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 */ 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#%x\n", 79 pe->phb->global_number); 80 else 81 pr_info("EEH: Detected PCI bus error on " 82 "PHB#%x-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 */ 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 */ 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 */ 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