Revision 8339f0008c47cdd921c73f6d53d5588b5484f93c authored by Eric W. Biederman on 29 January 2007, 20:19:05 UTC, committed by Linus Torvalds on 30 January 2007, 16:29:58 UTC
When the world was a simple and static place setting up irqs was easy. It sufficed to allocate a linux irq number and a find a free cpu vector we could receive that linux irq on. In those days it was a safe assumption that any allocated vector was actually in use so after one global pass through all of the vectors we would have none left. These days things are much more dynamic with interrupt controllers (in the form of MSI or MSI-X) appearing on plug in cards and linux irqs appearing and disappearing. As these irqs come and go vectors are allocated and freed, invalidating the ancient assumption that all allocated vectors stayed in use forever. So this patch modifies the vector allocator to walk through every possible vector before giving up, and to check to see if a vector is in use before assigning it. With these changes we stop leaking freed vectors and it becomes possible to allocate and free irq vectors all day long. This changed was modeled after the vector allocator on x86_64 where this limitation has already been removed. In essence we don't update the static variables that hold the position of the last vector we allocated until have successfully allocated another vector. This allows us to detect if we have completed one complete scan through all of the possible vectors. Acked-by: Auke Kok <auke-jan.h.kok@intel.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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rtmutex-debug.c
/*
* RT-Mutexes: blocking mutual exclusion locks with PI support
*
* started by Ingo Molnar and Thomas Gleixner:
*
* Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
* Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
*
* This code is based on the rt.c implementation in the preempt-rt tree.
* Portions of said code are
*
* Copyright (C) 2004 LynuxWorks, Inc., Igor Manyilov, Bill Huey
* Copyright (C) 2006 Esben Nielsen
* Copyright (C) 2006 Kihon Technologies Inc.,
* Steven Rostedt <rostedt@goodmis.org>
*
* See rt.c in preempt-rt for proper credits and further information
*/
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include <linux/syscalls.h>
#include <linux/interrupt.h>
#include <linux/plist.h>
#include <linux/fs.h>
#include <linux/debug_locks.h>
#include "rtmutex_common.h"
#ifdef CONFIG_DEBUG_RT_MUTEXES
# include "rtmutex-debug.h"
#else
# include "rtmutex.h"
#endif
# define TRACE_WARN_ON(x) WARN_ON(x)
# define TRACE_BUG_ON(x) BUG_ON(x)
# define TRACE_OFF() \
do { \
if (rt_trace_on) { \
rt_trace_on = 0; \
console_verbose(); \
if (spin_is_locked(¤t->pi_lock)) \
spin_unlock(¤t->pi_lock); \
} \
} while (0)
# define TRACE_OFF_NOLOCK() \
do { \
if (rt_trace_on) { \
rt_trace_on = 0; \
console_verbose(); \
} \
} while (0)
# define TRACE_BUG_LOCKED() \
do { \
TRACE_OFF(); \
BUG(); \
} while (0)
# define TRACE_WARN_ON_LOCKED(c) \
do { \
if (unlikely(c)) { \
TRACE_OFF(); \
WARN_ON(1); \
} \
} while (0)
# define TRACE_BUG_ON_LOCKED(c) \
do { \
if (unlikely(c)) \
TRACE_BUG_LOCKED(); \
} while (0)
#ifdef CONFIG_SMP
# define SMP_TRACE_BUG_ON_LOCKED(c) TRACE_BUG_ON_LOCKED(c)
#else
# define SMP_TRACE_BUG_ON_LOCKED(c) do { } while (0)
#endif
/*
* deadlock detection flag. We turn it off when we detect
* the first problem because we dont want to recurse back
* into the tracing code when doing error printk or
* executing a BUG():
*/
int rt_trace_on = 1;
void deadlock_trace_off(void)
{
rt_trace_on = 0;
}
static void printk_task(struct task_struct *p)
{
if (p)
printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
else
printk("<none>");
}
static void printk_lock(struct rt_mutex *lock, int print_owner)
{
if (lock->name)
printk(" [%p] {%s}\n",
lock, lock->name);
else
printk(" [%p] {%s:%d}\n",
lock, lock->file, lock->line);
if (print_owner && rt_mutex_owner(lock)) {
printk(".. ->owner: %p\n", lock->owner);
printk(".. held by: ");
printk_task(rt_mutex_owner(lock));
printk("\n");
}
}
void rt_mutex_debug_task_free(struct task_struct *task)
{
WARN_ON(!plist_head_empty(&task->pi_waiters));
WARN_ON(task->pi_blocked_on);
}
/*
* We fill out the fields in the waiter to store the information about
* the deadlock. We print when we return. act_waiter can be NULL in
* case of a remove waiter operation.
*/
void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
struct rt_mutex *lock)
{
struct task_struct *task;
if (!rt_trace_on || detect || !act_waiter)
return;
task = rt_mutex_owner(act_waiter->lock);
if (task && task != current) {
act_waiter->deadlock_task_pid = task->pid;
act_waiter->deadlock_lock = lock;
}
}
void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
{
struct task_struct *task;
if (!waiter->deadlock_lock || !rt_trace_on)
return;
task = find_task_by_pid(waiter->deadlock_task_pid);
if (!task)
return;
TRACE_OFF_NOLOCK();
printk("\n============================================\n");
printk( "[ BUG: circular locking deadlock detected! ]\n");
printk( "--------------------------------------------\n");
printk("%s/%d is deadlocking current task %s/%d\n\n",
task->comm, task->pid, current->comm, current->pid);
printk("\n1) %s/%d is trying to acquire this lock:\n",
current->comm, current->pid);
printk_lock(waiter->lock, 1);
printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);
printk_lock(waiter->deadlock_lock, 1);
debug_show_held_locks(current);
debug_show_held_locks(task);
printk("\n%s/%d's [blocked] stackdump:\n\n", task->comm, task->pid);
show_stack(task, NULL);
printk("\n%s/%d's [current] stackdump:\n\n",
current->comm, current->pid);
dump_stack();
debug_show_all_locks();
printk("[ turning off deadlock detection."
"Please report this trace. ]\n\n");
local_irq_disable();
}
void debug_rt_mutex_lock(struct rt_mutex *lock)
{
}
void debug_rt_mutex_unlock(struct rt_mutex *lock)
{
TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
}
void
debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
{
}
void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
{
TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
}
void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
{
memset(waiter, 0x11, sizeof(*waiter));
plist_node_init(&waiter->list_entry, MAX_PRIO);
plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
}
void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
{
TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
TRACE_WARN_ON(waiter->task);
memset(waiter, 0x22, sizeof(*waiter));
}
void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
{
/*
* Make sure we are not reinitializing a held lock:
*/
debug_check_no_locks_freed((void *)lock, sizeof(*lock));
lock->name = name;
}
void
rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
{
}
void rt_mutex_deadlock_account_unlock(struct task_struct *task)
{
}
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