arch/powerpc/platforms/pseries/eeh_event.c

   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/mutex.h>
  22 #include <linux/sched.h>
  23 #include <linux/pci.h>
  24 #include <linux/slab.h>
  25 #include <linux/workqueue.h>
  26 #include <linux/kthread.h>
  27 #include <asm/eeh_event.h>
  28 #include <asm/ppc-pci.h>
  29
  30 /** Overview:
  31  *  EEH error states may be detected within exception handlers;
  32  *  however, the recovery processing needs to occur asynchronously
  33  *  in a normal kernel context and not an interrupt context.
  34  *  This pair of routines creates an event and queues it onto a
  35  *  work-queue, where a worker thread can drive recovery.
  36  */
  37
  38 /* EEH event workqueue setup. */
  39 static DEFINE_SPINLOCK(eeh_eventlist_lock);
  40 LIST_HEAD(eeh_eventlist);
  41 static void eeh_thread_launcher(struct work_struct *);
  42 DECLARE_WORK(eeh_event_wq, eeh_thread_launcher);
  43
  44 /* Serialize reset sequences for a given pci device */
  45 DEFINE_MUTEX(eeh_event_mutex);
  46
  47 /**
  48  * eeh_event_handler - Dispatch EEH events.
  49  * @dummy - unused
  50  *
  51  * The detection of a frozen slot can occur inside an interrupt,
  52  * where it can be hard to do anything about it.  The goal of this
  53  * routine is to pull these detection events out of the context
  54  * of the interrupt handler, and re-dispatch them for processing
  55  * at a later time in a normal context.
  56  */
  57 static int eeh_event_handler(void * dummy)
  58 {
  59         unsigned long flags;
  60         struct eeh_event *event;
  61         struct eeh_pe *pe;
  62
  63         spin_lock_irqsave(&eeh_eventlist_lock, flags);
  64         event = NULL;
  65
  66         /* Unqueue the event, get ready to process. */
  67         if (!list_empty(&eeh_eventlist)) {
  68                 event = list_entry(eeh_eventlist.next, struct eeh_event, list);
  69                 list_del(&event->list);
  70         }
  71         spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
  72
  73         if (event == NULL)
  74                 return 0;
  75
  76         /* Serialize processing of EEH events */
  77         mutex_lock(&eeh_event_mutex);
  78         pe = event->pe;
  79         eeh_pe_state_mark(pe, EEH_PE_RECOVERING);
  80         pr_info("EEH: Detected PCI bus error on PHB#%d-PE#%x\n",
  81                 pe->phb->global_number, pe->addr);
  82
  83         set_current_state(TASK_INTERRUPTIBLE);  /* Don't add to load average */
  84         eeh_handle_event(pe);
  85         eeh_pe_state_clear(pe, EEH_PE_RECOVERING);
  86
  87         kfree(event);
  88         mutex_unlock(&eeh_event_mutex);
  89
  90         /* If there are no new errors after an hour, clear the counter. */
  91         if (pe && pe->freeze_count > 0) {
  92                 msleep_interruptible(3600*1000);
  93                 if (pe->freeze_count > 0)
  94                         pe->freeze_count--;
  95
  96         }
  97
  98         return 0;
  99 }
 100
 101 /**
 102  * eeh_thread_launcher - Start kernel thread to handle EEH events
 103  * @dummy - unused
 104  *
 105  * This routine is called to start the kernel thread for processing
 106  * EEH event.
 107  */
 108 static void eeh_thread_launcher(struct work_struct *dummy)
 109 {
 110         if (IS_ERR(kthread_run(eeh_event_handler, NULL, "eehd")))
 111                 printk(KERN_ERR "Failed to start EEH daemon\n");
 112 }
 113
 114 /**
 115  * eeh_send_failure_event - Generate a PCI error event
 116  * @pe: EEH PE
 117  *
 118  * This routine can be called within an interrupt context;
 119  * the actual event will be delivered in a normal context
 120  * (from a workqueue).
 121  */
 122 int eeh_send_failure_event(struct eeh_pe *pe)
 123 {
 124         unsigned long flags;
 125         struct eeh_event *event;
 126
 127         event = kzalloc(sizeof(*event), GFP_ATOMIC);
 128         if (!event) {
 129                 pr_err("EEH: out of memory, event not handled\n");
 130                 return -ENOMEM;
 131         }
 132         event->pe = pe;
 133
 134         /* We may or may not be called in an interrupt context */
 135         spin_lock_irqsave(&eeh_eventlist_lock, flags);
 136         list_add(&event->list, &eeh_eventlist);
 137         spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
 138
 139         schedule_work(&eeh_event_wq);
 140
 141         return 0;
 142 }