locks to be cleaned up?
In the common case, at do_exit() time, there is no list registered, so
-the cost of robust futexes is just a simple current->robust_list != NULL
+the cost of robust futexes is just a current->futex.robust_list != NULL
comparison. If the thread has registered a list, then normally the list
is empty. If the thread/process crashed or terminated in some incorrect
way then the list might be non-empty: in this case the kernel carefully
size_t __user *len_ptr);
List registration is very fast: the pointer is simply stored in
-current->robust_list. [Note that in the future, if robust futexes become
-widespread, we could extend sys_clone() to register a robust-list head
-for new threads, without the need of another syscall.]
+current->futex.robust_list. [Note that in the future, if robust futexes
+become widespread, we could extend sys_clone() to register a robust-list
+head for new threads, without the need of another syscall.]
So there is virtually zero overhead for tasks not using robust futexes,
and even for robust futex users, there is only one extra syscall per
static inline void futex_init_task(struct task_struct *tsk)
{
- tsk->robust_list = NULL;
-#ifdef CONFIG_COMPAT
- tsk->compat_robust_list = NULL;
-#endif
- INIT_LIST_HEAD(&tsk->pi_state_list);
- tsk->pi_state_cache = NULL;
- tsk->futex_state = FUTEX_STATE_OK;
- mutex_init(&tsk->futex_exit_mutex);
+ memset(&tsk->futex, 0, sizeof(tsk->futex));
+ INIT_LIST_HEAD(&tsk->futex.pi_state_list);
+ tsk->futex.state = FUTEX_STATE_OK;
+ mutex_init(&tsk->futex.exit_mutex);
}
void futex_exit_recursive(struct task_struct *tsk);
--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_FUTEX_TYPES_H
+#define _LINUX_FUTEX_TYPES_H
+
+#ifdef CONFIG_FUTEX
+#include <linux/mutex_types.h>
+#include <linux/types.h>
+
+struct compat_robust_list_head;
+struct futex_pi_state;
+struct robust_list_head;
+
+/**
+ * struct futex_sched_data - Futex related per task data
+ * @robust_list: User space registered robust list pointer
+ * @compat_robust_list: User space registered robust list pointer for compat tasks
+ * @pi_state_list: List head for Priority Inheritance (PI) state management
+ * @pi_state_cache: Pointer to cache one PI state object per task
+ * @exit_mutex: Mutex for serializing exit
+ * @state: Futex handling state to handle exit races correctly
+ */
+struct futex_sched_data {
+ struct robust_list_head __user *robust_list;
+#ifdef CONFIG_COMPAT
+ struct compat_robust_list_head __user *compat_robust_list;
+#endif
+ struct list_head pi_state_list;
+ struct futex_pi_state *pi_state_cache;
+ struct mutex exit_mutex;
+ unsigned int state;
+};
+#else
+struct futex_sched_data { };
+#endif /* !CONFIG_FUTEX */
+
+#endif /* _LINUX_FUTEX_TYPES_H */
#include <linux/cpumask_types.h>
#include <linux/cache.h>
+#include <linux/futex_types.h>
#include <linux/irqflags_types.h>
#include <linux/smp_types.h>
#include <linux/pid_types.h>
struct capture_control;
struct cfs_rq;
struct fs_struct;
-struct futex_pi_state;
struct io_context;
struct io_uring_task;
struct mempolicy;
struct pipe_inode_info;
struct rcu_node;
struct reclaim_state;
-struct robust_list_head;
struct root_domain;
struct rq;
struct sched_attr;
u32 closid;
u32 rmid;
#endif
-#ifdef CONFIG_FUTEX
- struct robust_list_head __user *robust_list;
-#ifdef CONFIG_COMPAT
- struct compat_robust_list_head __user *compat_robust_list;
-#endif
- struct list_head pi_state_list;
- struct futex_pi_state *pi_state_cache;
- struct mutex futex_exit_mutex;
- unsigned int futex_state;
-#endif
+
+ struct futex_sched_data futex;
+
#ifdef CONFIG_PERF_EVENTS
u8 perf_recursion[PERF_NR_CONTEXTS];
struct perf_event_context *perf_event_ctxp;
proc_exit_connector(tsk);
mpol_put_task_policy(tsk);
#ifdef CONFIG_FUTEX
- if (unlikely(current->pi_state_cache))
- kfree(current->pi_state_cache);
+ if (unlikely(current->futex.pi_state_cache))
+ kfree(current->futex.pi_state_cache);
#endif
/*
* Make sure we are holding no locks:
* "But they come in a choice of three flavours!"
