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// SPDX-License-Identifier: GPL-2.0-or-later
/*
*
* Copyright (c) 2005 Linas Vepstas <linas@linas.org>
*/
#include <linux/delay.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/semaphore.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/kthread.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.
*/
static DEFINE_SPINLOCK(eeh_eventlist_lock);
static DECLARE_COMPLETION(eeh_eventlist_event);
static LIST_HEAD(eeh_eventlist);
/**
* 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;
while (!kthread_should_stop()) {
if (wait_for_completion_interruptible(&eeh_eventlist_event))
break;
/* Fetch EEH event from the queue */
spin_lock_irqsave(&eeh_eventlist_lock, flags);
event = NULL;
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)
continue;
/* We might have event without binding PE */
if (event->pe)
eeh_handle_normal_event(event->pe);
else
eeh_handle_special_event();
kfree(event);
}
return 0;
}
/**
* eeh_event_init - Start kernel thread to handle EEH events
*
* This routine is called to start the kernel thread for processing
* EEH event.
*/
int eeh_event_init(void)
{
struct task_struct *t;
int ret = 0;
t = kthread_run(eeh_event_handler, NULL, "eehd");
if (IS_ERR(t)) {
ret = PTR_ERR(t);
pr_err("%s: Failed to start EEH daemon (%d)\n",
__func__, ret);
return ret;
}
return 0;
}
/**
* eeh_send_failure_event - Generate a PCI error event
* @pe: EEH PE
*
* 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 eeh_pe *pe)
{
unsigned long flags;
struct eeh_event *event;
event = kzalloc(sizeof(*event), GFP_ATOMIC);
if (!event) {
pr_err("EEH: out of memory, event not handled\n");
return -ENOMEM;
}
event->pe = pe;
/*
* Mark the PE as recovering before inserting it in the queue.
* This prevents the PE from being free()ed by a hotplug driver
* while the PE is sitting in the event queue.
*/
if (pe) {
#ifdef CONFIG_STACKTRACE
/*
* Save the current stack trace so we can dump it from the
* event handler thread.
*/
pe->trace_entries = stack_trace_save(pe->stack_trace,
ARRAY_SIZE(pe->stack_trace), 0);
#endif /* CONFIG_STACKTRACE */
eeh_pe_state_mark(pe, EEH_PE_RECOVERING);
}
/* 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);
/* For EEH deamon to knick in */
complete(&eeh_eventlist_event);
return 0;
}
int eeh_send_failure_event(struct eeh_pe *pe)
{
/*
* If we've manually suppressed recovery events via debugfs
* then just drop it on the floor.
*/
if (eeh_debugfs_no_recover) {
pr_err("EEH: Event dropped due to no_recover setting\n");
return 0;
}
return __eeh_send_failure_event(pe);
}
/**
* eeh_remove_event - Remove EEH event from the queue
* @pe: Event binding to the PE
* @force: Event will be removed unconditionally
*
* On PowerNV platform, we might have subsequent coming events
* is part of the former one. For that case, those subsequent
* coming events are totally duplicated and unnecessary, thus
* they should be removed.
*/
void eeh_remove_event(struct eeh_pe *pe, bool force)
{
unsigned long flags;
struct eeh_event *event, *tmp;
/*
* If we have NULL PE passed in, we have dead IOC
* or we're sure we can report all existing errors
* by the caller.
*
* With "force", the event with associated PE that
* have been isolated, the event won't be removed
* to avoid event lost.
*/
spin_lock_irqsave(&eeh_eventlist_lock, flags);
list_for_each_entry_safe(event, tmp, &eeh_eventlist, list) {
if (!force && event->pe &&
(event->pe->state & EEH_PE_ISOLATED))
continue;
if (!pe) {
list_del(&event->list);
kfree(event);
} else if (pe->type & EEH_PE_PHB) {
if (event->pe && event->pe->phb == pe->phb) {
list_del(&event->list);
kfree(event);
}
} else if (event->pe == pe) {
list_del(&event->list);
kfree(event);
}
}
spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
}
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