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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 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 			eeh_pe_state_mark(pe, EEH_PE_RECOVERING);
77 			if (pe->type & EEH_PE_PHB)
78 				pr_info("EEH: Detected error on PHB#%d\n",
79 					 pe->phb->global_number);
80 			else
81 				pr_info("EEH: Detected PCI bus error on "
82 					"PHB#%d-PE#%x\n",
83 					pe->phb->global_number, pe->addr);
84 			eeh_handle_event(pe);
85 			eeh_pe_state_clear(pe, EEH_PE_RECOVERING);
86 		} else {
87 			eeh_handle_event(NULL);
88 		}
89 
90 		kfree(event);
91 	}
92 
93 	return 0;
94 }
95 
96 /**
97  * eeh_event_init - Start kernel thread to handle EEH events
98  *
99  * This routine is called to start the kernel thread for processing
100  * EEH event.
101  */
eeh_event_init(void)102 int eeh_event_init(void)
103 {
104 	struct task_struct *t;
105 	int ret = 0;
106 
107 	/* Initialize semaphore */
108 	sema_init(&eeh_eventlist_sem, 0);
109 
110 	t = kthread_run(eeh_event_handler, NULL, "eehd");
111 	if (IS_ERR(t)) {
112 		ret = PTR_ERR(t);
113 		pr_err("%s: Failed to start EEH daemon (%d)\n",
114 			__func__, ret);
115 		return ret;
116 	}
117 
118 	return 0;
119 }
120 
121 /**
122  * eeh_send_failure_event - Generate a PCI error event
123  * @pe: EEH PE
124  *
125  * This routine can be called within an interrupt context;
126  * the actual event will be delivered in a normal context
127  * (from a workqueue).
128  */
eeh_send_failure_event(struct eeh_pe * pe)129 int eeh_send_failure_event(struct eeh_pe *pe)
130 {
131 	unsigned long flags;
132 	struct eeh_event *event;
133 
134 	event = kzalloc(sizeof(*event), GFP_ATOMIC);
135 	if (!event) {
136 		pr_err("EEH: out of memory, event not handled\n");
137 		return -ENOMEM;
138 	}
139 	event->pe = pe;
140 
141 	/* We may or may not be called in an interrupt context */
142 	spin_lock_irqsave(&eeh_eventlist_lock, flags);
143 	list_add(&event->list, &eeh_eventlist);
144 	spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
145 
146 	/* For EEH deamon to knick in */
147 	up(&eeh_eventlist_sem);
148 
149 	return 0;
150 }
151 
152 /**
153  * eeh_remove_event - Remove EEH event from the queue
154  * @pe: Event binding to the PE
155  * @force: Event will be removed unconditionally
156  *
157  * On PowerNV platform, we might have subsequent coming events
158  * is part of the former one. For that case, those subsequent
159  * coming events are totally duplicated and unnecessary, thus
160  * they should be removed.
161  */
eeh_remove_event(struct eeh_pe * pe,bool force)162 void eeh_remove_event(struct eeh_pe *pe, bool force)
163 {
164 	unsigned long flags;
165 	struct eeh_event *event, *tmp;
166 
167 	/*
168 	 * If we have NULL PE passed in, we have dead IOC
169 	 * or we're sure we can report all existing errors
170 	 * by the caller.
171 	 *
172 	 * With "force", the event with associated PE that
173 	 * have been isolated, the event won't be removed
174 	 * to avoid event lost.
175 	 */
176 	spin_lock_irqsave(&eeh_eventlist_lock, flags);
177 	list_for_each_entry_safe(event, tmp, &eeh_eventlist, list) {
178 		if (!force && event->pe &&
179 		    (event->pe->state & EEH_PE_ISOLATED))
180 			continue;
181 
182 		if (!pe) {
183 			list_del(&event->list);
184 			kfree(event);
185 		} else if (pe->type & EEH_PE_PHB) {
186 			if (event->pe && event->pe->phb == pe->phb) {
187 				list_del(&event->list);
188 				kfree(event);
189 			}
190 		} else if (event->pe == pe) {
191 			list_del(&event->list);
192 			kfree(event);
193 		}
194 	}
195 	spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
196 }
197