventlist_lock);
26 static DECLARE_COMPLETION(eeh_eventlist_event);
27 static 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 */
39 static 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 */
78 int 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 */
102 int __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
143 int eeh_send_failure_event(struct eeh_pe *pe)
144 {
145 /*
146 * If we've manually supressed 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 */
167 void 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 }