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eeh_event.c

/*
 * eeh_event.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 * Copyright (c) 2005 Linas Vepstas <linas@linas.org>
 */

#include <linux/delay.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/workqueue.h>
#include <asm/eeh_event.h>
#include <asm/ppc-pci.h>

/** Overview:
 *  EEH error states may be detected within exception handlers;
 *  however, the recovery processing needs to occur asynchronously
 *  in a normal kernel context and not an interrupt context.
 *  This pair of routines creates an event and queues it onto a
 *  work-queue, where a worker thread can drive recovery.
 */

/* EEH event workqueue setup. */
static DEFINE_SPINLOCK(eeh_eventlist_lock);
LIST_HEAD(eeh_eventlist);
static void eeh_thread_launcher(struct work_struct *);
DECLARE_WORK(eeh_event_wq, eeh_thread_launcher);

/* Serialize reset sequences for a given pci device */
DEFINE_MUTEX(eeh_event_mutex);

/**
 * eeh_event_handler - dispatch EEH events.
 * @dummy - unused
 *
 * The detection of a frozen slot can occur inside an interrupt,
 * where it can be hard to do anything about it.  The goal of this
 * routine is to pull these detection events out of the context
 * of the interrupt handler, and re-dispatch them for processing
 * at a later time in a normal context.
 */
static int eeh_event_handler(void * dummy)
{
      unsigned long flags;
      struct eeh_event  *event;
      struct pci_dn *pdn;

      daemonize ("eehd");
      set_current_state(TASK_INTERRUPTIBLE);

      spin_lock_irqsave(&eeh_eventlist_lock, flags);
      event = NULL;

      /* Unqueue the event, get ready to process. */
      if (!list_empty(&eeh_eventlist)) {
            event = list_entry(eeh_eventlist.next, struct eeh_event, list);
            list_del(&event->list);
      }
      spin_unlock_irqrestore(&eeh_eventlist_lock, flags);

      if (event == NULL)
            return 0;

      /* Serialize processing of EEH events */
      mutex_lock(&eeh_event_mutex);
      eeh_mark_slot(event->dn, EEH_MODE_RECOVERING);

      printk(KERN_INFO "EEH: Detected PCI bus error on device %s\n",
             pci_name(event->dev));

      pdn = handle_eeh_events(event);

      eeh_clear_slot(event->dn, EEH_MODE_RECOVERING);
      pci_dev_put(event->dev);
      kfree(event);
      mutex_unlock(&eeh_event_mutex);

      /* If there are no new errors after an hour, clear the counter. */
      if (pdn && pdn->eeh_freeze_count>0) {
            msleep_interruptible (3600*1000);
            if (pdn->eeh_freeze_count>0)
                  pdn->eeh_freeze_count--;
      }

      return 0;
}

/**
 * eeh_thread_launcher
 * @dummy - unused
 */
static void eeh_thread_launcher(struct work_struct *dummy)
{
      if (kernel_thread(eeh_event_handler, NULL, CLONE_KERNEL) < 0)
            printk(KERN_ERR "Failed to start EEH daemon\n");
}

/**
 * eeh_send_failure_event - generate a PCI error event
 * @dev pci device
 *
 * This routine can be called within an interrupt context;
 * the actual event will be delivered in a normal context
 * (from a workqueue).
 */
int eeh_send_failure_event (struct device_node *dn,
                            struct pci_dev *dev)
{
      unsigned long flags;
      struct eeh_event *event;
      const char *location;

      if (!mem_init_done) {
            printk(KERN_ERR "EEH: event during early boot not handled\n");
            location = of_get_property(dn, "ibm,loc-code", NULL);
            printk(KERN_ERR "EEH: device node = %s\n", dn->full_name);
            printk(KERN_ERR "EEH: PCI location = %s\n", location);
            return 1;
      }
      event = kmalloc(sizeof(*event), GFP_ATOMIC);
      if (event == NULL) {
            printk (KERN_ERR "EEH: out of memory, event not handled\n");
            return 1;
      }

      if (dev)
            pci_dev_get(dev);

      event->dn = dn;
      event->dev = dev;

      /* We may or may not be called in an interrupt context */
      spin_lock_irqsave(&eeh_eventlist_lock, flags);
      list_add(&event->list, &eeh_eventlist);
      spin_unlock_irqrestore(&eeh_eventlist_lock, flags);

      schedule_work(&eeh_event_wq);

      return 0;
}

/********************** END OF FILE ******************************/

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