diff options
Diffstat (limited to 'kernel/locking')
| -rw-r--r-- | kernel/locking/Makefile | 3 | ||||
| -rw-r--r-- | kernel/locking/rtmutex-debug.c | 187 | ||||
| -rw-r--r-- | kernel/locking/rtmutex-debug.h | 33 | ||||
| -rw-r--r-- | kernel/locking/rtmutex-tester.c | 420 | ||||
| -rw-r--r-- | kernel/locking/rtmutex.c | 1060 | ||||
| -rw-r--r-- | kernel/locking/rtmutex.h | 26 | ||||
| -rw-r--r-- | kernel/locking/rtmutex_common.h | 126 |
7 files changed, 1855 insertions, 0 deletions
diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile index 5978fddf1412..59f66dec2bf9 100644 --- a/kernel/locking/Makefile +++ b/kernel/locking/Makefile @@ -15,5 +15,8 @@ obj-$(CONFIG_LOCKDEP) += lockdep_proc.o endif obj-$(CONFIG_SMP) += spinlock.o obj-$(CONFIG_PROVE_LOCKING) += spinlock.o +obj-$(CONFIG_RT_MUTEXES) += rtmutex.o +obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o +obj-$(CONFIG_RT_MUTEX_TESTER) += rtmutex-tester.o obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o diff --git a/kernel/locking/rtmutex-debug.c b/kernel/locking/rtmutex-debug.c new file mode 100644 index 000000000000..13b243a323fa --- /dev/null +++ b/kernel/locking/rtmutex-debug.c @@ -0,0 +1,187 @@ +/* + * 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/sched/rt.h> +#include <linux/delay.h> +#include <linux/export.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" + +static void printk_task(struct task_struct *p) +{ + if (p) + printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), 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) +{ + DEBUG_LOCKS_WARN_ON(!plist_head_empty(&task->pi_waiters)); + DEBUG_LOCKS_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 (!debug_locks || detect || !act_waiter) + return; + + task = rt_mutex_owner(act_waiter->lock); + if (task && task != current) { + act_waiter->deadlock_task_pid = get_pid(task_pid(task)); + act_waiter->deadlock_lock = lock; + } +} + +void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter) +{ + struct task_struct *task; + + if (!waiter->deadlock_lock || !debug_locks) + return; + + rcu_read_lock(); + task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID); + if (!task) { + rcu_read_unlock(); + return; + } + + if (!debug_locks_off()) { + rcu_read_unlock(); + return; + } + + printk("\n============================================\n"); + printk( "[ BUG: circular locking deadlock detected! ]\n"); + printk("%s\n", print_tainted()); + printk( "--------------------------------------------\n"); + printk("%s/%d is deadlocking current task %s/%d\n\n", + task->comm, task_pid_nr(task), + current->comm, task_pid_nr(current)); + + printk("\n1) %s/%d is trying to acquire this lock:\n", + current->comm, task_pid_nr(current)); + printk_lock(waiter->lock, 1); + + printk("\n2) %s/%d is blocked on this lock:\n", + task->comm, task_pid_nr(task)); + 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_nr(task)); + show_stack(task, NULL); + printk("\n%s/%d's [current] stackdump:\n\n", + current->comm, task_pid_nr(current)); + dump_stack(); + debug_show_all_locks(); + rcu_read_unlock(); + + printk("[ turning off deadlock detection." + "Please report this trace. ]\n\n"); +} + +void debug_rt_mutex_lock(struct rt_mutex *lock) +{ +} + +void debug_rt_mutex_unlock(struct rt_mutex *lock) +{ + DEBUG_LOCKS_WARN_ON(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) +{ + DEBUG_LOCKS_WARN_ON(!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); + waiter->deadlock_task_pid = NULL; +} + +void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter) +{ + put_pid(waiter->deadlock_task_pid); + DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->list_entry)); + DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->pi_list_entry)); + 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) +{ +} + diff --git a/kernel/locking/rtmutex-debug.h b/kernel/locking/rtmutex-debug.h new file mode 100644 index 000000000000..14193d596d78 --- /dev/null +++ b/kernel/locking/rtmutex-debug.h @@ -0,0 +1,33 @@ +/* + * 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 file contains macros used solely by rtmutex.c. Debug version. + */ + +extern void +rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task); +extern void rt_mutex_deadlock_account_unlock(struct task_struct *task); +extern void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter); +extern void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter); +extern void debug_rt_mutex_init(struct rt_mutex *lock, const char *name); +extern void debug_rt_mutex_lock(struct rt_mutex *lock); +extern void debug_rt_mutex_unlock(struct rt_mutex *lock); +extern void debug_rt_mutex_proxy_lock(struct rt_mutex *lock, + struct task_struct *powner); +extern void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock); +extern void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *waiter, + struct rt_mutex *lock); +extern void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter); +# define debug_rt_mutex_reset_waiter(w) \ + do { (w)->deadlock_lock = NULL; } while (0) + +static inline int debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter *waiter, + int detect) +{ + return (waiter != NULL); +} diff --git a/kernel/locking/rtmutex-tester.c b/kernel/locking/rtmutex-tester.c new file mode 100644 index 000000000000..1d96dd0d93c1 --- /dev/null +++ b/kernel/locking/rtmutex-tester.c @@ -0,0 +1,420 @@ +/* + * RT-Mutex-tester: scriptable tester for rt mutexes + * + * started by Thomas Gleixner: + * + * Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com> + * + */ +#include <linux/device.h> +#include <linux/kthread.h> +#include <linux/export.h> +#include <linux/sched.h> +#include <linux/sched/rt.h> +#include <linux/spinlock.h> +#include <linux/timer.h> +#include <linux/freezer.h> +#include <linux/stat.h> + +#include "rtmutex.h" + +#define MAX_RT_TEST_THREADS 8 +#define MAX_RT_TEST_MUTEXES 8 + +static spinlock_t rttest_lock; +static atomic_t rttest_event; + +struct test_thread_data { + int opcode; + int opdata; + int mutexes[MAX_RT_TEST_MUTEXES]; + int event; + struct device dev; +}; + +static struct test_thread_data thread_data[MAX_RT_TEST_THREADS]; +static struct task_struct *threads[MAX_RT_TEST_THREADS]; +static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES]; + +enum test_opcodes { + RTTEST_NOP = 0, + RTTEST_SCHEDOT, /* 1 Sched other, data = nice */ + RTTEST_SCHEDRT, /* 2 Sched fifo, data = prio */ + RTTEST_LOCK, /* 3 Lock uninterruptible, data = lockindex */ + RTTEST_LOCKNOWAIT, /* 4 Lock uninterruptible no wait in wakeup, data = lockindex */ + RTTEST_LOCKINT, /* 5 Lock interruptible, data = lockindex */ + RTTEST_LOCKINTNOWAIT, /* 6 Lock interruptible no wait in wakeup, data = lockindex */ + RTTEST_LOCKCONT, /* 7 Continue locking after the wakeup delay */ + RTTEST_UNLOCK, /* 8 Unlock, data = lockindex */ + /* 9, 10 - reserved for BKL commemoration */ + RTTEST_SIGNAL = 11, /* 11 Signal other test thread, data = thread id */ + RTTEST_RESETEVENT = 98, /* 98 Reset event counter */ + RTTEST_RESET = 99, /* 99 Reset all pending operations */ +}; + +static int handle_op(struct test_thread_data *td, int lockwakeup) +{ + int i, id, ret = -EINVAL; + + switch(td->opcode) { + + case RTTEST_NOP: + return 0; + + case RTTEST_LOCKCONT: + td->mutexes[td->opdata] = 1; + td->event = atomic_add_return(1, &rttest_event); + return 0; + + case RTTEST_RESET: + for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) { + if (td->mutexes[i] == 4) { + rt_mutex_unlock(&mutexes[i]); + td->mutexes[i] = 0; + } + } + return 0; + + case RTTEST_RESETEVENT: + atomic_set(&rttest_event, 0); + return 0; + + default: + if (lockwakeup) + return ret; + } + + switch(td->opcode) { + + case RTTEST_LOCK: + case RTTEST_LOCKNOWAIT: + id = td->opdata; + if (id < 0 || id >= MAX_RT_TEST_MUTEXES) + return ret; + + td->mutexes[id] = 1; + td->event = atomic_add_return(1, &rttest_event); + rt_mutex_lock(&mutexes[id]); + td->event = atomic_add_return(1, &rttest_event); + td->mutexes[id] = 4; + return 0; + + case RTTEST_LOCKINT: + case RTTEST_LOCKINTNOWAIT: + id = td->opdata; + if (id < 0 || id >= MAX_RT_TEST_MUTEXES) + return ret; + + td->mutexes[id] = 1; + td->event = atomic_add_return(1, &rttest_event); + ret = rt_mutex_lock_interruptible(&mutexes[id], 0); + td->event = atomic_add_return(1, &rttest_event); + td->mutexes[id] = ret ? 0 : 4; + return ret ? -EINTR : 0; + + case RTTEST_UNLOCK: + id = td->opdata; + if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4) + return ret; + + td->event = atomic_add_return(1, &rttest_event); + rt_mutex_unlock(&mutexes[id]); + td->event = atomic_add_return(1, &rttest_event); + td->mutexes[id] = 0; + return 0; + + default: + break; + } + return ret; +} + +/* + * Schedule replacement for rtsem_down(). Only called for threads with + * PF_MUTEX_TESTER set. + * + * This allows us to have finegrained control over the event flow. + * + */ +void schedule_rt_mutex_test(struct rt_mutex *mutex) +{ + int tid, op, dat; + struct test_thread_data *td; + + /* We have to lookup the task */ + for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) { + if (threads[tid] == current) + break; + } + + BUG_ON(tid == MAX_RT_TEST_THREADS); + + td = &thread_data[tid]; + + op = td->opcode; + dat = td->opdata; + + switch (op) { + case RTTEST_LOCK: + case RTTEST_LOCKINT: + case RTTEST_LOCKNOWAIT: + case RTTEST_LOCKINTNOWAIT: + if (mutex != &mutexes[dat]) + break; + + if (td->mutexes[dat] != 1) + break; + + td->mutexes[dat] = 2; + td->event = atomic_add_return(1, &rttest_event); + break; + + default: + break; + } + + schedule(); + + + switch (op) { + case RTTEST_LOCK: + case RTTEST_LOCKINT: + if (mutex != &mutexes[dat]) + return; + + if (td->mutexes[dat] != 2) + return; + + td->mutexes[dat] = 3; + td->event = atomic_add_return(1, &rttest_event); + break; + + case RTTEST_LOCKNOWAIT: + case RTTEST_LOCKINTNOWAIT: + if (mutex != &mutexes[dat]) + return; + + if (td->mutexes[dat] != 2) + return; + + td->mutexes[dat] = 1; + td->event = atomic_add_return(1, &rttest_event); + return; + + default: + return; + } + + td->opcode = 0; + + for (;;) { + set_current_state(TASK_INTERRUPTIBLE); + + if (td->opcode > 0) { + int ret; + + set_current_state(TASK_RUNNING); + ret = handle_op(td, 1); + set_current_state(TASK_INTERRUPTIBLE); + if (td->opcode == RTTEST_LOCKCONT) + break; + td->opcode = ret; + } + + /* Wait for the next command to be executed */ + schedule(); + } + + /* Restore previous command and data */ + td->opcode = op; + td->opdata = dat; +} + +static int test_func(void *data) +{ + struct test_thread_data *td = data; + int ret; + + current->flags |= PF_MUTEX_TESTER; + set_freezable(); + allow_signal(SIGHUP); + + for(;;) { + + set_current_state(TASK_INTERRUPTIBLE); + + if (td->opcode > 0) { + set_current_state(TASK_RUNNING); + ret = handle_op(td, 0); + set_current_state(TASK_INTERRUPTIBLE); + td->opcode = ret; + } + + /* Wait for the next command to be executed */ + schedule(); + try_to_freeze(); + + if (signal_pending(current)) + flush_signals(current); + + if(kthread_should_stop()) + break; + } + return 0; +} + +/** + * sysfs_test_command - interface for test commands + * @dev: thread reference + * @buf: command for actual step + * @count: length of buffer + * + * command syntax: + * + * opcode:data + */ +static ssize_t sysfs_test_command(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct sched_param schedpar; + struct test_thread_data *td; + char cmdbuf[32]; + int op, dat, tid, ret; + + td = container_of(dev, struct test_thread_data, dev); + tid = td->dev.id; + + /* strings from sysfs write are not 0 terminated! */ + if (count >= sizeof(cmdbuf)) + return -EINVAL; + + /* strip of \n: */ + if (buf[count-1] == '\n') + count--; + if (count < 1) + return -EINVAL; + + memcpy(cmdbuf, buf, count); + cmdbuf[count] = 