1 /*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License as published by
4 * the Free Software Foundation; either version 2 of the License, or
5 * (at your option) any later version.
6 *
7 * This program is distributed in the hope that it will be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 * GNU General Public License for more details.
11 *
12 * You should have received a copy of the GNU General Public License
13 * along with this program; if not, write to the Free Software
14 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
15 *
16 * Copyright (c) 2005 Linas Vepstas <linas@linas.org>
17 */
18
19 #include <linux/delay.h>
20 #include <linux/list.h>
21 #include <linux/sched.h>
22 #include <linux/semaphore.h>
23 #include <linux/pci.h>
24 #include <linux/slab.h>
25 #include <linux/kthread.h>
26 #include <asm/eeh_event.h>
27 #include <asm/ppc-pci.h>
28
29 /** Overview:
30 * EEH error states may be detected within exception handlers;
31 * however, the recovery processing needs to occur asynchronously
32 * in a normal kernel context and not an interrupt context.
33 * This pair of routines creates an event and queues it onto a
34 * work-queue, where a worker thread can drive recovery.
35 */
36
37 static DEFINE_SPINLOCK(eeh_eventlist_lock);
38 static struct semaphore eeh_eventlist_sem;
39 static LIST_HEAD(eeh_eventlist);
40
41 /**
42 * eeh_event_handler - Dispatch EEH events.
43 * @dummy - unused
44 *
45 * The detection of a frozen slot can occur inside an interrupt,
46 * where it can be hard to do anything about it. The goal of this
47 * routine is to pull these detection events out of the context
48 * of the interrupt handler, and re-dispatch them for processing
49 * at a later time in a normal context.
50 */
eeh_event_handler(void * dummy)51 static int eeh_event_handler(void * dummy)
52 {
53 unsigned long flags;
54 struct eeh_event *event;
55 struct eeh_pe *pe;
56
57 while (!kthread_should_stop()) {
58 if (down_interruptible(&eeh_eventlist_sem))
59 break;
60
61 /* Fetch EEH event from the queue */
62 spin_lock_irqsave(&eeh_eventlist_lock, flags);
63 event = NULL;
64 if (!list_empty(&eeh_eventlist)) {
65 event = list_entry(eeh_eventlist.next,
66 struct eeh_event, list);
67 list_del(&event->list);
68 }
69 spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
70 if (!event)
71 continue;
72
73 /* We might have event without binding PE */
74 pe = event->pe;
75 if (pe) {
76 if (pe->type & EEH_PE_PHB)
77 pr_info("EEH: Detected error on PHB#%x\n",
78 pe->phb->global_number);
79 else
80 pr_info("EEH: Detected PCI bus error on "
81 "PHB#%x-PE#%x\n",
82 pe->phb->global_number, pe->addr);
83 eeh_handle_normal_event(pe);
84 } else {
85 eeh_handle_special_event();
86 }
87
88 kfree(event);
89 }
90
91 return 0;
92 }
93
94 /**
95 * eeh_event_init - Start kernel thread to handle EEH events
96 *
97 * This routine is called to start the kernel thread for processing
98 * EEH event.
99 */
eeh_event_init(void)100 int eeh_event_init(void)
101 {
102 struct task_struct *t;
103 int ret = 0;
104
105 /* Initialize semaphore */
106 sema_init(&eeh_eventlist_sem, 0);
107
108 t = kthread_run(eeh_event_handler, NULL, "eehd");
109 if (IS_ERR(t)) {
110 ret = PTR_ERR(t);
111 pr_err("%s: Failed to start EEH daemon (%d)\n",
112 __func__, ret);
113 return ret;
114 }
115
116 return 0;
117 }
118
119 /**
120 * eeh_send_failure_event - Generate a PCI error event
121 * @pe: EEH PE
122 *
123 * This routine can be called within an interrupt context;
124 * the actual event will be delivered in a normal context
125 * (from a workqueue).
126 */
eeh_send_failure_event(struct eeh_pe * pe)127 int eeh_send_failure_event(struct eeh_pe *pe)
128 {
129 unsigned long flags;
130 struct eeh_event *event;
131
132 event = kzalloc(sizeof(*event), GFP_ATOMIC);
133 if (!event) {
134 pr_err("EEH: out of memory, event not handled\n");
135 return -ENOMEM;
136 }
137 event->pe = pe;
138
139 /* We may or may not be called in an interrupt context */
140 spin_lock_irqsave(&eeh_eventlist_lock, flags);
141 list_add(&event->list, &eeh_eventlist);
142 spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
143
144 /* For EEH deamon to knick in */
145 up(&eeh_eventlist_sem);
146
147 return 0;
148 }
149
150 /**
151 * eeh_remove_event - Remove EEH event from the queue
152 * @pe: Event binding to the PE
153 * @force: Event will be removed unconditionally
154 *
155 * On PowerNV platform, we might have subsequent coming events
156 * is part of the former one. For that case, those subsequent
157 * coming events are totally duplicated and unnecessary, thus
158 * they should be removed.
159 */
eeh_remove_event(struct eeh_pe * pe,bool force)160 void eeh_remove_event(struct eeh_pe *pe, bool force)
161 {
162 unsigned long flags;
163 struct eeh_event *event, *tmp;
164
165 /*
166 * If we have NULL PE passed in, we have dead IOC
167 * or we're sure we can report all existing errors
168 * by the caller.
169 *
170 * With "force", the event with associated PE that
171 * have been isolated, the event won't be removed
172 * to avoid event lost.
173 */
174 spin_lock_irqsave(&eeh_eventlist_lock, flags);
175 list_for_each_entry_safe(event, tmp, &eeh_eventlist, list) {
176 if (!force && event->pe &&
177 (event->pe->state & EEH_PE_ISOLATED))
178 continue;
179
180 if (!pe) {
181 list_del(&event->list);
182 kfree(event);
183 } else if (pe->type & EEH_PE_PHB) {
184 if (event->pe && event->pe->phb == pe->phb) {
185 list_del(&event->list);
186 kfree(event);
187 }
188 } else if (event->pe == pe) {
189 list_del(&event->list);
190 kfree(event);
191 }
192 }
193 spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
194 }
195
