--- /dev/null
+/*
+ * 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/config.h>
+#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 "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); \
+ if (spin_is_locked(¤t->held_list_lock)) \
+ spin_unlock(¤t->held_list_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(task_t *p)
+{
+ if (p)
+ printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
+ else
+ printk("<none>");
+}
+
+static void printk_task_short(task_t *p)
+{
+ if (p)
+ printk("%s/%d [%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");
+ }
+ if (rt_mutex_owner(lock)) {
+ printk("... acquired at: ");
+ print_symbol("%s\n", lock->acquire_ip);
+ }
+}
+
+static void printk_waiter(struct rt_mutex_waiter *w)
+{
+ printk("-------------------------\n");
+ printk("| waiter struct %p:\n", w);
+ printk("| w->list_entry: [DP:%p/%p|SP:%p/%p|PRI:%d]\n",
+ w->list_entry.plist.prio_list.prev, w->list_entry.plist.prio_list.next,
+ w->list_entry.plist.node_list.prev, w->list_entry.plist.node_list.next,
+ w->list_entry.prio);
+ printk("| w->pi_list_entry: [DP:%p/%p|SP:%p/%p|PRI:%d]\n",
+ w->pi_list_entry.plist.prio_list.prev, w->pi_list_entry.plist.prio_list.next,
+ w->pi_list_entry.plist.node_list.prev, w->pi_list_entry.plist.node_list.next,
+ w->pi_list_entry.prio);
+ printk("\n| lock:\n");
+ printk_lock(w->lock, 1);
+ printk("| w->ti->task:\n");
+ printk_task(w->task);
+ printk("| blocked at: ");
+ print_symbol("%s\n", w->ip);
+ printk("-------------------------\n");
+}
+
+static void show_task_locks(task_t *p)
+{
+ switch (p->state) {
+ case TASK_RUNNING: printk("R"); break;
+ case TASK_INTERRUPTIBLE: printk("S"); break;
+ case TASK_UNINTERRUPTIBLE: printk("D"); break;
+ case TASK_STOPPED: printk("T"); break;
+ case EXIT_ZOMBIE: printk("Z"); break;
+ case EXIT_DEAD: printk("X"); break;
+ default: printk("?"); break;
+ }
+ printk_task(p);
+ if (p->pi_blocked_on) {
+ struct rt_mutex *lock = p->pi_blocked_on->lock;
+
+ printk(" blocked on:");
+ printk_lock(lock, 1);
+ } else
+ printk(" (not blocked)\n");
+}
+
+void rt_mutex_show_held_locks(task_t *task, int verbose)
+{
+ struct list_head *curr, *cursor = NULL;
+ struct rt_mutex *lock;
+ task_t *t;
+ unsigned long flags;
+ int count = 0;
+
+ if (!rt_trace_on)
+ return;
+
+ if (verbose) {
+ printk("------------------------------\n");
+ printk("| showing all locks held by: | (");
+ printk_task_short(task);
+ printk("):\n");
+ printk("------------------------------\n");
+ }
+
+next:
+ spin_lock_irqsave(&task->held_list_lock, flags);
+ list_for_each(curr, &task->held_list_head) {
+ if (cursor && curr != cursor)
+ continue;
+ lock = list_entry(curr, struct rt_mutex, held_list_entry);
+ t = rt_mutex_owner(lock);
+ WARN_ON(t != task);
+ count++;
+ cursor = curr->next;
+ spin_unlock_irqrestore(&task->held_list_lock, flags);
+
+ printk("\n#%03d: ", count);
+ printk_lock(lock, 0);
+ goto next;
+ }
+ spin_unlock_irqrestore(&task->held_list_lock, flags);
+
+ printk("\n");
+}
+
+void rt_mutex_show_all_locks(void)
+{
+ task_t *g, *p;
+ int count = 10;
+ int unlock = 1;
+
+ printk("\n");
+ printk("----------------------\n");
+ printk("| showing all tasks: |\n");
+ printk("----------------------\n");
+
+ /*
+ * Here we try to get the tasklist_lock as hard as possible,
+ * if not successful after 2 seconds we ignore it (but keep
+ * trying). This is to enable a debug printout even if a
+ * tasklist_lock-holding task deadlocks or crashes.
