LXR linux/arch/powerpc/kernel/eeh

   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
  37static DEFINE_SPINLOCK(eeh_eventlist_lock);
  38static struct semaphore eeh_eventlist_sem;
  39LIST_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 */
  51static 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 */
 102int 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 */
 129int 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 */
 162void 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