0; + + if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2) + return -EINVAL; + + switch (op) { + case RTTEST_SCHEDOT: + schedpar.sched_priority = 0; + ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar); + if (ret) + return ret; + set_user_nice(current, 0); + break; + + case RTTEST_SCHEDRT: + schedpar.sched_priority = dat; + ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar); + if (ret) + return ret; + break; + + case RTTEST_SIGNAL: + send_sig(SIGHUP, threads[tid], 0); + break; + + default: + if (td->opcode > 0) + return -EBUSY; + td->opdata = dat; + td->opcode = op; + wake_up_process(threads[tid]); + } + + return count; +} + +/** + * sysfs_test_status - sysfs interface for rt tester + * @dev: thread to query + * @buf: char buffer to be filled with thread status info + */ +static ssize_t sysfs_test_status(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct test_thread_data *td; + struct task_struct *tsk; + char *curr = buf; + int i; + + td = container_of(dev, struct test_thread_data, dev); + tsk = threads[td->dev.id]; + + spin_lock(&rttest_lock); + + curr += sprintf(curr, + "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, M:", + td->opcode, td->event, tsk->state, + (MAX_RT_PRIO - 1) - tsk->prio, + (MAX_RT_PRIO - 1) - tsk->normal_prio, + tsk->pi_blocked_on); + + for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--) + curr += sprintf(curr, "%d", td->mutexes[i]); + + spin_unlock(&rttest_lock); + + curr += sprintf(curr, ", T: %p, R: %p\n", tsk, + mutexes[td->dev.id].owner); + + return curr - buf; +} + +static DEVICE_ATTR(status, S_IRUSR, sysfs_test_status, NULL); +static DEVICE_ATTR(command, S_IWUSR, NULL, sysfs_test_command); + +static struct bus_type rttest_subsys = { + .name = "rttest", + .dev_name = "rttest", +}; + +static int init_test_thread(int id) +{ + thread_data[id].dev.bus = &rttest_subsys; + thread_data[id].dev.id = id; + + threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id); + if (IS_ERR(threads[id])) + return PTR_ERR(threads[id]); + + return device_register(&thread_data[id].dev); +} + +static int init_rttest(void) +{ + int ret, i; + + spin_lock_init(&rttest_lock); + + for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) + rt_mutex_init(&mutexes[i]); + + ret = subsys_system_register(&rttest_subsys, NULL); + if (ret) + return ret; + + for (i = 0; i < MAX_RT_TEST_THREADS; i++) { + ret = init_test_thread(i); + if (ret) + break; + ret = device_create_file(&thread_data[i].dev, &dev_attr_status); + if (ret) + break; + ret = device_create_file(&thread_data[i].dev, &dev_attr_command); + if (ret) + break; + } + + printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" ); + + return ret; +} + +device_initcall(init_rttest); diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c new file mode 100644 index 000000000000..0dd6aec1cb6a --- /dev/null +++ b/kernel/locking/rtmutex.c @@ -0,0 +1,1060 @@ +/* + * RT-Mutexes: simple 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) 2005-2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com> + * Copyright (C) 2005 Kihon Technologies Inc., Steven Rostedt + * Copyright (C) 2006 Esben Nielsen + * + * See Documentation/rt-mutex-design.txt for details. + */ +#include <linux/spinlock.h> +#include <linux/export.h> +#include <linux/sched.h> +#include <linux/sched/rt.h> +#include <linux/timer.h> + +#include "rtmutex_common.h" + +/* + * lock->owner state tracking: + * + * lock->owner holds the task_struct pointer of the owner. Bit 0 + * is used to keep track of the "lock has waiters" state. + * + * owner bit0 + * NULL 0 lock is free (fast acquire possible) + * NULL 1 lock is free and has waiters and the top waiter + * is going to take the lock* + * taskpointer 0 lock is held (fast release possible) + * taskpointer 1 lock is held and has waiters** + * + * The fast atomic compare exchange based acquire and release is only + * possible when bit 0 of lock->owner is 0. + * + * (*) It also can be a transitional state when grabbing the lock + * with ->wait_lock is held. To prevent any fast path cmpxchg to the lock, + * we need to set the bit0 before looking at the lock, and the owner may be + * NULL in this small time, hence this can be a transitional state. + * + * (**) There is a small time when bit 0 is set but there are no + * waiters. This can happen when grabbing the lock in the slow path. + * To prevent a cmpxchg of the owner releasing the lock, we need to + * set this bit before looking at the lock. + */ + +static void +rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner) +{ + unsigned long val = (unsigned long)owner; + + if (rt_mutex_has_waiters(lock)) + val |= RT_MUTEX_HAS_WAITERS; + + lock->owner = (struct task_struct *)val; +} + +static inline void clear_rt_mutex_waiters(struct rt_mutex *lock) +{ + lock->owner = (struct task_struct *) + ((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS); +} + +static void fixup_rt_mutex_waiters(struct rt_mutex *lock) +{ + if (!rt_mutex_has_waiters(lock)) + clear_rt_mutex_waiters(lock); +} + +/* + * We can speed up the acquire/release, if the architecture + * supports cmpxchg and if there's no debugging state to be set up + */ +#if defined(__HAVE_ARCH_CMPXCHG) && !defined(CONFIG_DEBUG_RT_MUTEXES) +# define rt_mutex_cmpxchg(l,c,n) (cmpxchg(&l->owner, c, n) == c) +static inline void mark_rt_mutex_waiters(struct rt_mutex *lock) +{ + unsigned long owner, *p = (unsigned long *) &lock->owner; + + do { + owner = *p; + } while (cmpxchg(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner); +} +#else +# define rt_mutex_cmpxchg(l,c,n) (0) +static inline void mark_rt_mutex_waiters(struct rt_mutex *lock) +{ + lock->owner = (struct task_struct *) + ((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS); +} +#endif + +/* + * Calculate task priority from the waiter list priority + * + * Return task->normal_prio