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