+ */
+retry:
+ if (!read_trylock(&tasklist_lock)) {
+ if (count == 10)
+ printk("hm, tasklist_lock locked, retrying... ");
+ if (count) {
+ count--;
+ printk(" #%d", 10-count);
+ mdelay(200);
+ goto retry;
+ }
+ printk(" ignoring it.\n");
+ unlock = 0;
+ }
+ if (count != 10)
+ printk(" locked it.\n");
+
+ do_each_thread(g, p) {
+ show_task_locks(p);
+ if (!unlock)
+ if (read_trylock(&tasklist_lock))
+ unlock = 1;
+ } while_each_thread(g, p);
+
+ printk("\n");
+
+ printk("-----------------------------------------\n");
+ printk("| showing all locks held in the system: |\n");
+ printk("-----------------------------------------\n");
+
+ do_each_thread(g, p) {
+ rt_mutex_show_held_locks(p, 0);
+ if (!unlock)
+ if (read_trylock(&tasklist_lock))
+ unlock = 1;
+ } while_each_thread(g, p);
+
+
+ printk("=============================================\n\n");
+
+ if (unlock)
+ read_unlock(&tasklist_lock);
+}
+
+void rt_mutex_debug_check_no_locks_held(task_t *task)
+{
+ struct rt_mutex_waiter *w;
+ struct list_head *curr;
+ struct rt_mutex *lock;
+
+ if (!rt_trace_on)
+ return;
+ if (!rt_prio(task->normal_prio) && rt_prio(task->prio)) {
+ printk("BUG: PI priority boost leaked!\n");
+ printk_task(task);
+ printk("\n");
+ }
+ if (list_empty(&task->held_list_head))
+ return;
+
+ spin_lock(&task->pi_lock);
+ plist_for_each_entry(w, &task->pi_waiters, pi_list_entry) {
+ TRACE_OFF();
+
+ printk("hm, PI interest held at exit time? Task:\n");
+ printk_task(task);
+ printk_waiter(w);
+ return;
+ }
+ spin_unlock(&task->pi_lock);
+
+ list_for_each(curr, &task->held_list_head) {
+ lock = list_entry(curr, struct rt_mutex, held_list_entry);
+
+ printk("BUG: %s/%d, lock held at task exit time!\n",
+ task->comm, task->pid);
+ printk_lock(lock, 1);
+ if (rt_mutex_owner(lock) != task)
+ printk("exiting task is not even the owner??\n");
+ }
+}
+
+int rt_mutex_debug_check_no_locks_freed(const void *from, unsigned long len)
+{
+ const void *to = from + len;
+ struct list_head *curr;
+ struct rt_mutex *lock;
+ unsigned long flags;
+ void *lock_addr;
+
+ if (!rt_trace_on)
+ return 0;
+
+ spin_lock_irqsave(¤t->held_list_lock, flags);
+ list_for_each(curr, ¤t->held_list_head) {
+ lock = list_entry(curr, struct rt_mutex, held_list_entry);
+ lock_addr = lock;
+ if (lock_addr < from || lock_addr >= to)
+ continue;
+ TRACE_OFF();
+
+ printk("BUG: %s/%d, active lock [%p(%p-%p)] freed!\n",
+ current->comm, current->pid, lock, from, to);
+ dump_stack();
+ printk_lock(lock, 1);
+ if (rt_mutex_owner(lock) != current)
+ printk("freeing task is not even the owner??\n");
+ return 1;
+ }
+ spin_unlock_irqrestore(¤t->held_list_lock, flags);
+
+ return 0;
+}
+
+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("... trying at: ");
+ print_symbol("%s\n", waiter->ip);
+
+ printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);
+ printk_lock(waiter->deadlock_lock, 1);
+
+ rt_mutex_show_held_locks(current, 1);
+ rt_mutex_show_held_locks(task, 1);
+
+ 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();
+ rt_mutex_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 __IP_DECL__)
+{
+ unsigned long flags;
+
+ if (rt_trace_on) {
+ TRACE_WARN_ON_LOCKED(!list_empty(&lock->held_list_entry));
+
+ spin_lock_irqsave(¤t->held_list_lock, flags);
+ list_add_tail(&lock->held_list_entry, ¤t->held_list_head);
+ spin_unlock_irqrestore(¤t->held_list_lock, flags);
+
+ lock->acquire_ip = ip;
+ }
+}
+
+void debug_rt_mutex_unlock(struct rt_mutex *lock)
+{
+ unsigned long flags;
+
+ if (rt_trace_on) {
+ TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
+ TRACE_WARN_ON_LOCKED(list_empty(&lock->held_list_entry));
+
+ spin_lock_irqsave(¤t->held_list_lock, flags);
+ list_del_init(&lock->held_list_entry);
+ spin_unlock_irqrestore(¤t->held_list_lock, flags);
+ }
+}
+
+void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
+ struct task_struct *powner __IP_DECL__)
+{
+ unsigned long flags;
+
+ if (rt_trace_on) {
+ TRACE_WARN_ON_LOCKED(!list_empty(&lock->held_list_entry));
+
+ spin_lock_irqsave(&powner->held_list_lock, flags);
+ list_add_tail(&lock->held_list_entry, &powner->held_list_head);
+ spin_unlock_irqrestore(&powner->held_list_lock, flags);
+
+ lock->acquire_ip = ip;
+ }
+}
+
+void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
+{
+ unsigned long flags;
+
+ if (rt_trace_on) {
+ struct task_struct *owner = rt_mutex_owner(lock);
+
+ TRACE_WARN_ON_LOCKED(!owner);
+ TRACE_WARN_ON_LOCKED(list_empty(&lock->held_list_entry));
+
+ spin_lock_irqsave(&owner->held_list_lock, flags);
+ list_del_init(&lock->held_list_entry);
+ spin_unlock_irqrestore(&owner->held_list_lock, flags);
+ }
+}
+
+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)
+{
+ void *addr = lock;
+
+ if (rt_trace_on) {
+ rt_mutex_debug_check_no_locks_freed(addr,
+ sizeof(struct rt_mutex));
+ INIT_LIST_HEAD(&lock->held_list_entry);
+ lock->name = name;
+ }
+}
+
+void rt_mutex_deadlock_account_lock(struct rt_mutex *lock, task_t *task)
+{
+}
+
+void rt_mutex_deadlock_account_unlock(struct task_struct *task)
+{
+}
+
projects / linux-2.6 / commitdiff