when the waiter list is empty or when + * the waiter is not allowed to do priority boosting + */ +int rt_mutex_getprio(struct task_struct *task) +{ + if (likely(!task_has_pi_waiters(task))) + return task->normal_prio; + + return min(task_top_pi_waiter(task)->pi_list_entry.prio, + task->normal_prio); +} + +/* + * Adjust the priority of a task, after its pi_waiters got modified. + * + * This can be both boosting and unboosting. task->pi_lock must be held. + */ +static void __rt_mutex_adjust_prio(struct task_struct *task) +{ + int prio = rt_mutex_getprio(task); + + if (task->prio != prio) + rt_mutex_setprio(task, prio); +} + +/* + * Adjust task priority (undo boosting). Called from the exit path of + * rt_mutex_slowunlock() and rt_mutex_slowlock(). + * + * (Note: We do this outside of the protection of lock->wait_lock to + * allow the lock to be taken while or before we readjust the priority + * of task. We do not use the spin_xx_mutex() variants here as we are + * outside of the debug path.) + */ +static void rt_mutex_adjust_prio(struct task_struct *task) +{ + unsigned long flags; + + raw_spin_lock_irqsave(&task->pi_lock, flags); + __rt_mutex_adjust_prio(task); + raw_spin_unlock_irqrestore(&task->pi_lock, flags); +} + +/* + * Max number of times we'll walk the boosting chain: + */ +int max_lock_depth = 1024; + +/* + * Adjust the priority chain. Also used for deadlock detection. + * Decreases task's usage by one - may thus free the task. + * + * @task: the task owning the mutex (owner) for which a chain walk is probably + * needed + * @deadlock_detect: do we have to carry out deadlock detection? + * @orig_lock: the mutex (can be NULL if we are walking the chain to recheck + * things for a task that has just got its priority adjusted, and + * is waiting on a mutex) + * @orig_waiter: rt_mutex_waiter struct for the task that has just donated + * its priority to the mutex owner (can be NULL in the case + * depicted above or if the top waiter is gone away and we are + * actually deboosting the owner) + * @top_task: the current top waiter + * + * Returns 0 or -EDEADLK. + */ +static int rt_mutex_adjust_prio_chain(struct task_struct *task, + int deadlock_detect, + struct rt_mutex *orig_lock, + struct rt_mutex_waiter *orig_waiter, + struct task_struct *top_task) +{ + struct rt_mutex *lock; + struct rt_mutex_waiter *waiter, *top_waiter = orig_waiter; + int detect_deadlock, ret = 0, depth = 0; + unsigned long flags; + + detect_deadlock = debug_rt_mutex_detect_deadlock(orig_waiter, + deadlock_detect); + + /* + * The (de)boosting is a step by step approach with a lot of + * pitfalls. We want this to be preemptible and we want hold a + * maximum of two locks per step. So we have to check + * carefully whether things change under us. + */ + again: + if (++depth > max_lock_depth) { + static int prev_max; + + /* + * Print this only once. If the admin changes the limit, + * print a new message when reaching the limit again. + */ + if (prev_max != max_lock_depth) { + prev_max = max_lock_depth; + printk(KERN_WARNING "Maximum lock depth %d reached " + "task: %s (%d)\n", max_lock_depth, + top_task->comm, task_pid_nr(top_task)); + } + put_task_struct(task); + + return deadlock_detect ? -EDEADLK : 0; + } + retry: + /* + * Task can not go away as we did a get_task() before ! + */ + raw_spin_lock_irqsave(&task->pi_lock, flags); + + waiter = task->pi_blocked_on; + /* + * Check whether the end of the boosting chain has been + * reached or the state of the chain has changed while we + * dropped the locks. + */ + if (!waiter) + goto out_unlock_pi; + + /* + * Check the orig_waiter state. After we dropped the locks, + * the previous owner of the lock might have released the lock. + */ + if (orig_waiter && !rt_mutex_owner(orig_lock)) + goto out_unlock_pi; + + /* + * Drop out, when the task has no waiters. Note, + * top_waiter can be NULL, when we are in the deboosting + * mode! + */ + if (top_waiter && (!task_has_pi_waiters(task) || + top_waiter != task_top_pi_waiter(task))) + goto out_unlock_pi; + + /* + * When deadlock detection is off then we check, if further + * priority adjustment is necessary. + */ + if (!detect_deadlock && waiter->list_entry.prio == task->prio) + goto out_unlock_pi; + + lock = waiter->lock; + if (!raw_spin_trylock(&lock->wait_lock)) { + raw_spin_unlock_irqrestore(&task->pi_lock, flags); + cpu_relax(); + goto retry; + } + + /* Deadlock detection */ + if (lock == orig_lock || rt_mutex_owner(lock) == top_task) { + debug_rt_mutex_deadlock(deadlock_detect, orig_waiter, lock); + raw_spin_unlock(&lock->wait_lock); + ret = deadlock_detect ? -EDEADLK : 0; + goto out_unlock_pi; + } + + top_waiter = rt_mutex_top_waiter(lock); + + /* Requeue the waiter */ + plist_del(&waiter->list_entry, &lock->wait_list); + waiter->list_entry.prio = task->prio; + plist_add(&waiter->list_entry, &lock->wait_list); + + /* Release the task */ + raw_spin_unlock_irqrestore(&task->pi_lock, flags); + if (!rt_mutex_owner(lock)) { + /* + * If the requeue above changed the top waiter, then we need + * to wake the new top waiter up to try to get the lock. + */ + + if (top_waiter != rt_mutex_top_waiter(lock)) + wake_up_process(rt_mutex_top_waiter(lock)->task); + raw_spin_unlock(&lock->wait_lock); + goto out_put_task; + } + put_task_struct(task); + + /* Grab the next task */ + task = rt_mutex_owner(lock); + get_task_struct(task); + raw_spin_lock_irqsave(&task->pi_lock, flags); + + if (waiter == rt_mutex_top_waiter(lock)) { + /* Boost the owner */ + plist_del(&top_waiter->pi_list_entry, &task->pi_waiters); + waiter->pi_list_entry.prio = waiter->list_entry.prio; + plist_add(&waiter->pi_list_entry, &task->pi_waiters); + __rt_mutex_adjust_prio(task); + + } else if (top_waiter == waiter) { + /* Deboost the owner */ + plist_del(&waiter->pi_list_entry, &task->pi_waiters); + waiter = rt_mutex_top_waiter(lock); + waiter->pi_list_entry.prio = waiter->list_entry.prio; + plist_add(&waiter->pi_list_entry, &task->pi_waiters); + __rt_mutex_adjust_prio(task); + } + + raw_spin_unlock_irqrestore(&task->pi_lock, flags); + + top_waiter = rt_mutex_top_waiter(lock); + raw_spin_unlock(&lock->wait_lock); + + if (!detect_deadlock && waiter != top_waiter) + goto out_put_task; + + goto again; + + out_unlock_pi: + raw_spin_unlock_irqrestore(&task->pi_lock, flags); + out_put_task: + put_task_struct(task); + + return ret; +} + +/* + * Try to take an rt-mutex + * + * Must be called with lock->wait_lock held. + * + * @lock: the lock to be acquired. + * @task: the task which wants to acquire the lock + * @waiter: the waiter that is queued to the lock's wait list. (could be NULL) + */ +static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task, + struct rt_mutex_waiter *waiter) +{ + /* + * We have to be careful here if the atomic speedups are + * enabled, such that, when + * - no other waiter is on the lock + * - the lock has been released since we did the cmpxchg + * the lock can be released or taken while we are doing the + * checks and marking the lock with RT_MUTEX_HAS_WAITERS. + * + * The atomic acquire/release aware variant of + * mark_rt_mutex_waiters uses a cmpxchg loop. After setting + * the WAITERS bit, the atomic release / acquire can not + * happen anymore and lock->wait_lock protects us from the + * non-atomic case. + * + * Note, that this might set lock->owner = + * RT_MUTEX_HAS_WAITERS in the case the lock is not contended + * any more. This is fixed up when we take the ownership. + * This is the transitional state explained at the top of this file. + */ + mark_rt_mutex_waiters(lock); + + if (rt_mutex_owner(lock)) + return 0; + + /* + * It will get the lock because of one of these conditions: + * 1) there is no waiter + * 2) higher priority than waiters + * 3) it is top waiter + */ + if (rt_mutex_has_waiters(lock)) { + if (task->prio >= rt_mutex_top_waiter(lock)->list_entry.prio) { + if (!waiter || waiter != rt_mutex_top_waiter(lock)) + return 0; + } + } + + if (waiter || rt_mutex_has_waiters(lock)) { + unsigned long flags; + struct rt_mutex_waiter *top; + + raw_spin_lock_irqsave(&task->pi_lock, flags); + + /* remove the queued waiter. */ + if (waiter) { + plist_del(&waiter->list_entry, &lock->wait_list); + task->pi_blocked_on = NULL; + } + + /* + * We have to enqueue the top waiter(if it exists) into + * task->pi_waiters list. + */ + if (rt_mutex_has_waiters(lock)) { + top = rt_mutex_top_waiter(lock); + top->pi_list_entry.prio = top->list_entry.prio; + plist_add(&top->pi_list_entry, &task->pi_waiters); + } + raw_spin_unlock_irqrestore(&task->pi_lock, flags); + } + + /* We got the lock. */ + debug_rt_mutex_lock(lock); + + rt_mutex_set_owner(lock, task); + + rt_mutex_deadlock_account_lock(lock, task); + + return 1; +} + +/* + * Task blocks on lock. + * + * Prepare waiter and propagate pi chain + * + * This must be called with lock->wait_lock held. + */ +static int task_blocks_on_rt_mutex(struct rt_mutex *lock, + struct rt_mutex_waiter *waiter, + struct task_struct *task, + int detect_deadlock) +{ + struct task_struct *owner = rt_mutex_owner(lock); + struct rt_mutex_waiter *top_waiter = waiter; + unsigned long flags; + int chain_walk = 0, res; + + raw_spin_lock_irqsave(&task->pi_lock, flags); + __rt_mutex_adjust_prio(task); + waiter->task = task; + waiter->lock = lock; + plist_node_init(&waiter->list_entry, task->prio); + plist_node_init(&waiter->pi_list_entry, task->prio); + + /* Get the top priority waiter on the lock */ + if (rt_mutex_has_waiters(lock)) + top_waiter = rt_mutex_top_waiter(lock); + plist_add(&waiter->list_entry, &lock->wait_list); + + task->pi_blocked_on = waiter; + + raw_spin_unlock_irqrestore(&task->pi_lock, flags); + + if (!owner) + return 0; + + if (waiter == rt_mutex_top_waiter(lock)) { + raw_spin_lock_irqsave(&owner->pi_lock, flags); + plist_del(&top_waiter->pi_list_entry, &owner->pi_waiters); + plist_add(&waiter->pi_list_entry, &owner->pi_waiters); + + __rt_mutex_adjust_prio(owner); + if (owner->pi_blocked_on) + chain_walk = 1; + raw_spin_unlock_irqrestore(&owner->pi_lock, flags); + } + else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock)) + chain_walk = 1; + + if (!chain_walk) + return 0; + + /* + * The owner can't disappear while holding a lock, + * so the owner struct is protected by wait_lock. + * Gets dropped in rt_mutex_adjust_prio_chain()! + */ + get_task_struct(owner); + + raw_spin_unlock(&lock->wait_lock); + + res = rt_mutex_adjust_prio_chain(owner, detect_deadlock, lock, waiter, + task); + + raw_spin_lock(&lock->wait_lock); + + return res; +} + +/* + * Wake up the next waiter on the lock. + * + * Remove the top waiter from the current tasks waiter list and wake it up. + * + * Called with lock->wait_lock held. + */ +static void wakeup_next_waiter(struct rt_mutex *lock) +{ + struct rt_mutex_waiter *waiter; + unsigned long flags; + + raw_spin_lock_irqsave(¤t->pi_lock, flags); + + waiter = rt_mutex_top_waiter(lock); + + /* + * Remove it from current->pi_waiters. We do not adjust a + * possible priority boost right now. We execute wakeup in the + * boosted mode and go back to normal after releasing + * lock->wait_lock. + */ + plist_del(&waiter->pi_list_entry, ¤t->pi_waiters); + + rt_mutex_set_owner(lock, NULL); + + raw_spin_unlock_irqrestore(¤t->pi_lock, flags); + + wake_up_process(waiter->task); +} + +/* + * Remove a waiter from a lock and give up + * + * Must be called with lock->wait_lock held and + * have just failed to try_to_take_rt_mutex(). + */ +static void remove_waiter(struct rt_mutex *lock, + struct rt_mutex_waiter *waiter) +{ + int first = (waiter == rt_mutex_top_waiter(lock)); + struct task_struct *owner = rt_mutex_owner(lock); + unsigned long flags; + int chain_walk = 