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 <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 /* EEH event workqueue setup. */
  38 static DEFINE_SPINLOCK(eeh_eventlist_lock);
  39 LIST_HEAD(eeh_eventlist);
  40 static void eeh_thread_launcher(struct work_struct *);
  41 DECLARE_WORK(eeh_event_wq, eeh_thread_launcher);
  42
  43 /* Serialize reset sequences for a given pci device */
  44 DEFINE_MUTEX(eeh_event_mutex);
  45
  46 /**
  47  * eeh_event_handler - Dispatch EEH events.
  48  * @dummy - unused
  49  *
  50  * The detection of a frozen slot can occur inside an interrupt,
  51  * where it can be hard to do anything about it.  The goal of this
  52  * routine is to pull these detection events out of the context
  53  * of the interrupt handler, and re-dispatch them for processing
  54  * at a later time in a normal context.
  55  */
  56 static int eeh_event_handler(void * dummy)
  57 {
  58         unsigned long flags;
  59         struct eeh_event *event;
  60         struct eeh_pe *pe;
  61
  62         set_task_comm(current, "eehd");
  63
  64         spin_lock_irqsave(&eeh_eventlist_lock, flags);
  65         event = NULL;
  66
  67         /* Unqueue the event, get ready to process. */
  68         if (!list_empty(&eeh_eventlist)) {
  69                 event = list_entry(eeh_eventlist.next, struct eeh_event, list);
  70                 list_del(&event->list);
  71         }
  72         spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
  73
  74         if (event == NULL)
  75                 return 0;
  76
  77         /* Serialize processing of EEH events */
  78         mutex_lock(&eeh_event_mutex);
  79         pe = event->pe;
  80         eeh_pe_state_mark(pe, EEH_PE_RECOVERING);
  81         pr_info("EEH: Detected PCI bus error on PHB#%d-PE#%x\n",
  82                 pe->phb->global_number, pe->addr);
  83
  84         set_current_state(TASK_INTERRUPTIBLE);  /* Don't add to load average */
  85         eeh_handle_event(pe);
  86         eeh_pe_state_clear(pe, EEH_PE_RECOVERING);
  87
  88         kfree(event);
  89         mutex_unlock(&eeh_event_mutex);
  90
  91         /* If there are no new errors after an hour, clear the counter. */
  92         if (pe && pe->freeze_count > 0) {
  93                 msleep_interruptible(3600*1000);
  94                 if (pe->freeze_count > 0)
  95                         pe->freeze_count--;
  96
  97         }
  98
  99         return 0;
 100 }
 101
 102 /**
 103  * eeh_thread_launcher - Start kernel thread to handle EEH events
 104  * @dummy - unused
 105  *
 106  * This routine is called to start the kernel thread for processing
 107  * EEH event.
 108  */
 109 static void eeh_thread_launcher(struct work_struct *dummy)
 110 {
 111         if (kernel_thread(eeh_event_handler, NULL, CLONE_KERNEL) < 0)
 112                 printk(KERN_ERR "Failed to start EEH daemon\n");
 113 }
 114
 115 /**
 116  * eeh_send_failure_event - Generate a PCI error event
 117  * @pe: EEH PE
 118  *
 119  * This routine can be called within an interrupt context;
 120  * the actual event will be delivered in a normal context
 121  * (from a workqueue).
 122  */
 123 int eeh_send_failure_event(struct eeh_pe *pe)
 124 {
 125         unsigned long flags;
 126         struct eeh_event *event;
 127
 128         event = kzalloc(sizeof(*event), GFP_ATOMIC);
 129         if (!event) {
 130                 pr_err("EEH: out of memory, event not handled\n");
 131                 return -ENOMEM;
 132         }
 133         event->pe = pe;
 134
 135         /* We may or may not be called in an interrupt context */
 136         spin_lock_irqsave(&eeh_eventlist_lock, flags);
 137         list_add(&event->list, &eeh_eventlist);
 138         spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
 139
 140         schedule_work(&eeh_event_wq);
 141
 142         return 0;
 143 }