0; + + raw_spin_lock_irqsave(¤t->pi_lock, flags); + plist_del(&waiter->list_entry, &lock->wait_list); + current->pi_blocked_on = NULL; + raw_spin_unlock_irqrestore(¤t->pi_lock, flags); + + if (!owner) + return; + + if (first) { + + raw_spin_lock_irqsave(&owner->pi_lock, flags); + + plist_del(&waiter->pi_list_entry, &owner->pi_waiters); + + if (rt_mutex_has_waiters(lock)) { + struct rt_mutex_waiter *next; + + next = rt_mutex_top_waiter(lock); + plist_add(&next->pi_list_entry, &owner->pi_waiters); + } + __rt_mutex_adjust_prio(owner); + + if (owner->pi_blocked_on) + chain_walk = 1; + + raw_spin_unlock_irqrestore(&owner->pi_lock, flags); + } + + WARN_ON(!plist_node_empty(&waiter->pi_list_entry)); + + if (!chain_walk) + return; + + /* gets dropped in rt_mutex_adjust_prio_chain()! */ + get_task_struct(owner); + + raw_spin_unlock(&lock->wait_lock); + + rt_mutex_adjust_prio_chain(owner, 0, lock, NULL, current); + + raw_spin_lock(&lock->wait_lock); +} + +/* + * Recheck the pi chain, in case we got a priority setting + * + * Called from sched_setscheduler + */ +void rt_mutex_adjust_pi(struct task_struct *task) +{ + struct rt_mutex_waiter *waiter; + unsigned long flags; + + raw_spin_lock_irqsave(&task->pi_lock, flags); + + waiter = task->pi_blocked_on; + if (!waiter || waiter->list_entry.prio == task->prio) { + raw_spin_unlock_irqrestore(&task->pi_lock, flags); + return; + } + + raw_spin_unlock_irqrestore(&task->pi_lock, flags); + + /* gets dropped in rt_mutex_adjust_prio_chain()! */ + get_task_struct(task); + rt_mutex_adjust_prio_chain(task, 0, NULL, NULL, task); +} + +/** + * __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop + * @lock: the rt_mutex to take + * @state: the state the task should block in (TASK_INTERRUPTIBLE + * or TASK_UNINTERRUPTIBLE) + * @timeout: the pre-initialized and started timer, or NULL for none + * @waiter: the pre-initialized rt_mutex_waiter + * + * lock->wait_lock must be held by the caller. + */ +static int __sched +__rt_mutex_slowlock(struct rt_mutex *lock, int state, + struct hrtimer_sleeper *timeout, + struct rt_mutex_waiter *waiter) +{ + int ret = 0; + + for (;;) { + /* Try to acquire the lock: */ + if (try_to_take_rt_mutex(lock, current, waiter)) + break; + + /* + * TASK_INTERRUPTIBLE checks for signals and + * timeout. Ignored otherwise. + */ + if (unlikely(state == TASK_INTERRUPTIBLE)) { + /* Signal pending? */ + if (signal_pending(current)) + ret = -EINTR; + if (timeout && !timeout->task) + ret = -ETIMEDOUT; + if (ret) + break; + } + + raw_spin_unlock(&lock->wait_lock); + + debug_rt_mutex_print_deadlock(waiter); + + schedule_rt_mutex(lock); + + raw_spin_lock(&lock->wait_lock); + set_current_state(state); + } + + return ret; +} + +/* + * Slow path lock function: + */ +static int __sched +rt_mutex_slowlock(struct rt_mutex *lock, int state, + struct hrtimer_sleeper *timeout, + int detect_deadlock) +{ + struct rt_mutex_waiter waiter; + int ret = 0; + + debug_rt_mutex_init_waiter(&waiter); + + raw_spin_lock(&lock->wait_lock); + + /* Try to acquire the lock again: */ + if (try_to_take_rt_mutex(lock, current, NULL)) { + raw_spin_unlock(&lock->wait_lock); + return 0; + } + + set_current_state(state); + + /* Setup the timer, when timeout != NULL */ + if (unlikely(timeout)) { + hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS); + if (!hrtimer_active(&timeout->timer)) + timeout->task = NULL; + } + + ret = task_blocks_on_rt_mutex(lock, &waiter, current, detect_deadlock); + + if (likely(!ret)) + ret = __rt_mutex_slowlock(lock, state, timeout, &waiter); + + set_current_state(TASK_RUNNING); + + if (unlikely(ret)) + remove_waiter(lock, &waiter); + + /* + * try_to_take_rt_mutex() sets the waiter bit + * unconditionally. We might have to fix that up. + */ + fixup_rt_mutex_waiters(lock); + + raw_spin_unlock(&lock->wait_lock); + + /* Remove pending timer: */ + if (unlikely(timeout)) + hrtimer_cancel(&timeout->timer); + + debug_rt_mutex_free_waiter(&waiter); + + return ret; +} + +/* + * Slow path try-lock function: + */ +static inline int +rt_mutex_slowtrylock(struct rt_mutex *lock) +{ + int ret = 0; + + raw_spin_lock(&lock->wait_lock); + + if (likely(rt_mutex_owner(lock) != current)) { + + ret = try_to_take_rt_mutex(lock, current, NULL); + /* + * try_to_take_rt_mutex() sets the lock waiters + * bit unconditionally. Clean this up. + */ + fixup_rt_mutex_waiters(lock); + } + + raw_spin_unlock(&lock->wait_lock); + + return ret; +} + +/* + * Slow path to release a rt-mutex: + */ +static void __sched +rt_mutex_slowunlock(struct rt_mutex *lock) +{ + raw_spin_lock(&lock->wait_lock); + + debug_rt_mutex_unlock(lock); + + rt_mutex_deadlock_account_unlock(current); + + if (!rt_mutex_has_waiters(lock)) { + lock->owner = NULL; + raw_spin_unlock(&lock->wait_lock); + return; + } + + wakeup_next_waiter(lock); + + raw_spin_unlock(&lock->wait_lock); + + /* Undo pi boosting if necessary: */ + rt_mutex_adjust_prio(current); +} + +/* + * debug aware fast / slowpath lock,trylock,unlock + * + * The atomic acquire/release ops are compiled away, when either the + * architecture does not support cmpxchg or when debugging is enabled. + */ +static inline int +rt_mutex_fastlock(struct rt_mutex *lock, int state, + int detect_deadlock, + int (*slowfn)(struct rt_mutex *lock, int state, + struct hrtimer_sleeper *timeout, + int detect_deadlock)) +{ + if (!detect_deadlock && likely(rt_mutex_cmpxchg(lock, NULL, current))) { + rt_mutex_deadlock_account_lock(lock, current); + return 0; + } else + return slowfn(lock, state, NULL, detect_deadlock); +} + +static inline int +rt_mutex_timed_fastlock(struct rt_mutex *lock, int state, + struct hrtimer_sleeper *timeout, int detect_deadlock, + int (*slowfn)(struct rt_mutex *lock, int state, + struct hrtimer_sleeper *timeout, + int detect_deadlock)) +{ + if (!detect_deadlock && likely(rt_mutex_cmpxchg(lock, NULL, current))) { + rt_mutex_deadlock_account_lock(lock, current); + return 0; + } else + return slowfn(lock, state, timeout, detect_deadlock); +} + +static inline int +rt_mutex_fasttrylock(struct rt_mutex *lock, + int (*slowfn)(struct rt_mutex *lock)) +{ + if (likely(rt_mutex_cmpxchg(lock, NULL, current))) { + rt_mutex_deadlock_account_lock(lock, current); + return 1; + } + return slowfn(lock); +} + +static inline void +rt_mutex_fastunlock(struct rt_mutex *lock, + void (*slowfn)(struct rt_mutex *lock)) +{ + if (likely(rt_mutex_cmpxchg(lock, current, NULL))) + rt_mutex_deadlock_account_unlock(current); + else + slowfn(lock); +} + +/** + * rt_mutex_lock - lock a rt_mutex + * + * @lock: the rt_mutex to be locked + */ +void __sched rt_mutex_lock(struct rt_mutex *lock) +{ + might_sleep(); + + rt_mutex_fastlock(lock, TASK_UNINTERRUPTIBLE, 0, rt_mutex_slowlock); +} +EXPORT_SYMBOL_GPL(rt_mutex_lock); + +/** + * rt_mutex_lock_interruptible - lock a rt_mutex interruptible + * + * @lock: the rt_mutex to be locked + * @detect_deadlock: deadlock detection on/off + * + * Returns: + * 0 on success + * -EINTR when interrupted by a signal + * -EDEADLK when the lock would deadlock (when deadlock detection is on) + */ +int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock, + int detect_deadlock) +{ + might_sleep(); + + return rt_mutex_fastlock(lock, TASK_INTERRUPTIBLE, + detect_deadlock, rt_mutex_slowlock); +} +EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible); + +/** + * rt_mutex_timed_lock - lock a rt_mutex interruptible + * the timeout structure is provided + * by the caller + * + * @lock: the rt_mutex to be locked + * @timeout: timeout structure or NULL (no timeout) + * @detect_deadlock: deadlock detection on/off + * + * Returns: + * 0 on success + * -EINTR when interrupted by a signal + * -ETIMEDOUT when the timeout expired + * -EDEADLK when the lock would deadlock (when deadlock detection is on) + */ +int +rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout, + int detect_deadlock) +{ + might_sleep(); + + return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout, + detect_deadlock, rt_mutex_slowlock); +} +EXPORT_SYMBOL_GPL(rt_mutex_timed_lock); + +/** + * rt_mutex_trylock - try to lock a rt_mutex + * + * @lock: the rt_mutex to be locked + * + * Returns 1 on success and 0 on contention + */ +int __sched rt_mutex_trylock(struct rt_mutex *lock) +{ + return rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock); +} +EXPORT_SYMBOL_GPL(rt_mutex_trylock); + +/** + * rt_mutex_unlock - unlock a rt_mutex + * + * @lock: the rt_mutex to be unlocked + */ +void __sched rt_mutex_unlock(struct rt_mutex *lock) +{ + rt_mutex_fastunlock(lock, rt_mutex_slowunlock); +} +EXPORT_SYMBOL_GPL(rt_mutex_unlock); + +/** + * rt_mutex_destroy - mark a mutex unusable + * @lock: the mutex to be destroyed + * + * This function marks the mutex uninitialized, and any subsequent + * use of the mutex is forbidden. The mutex must not be locked when + * this function is called. + */ +void rt_mutex_destroy(struct rt_mutex *lock) +{ + WARN_ON(rt_mutex_is_locked(lock)); +#ifdef CONFIG_DEBUG_RT_MUTEXES + lock->magic = NULL; +#endif +} + +EXPORT_SYMBOL_GPL(rt_mutex_destroy); + +/** + * __rt_mutex_init - initialize the rt lock + * + * @lock: the rt lock to be initialized + * + * Initialize the rt lock to unlocked state. + * + * Initializing of a locked rt lock is not allowed + */ +void __rt_mutex_init(struct rt_mutex *lock, const char *name) +{ + lock->owner = NULL; + raw_spin_lock_init(&lock->wait_lock); + plist_head_init(&lock->wait_list); + + debug_rt_mutex_init(lock, name); +} +EXPORT_SYMBOL_GPL(__rt_mutex_init); + +/** + * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a + * proxy owner + * + * @lock: the rt_mutex to be locked + * @proxy_owner:the task to set as owner + * + * No locking. Caller has to do serializing itself + * Special API call for PI-futex support + */ +void rt_mutex_init_proxy_locked(struct rt_mutex *lock, + struct task_struct *proxy_owner) +{ + __rt_mutex_init(lock, NULL); + debug_rt_mutex_proxy_lock(lock, proxy_owner); + rt_mutex_set_owner(lock, proxy_owner); + rt_mutex_deadlock_account_lock(lock, proxy_owner); +} + +/** + * rt_mutex_proxy_unlock - release a lock on behalf of owner + * + * @lock: the rt_mutex to be locked + * + * No locking. Caller has to do serializing itself + * Special API call for PI-futex support + */ +void rt_mutex_proxy_unlock(struct rt_mutex *lock, + struct task_struct *proxy_owner) +{ + debug_rt_mutex_proxy_unlock(lock); + rt_mutex_set_owner(lock, NULL); + rt_mutex_deadlock_account_unlock(proxy_owner); +} + +/** + * rt_mutex_start_proxy_lock() - Start lock acquisition for another task + * @lock: the rt_mutex to take + * @waiter: the pre-initialized rt_mutex_waiter + * @task: the task to prepare + * @detect_deadlock: perform deadlock detection (1) or not (0) + * + * Returns: + * 0 - task blocked on lock + * 1 - acquired the lock for task, caller should wake it up + * <0 - error + * + * Special API call for FUTEX_REQUEUE_PI support. + */ +int rt_mutex_start_proxy_lock(struct rt_mutex *lock, + struct rt_mutex_waiter *waiter, + struct task_struct *task, int detect_deadlock) +{ + int ret; + + raw_spin_lock(&lock->wait_lock); + + if (try_to_take_rt_mutex(lock, task, NULL)) { + raw_spin_unlock(&lock->wait_lock); + return 1; + } + + ret = task_blocks_on_rt_mutex(lock, waiter, task, detect_deadlock); + + if (ret && !rt_mutex_owner(lock)) { + /* + * Reset the return value. We might have + * returned with -EDEADLK and the owner + * released the lock while we were walking the + * pi chain. Let the waiter sort it out. + */ + ret = 0; + } + + if (unlikely(ret)) + remove_waiter(lock, waiter); + + raw_spin_unlock(&lock->wait_lock); + + debug_rt_mutex_print_deadlock(waiter); + + return ret; +} + +/** + * rt_mutex_next_owner - return the next owner of the lock + * + * @lock: the rt lock query + * + * Returns the next owner of the lock or NULL + * + * Caller has to serialize against other accessors to the lock + * itself. + * + * Special API call for PI-futex support + */ +struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock) +{ + if (!rt_mutex_has_waiters(lock)) + return NULL; + + return rt_mutex_top_waiter(lock)->task; +} + +/** + * rt_mutex_finish_proxy_lock() - Complete lock acquisition + * @lock: the rt_mutex we were woken on + * @to: the timeout, null if none. hrtimer should already have + * been started. + * @waiter: the pre-initialized rt_mutex_waiter + * @detect_deadlock: perform deadlock detection (1) or not (0) + * + * Complete the lock acquisition started our behalf by another thread. + * + * Returns: + * 0 - success + * <0 - error, one of -EINTR, -ETIMEDOUT, or -EDEADLK + * + * Special API call for PI-futex requeue support + */ +int rt_mutex_finish_proxy_lock(struct rt_mutex *lock, + struct hrtimer_sleeper *to, + struct rt_mutex_waiter *waiter, + int detect_deadlock) +{ + int ret; + + raw_spin_lock(&lock->wait_lock); + + set_current_state(TASK_INTERRUPTIBLE); + + ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter); + + set_current_state(TASK_RUNNING); + + if (unlikely(ret)) + remove_waiter(lock, waiter); + + /* + * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might + * have to fix that up. + */ + fixup_rt_mutex_waiters(lock); + + raw_spin_unlock(&lock->wait_lock); + + return ret; +} diff --git a/kernel/locking/rtmutex.h b/kernel/locking/rtmutex.h new file mode 100644 index 000000000000..a1a1dd06421d --- /dev/null +++ b/kernel/locking/rtmutex.h @@ -0,0 +1,26 @@ +/* + * 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 file contains macros used solely by rtmutex.c. + * Non-debug version. + */ + +#define rt_mutex_deadlock_check(l) (0) +#define rt_mutex_deadlock_account_lock(m, t) do { } while (0) +#define rt_mutex_deadlock_account_unlock(l) do { } while (0) +#define debug_rt_mutex_init_waiter(w) do { } while (0) +#define debug_rt_mutex_free_waiter(w) do { } while (0) +#define debug_rt_mutex_lock(l) do { } while (0) +#define debug_rt_mutex_proxy_lock(l,p) do { } while (0) +#define debug_rt_mutex_proxy_unlock(l) do { } while (0) +#define debug_rt_mutex_unlock(l) do { } while (0) +#define debug_rt_mutex_init(m, n) do { } while (0) +#define debug_rt_mutex_deadlock(d, a ,l) do { } while (0) +#define debug_rt_mutex_print_deadlock(w) do { } while (0) +#define debug_rt_mutex_detect_deadlock(w,d) (d) +#define debug_rt_mutex_reset_waiter(w) do { } while (0) diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h new file mode 100644 index 000000000000..53a66c85261b --- /dev/null +++ b/kernel/locking/rtmutex_common.h @@ -0,0 +1,126 @@ +/* + * 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 file contains the private data structure and API definitions. + */ + +#ifndef __KERNEL_RTMUTEX_COMMON_H +#define __KERNEL_RTMUTEX_COMMON_H + +#include <linux/rtmutex.h> + +/* + * The rtmutex in kernel tester is independent of rtmutex debugging. We + * call schedule_rt_mutex_test() instead of schedule() for the tasks which + * belong to the tester. That way we can delay the wakeup path of those + * threads to provoke lock stealing and testing of complex boosting scenarios. + */ +#ifdef CONFIG_RT_MUTEX_TESTER + +extern void schedule_rt_mutex_test(struct rt_mutex *lock); + +#define schedule_rt_mutex(_lock) \ + do { \ + if (!(current->flags & PF_MUTEX_TESTER)) \ + schedule(); \ + else \ + schedule_rt_mutex_test(_lock); \ + } while (0) + +#else +# define schedule_rt_mutex(_lock) schedule() +#endif + +/* + * This is the control structure for tasks blocked on a rt_mutex, + * which is allocated on the kernel stack on of the blocked task. + * + * @list_entry: pi node to enqueue into the mutex waiters list + * @pi_list_entry: pi node to enqueue into the mutex owner waiters list + * @task: task reference to the blocked task + */ +struct rt_mutex_waiter { + struct plist_node list_entry; + struct plist_node pi_list_entry; + struct task_struct *task; + struct rt_mutex *lock; +#ifdef CONFIG_DEBUG_RT_MUTEXES + unsigned long ip; + struct pid *deadlock_task_pid; + struct rt_mutex *deadlock_lock; +#endif +}; + +/* + * Various helpers to access the waiters-plist: + */ +static inline int rt_mutex_has_waiters(struct rt_mutex *lock) +{ + return !plist_head_empty(&lock->wait_list); +} + +static inline struct rt_mutex_waiter * +rt_mutex_top_waiter(struct rt_mutex *lock) +{ + struct rt_mutex_waiter *w; + + w = plist_first_entry(&lock->wait_list, struct rt_mutex_waiter, + list_entry); + BUG_ON(w->lock != lock); + + return w; +} + +static inline int task_has_pi_waiters(struct task_struct *p) +{ + return !plist_head_empty(&p->pi_waiters); +} + +static inline struct rt_mutex_waiter * +task_top_pi_waiter(struct task_struct *p) +{ + return plist_first_entry(&p->pi_waiters, struct rt_mutex_waiter, + pi_list_entry); +} + +/* + * lock->owner state tracking: + */ +#define RT_MUTEX_HAS_WAITERS 1UL +#define RT_MUTEX_OWNER_MASKALL 1UL + +static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock) +{ + return (struct task_struct *) + ((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL); +} + +/* + * PI-futex support (proxy locking functions, etc.): + */ +extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock); +extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock, + struct task_struct *proxy_owner); +extern void rt_mutex_proxy_unlock(struct rt_mutex *lock, + struct task_struct *proxy_owner); +extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock, + struct rt_mutex_waiter *waiter, + struct task_struct *task, + int detect_deadlock); +extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock, + struct hrtimer_sleeper *to, + struct rt_mutex_waiter *waiter, + int detect_deadlock); + +#ifdef CONFIG_DEBUG_RT_MUTEXES +# include "rtmutex-debug.h" +#else +# include "rtmutex.h" +#endif + +#endif |