*/
#include <linux/compat.h>
-#include <linux/jhash.h>
-#include <linux/pagemap.h>
#include <linux/debugfs.h>
-#include <linux/plist.h>
+#include <linux/fault-inject.h>
#include <linux/gfp.h>
-#include <linux/vmalloc.h>
+#include <linux/jhash.h>
#include <linux/memblock.h>
-#include <linux/fault-inject.h>
-#include <linux/slab.h>
-#include <linux/prctl.h>
#include <linux/mempolicy.h>
#include <linux/mmap_lock.h>
+#include <linux/pagemap.h>
+#include <linux/plist.h>
+#include <linux/prctl.h>
+#include <linux/rseq.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
#include "futex.h"
#include "../locking/rtmutex_common.h"
if (WARN_ON_ONCE(ret == -EBUSY && !exiting))
return;
- mutex_lock(&exiting->futex_exit_mutex);
+ mutex_lock(&exiting->futex.exit_mutex);
/*
* No point in doing state checking here. If the waiter got here
* while the task was in exec()->exec_futex_release() then it can
* already. Highly unlikely and not a problem. Just one more round
* through the futex maze.
*/
- mutex_unlock(&exiting->futex_exit_mutex);
+ mutex_unlock(&exiting->futex.exit_mutex);
put_task_struct(exiting);
}
*
* In both cases the following conditions are met:
*
- * 1) task->robust_list->list_op_pending != NULL
+ * 1) task->futex.robust_list->list_op_pending != NULL
* @pending_op == true
* 2) The owner part of user space futex value == 0
* 3) Regular futex: @pi == false
*/
static void exit_robust_list(struct task_struct *curr)
{
- struct robust_list_head __user *head = curr->robust_list;
+ struct robust_list_head __user *head = curr->futex.robust_list;
struct robust_list __user *entry, *next_entry, *pending;
unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
unsigned int next_pi;
*/
static void compat_exit_robust_list(struct task_struct *curr)
{
- struct compat_robust_list_head __user *head = curr->compat_robust_list;
+ struct compat_robust_list_head __user *head = curr->futex.compat_robust_list;
struct robust_list __user *entry, *next_entry, *pending;
unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
unsigned int next_pi;
*/
static void exit_pi_state_list(struct task_struct *curr)
{
- struct list_head *next, *head = &curr->pi_state_list;
+ struct list_head *next, *head = &curr->futex.pi_state_list;
struct futex_pi_state *pi_state;
union futex_key key = FUTEX_KEY_INIT;
static void futex_cleanup(struct task_struct *tsk)
{
- if (unlikely(tsk->robust_list)) {
+ if (unlikely(tsk->futex.robust_list)) {
exit_robust_list(tsk);
- tsk->robust_list = NULL;
+ tsk->futex.robust_list = NULL;
}
#ifdef CONFIG_COMPAT
- if (unlikely(tsk->compat_robust_list)) {
+ if (unlikely(tsk->futex.compat_robust_list)) {
compat_exit_robust_list(tsk);
- tsk->compat_robust_list = NULL;
+ tsk->futex.compat_robust_list = NULL;
}
#endif
- if (unlikely(!list_empty(&tsk->pi_state_list)))
+ if (unlikely(!list_empty(&tsk->futex.pi_state_list)))
exit_pi_state_list(tsk);
}
void futex_exit_recursive(struct task_struct *tsk)
{
/* If the state is FUTEX_STATE_EXITING then futex_exit_mutex is held */
- if (tsk->futex_state == FUTEX_STATE_EXITING) {
- __assume_ctx_lock(&tsk->futex_exit_mutex);
- mutex_unlock(&tsk->futex_exit_mutex);
+ if (tsk->futex.state == FUTEX_STATE_EXITING) {
+ __assume_ctx_lock(&tsk->futex.exit_mutex);
+ mutex_unlock(&tsk->futex.exit_mutex);
}
- tsk->futex_state = FUTEX_STATE_DEAD;
+ tsk->futex.state = FUTEX_STATE_DEAD;
}
static void futex_cleanup_begin(struct task_struct *tsk)
- __acquires(&tsk->futex_exit_mutex)
+ __acquires(&tsk->futex.exit_mutex)
{
/*
* Prevent various race issues against a concurrent incoming waiter
* including live locks by forcing the waiter to block on
- * tsk->futex_exit_mutex when it observes FUTEX_STATE_EXITING in
+ * tsk->futex.exit_mutex when it observes FUTEX_STATE_EXITING in
* attach_to_pi_owner().
*/
- mutex_lock(&tsk->futex_exit_mutex);
+ mutex_lock(&tsk->futex.exit_mutex);
/*
* Switch the state to FUTEX_STATE_EXITING under tsk->pi_lock.
* be observed in exit_pi_state_list().
*/
raw_spin_lock_irq(&tsk->pi_lock);
- tsk->futex_state = FUTEX_STATE_EXITING;
+ tsk->futex.state = FUTEX_STATE_EXITING;
raw_spin_unlock_irq(&tsk->pi_lock);
}
static void futex_cleanup_end(struct task_struct *tsk, int state)
- __releases(&tsk->futex_exit_mutex)
+ __releases(&tsk->futex.exit_mutex)
{
/*
* Lockless store. The only side effect is that an observer might
* take another loop until it becomes visible.
*/
- tsk->futex_state = state;
+ tsk->futex.state = state;
/*
* Drop the exit protection. This unblocks waiters which observed
* FUTEX_STATE_EXITING to reevaluate the state.
*/
- mutex_unlock(&tsk->futex_exit_mutex);
+ mutex_unlock(&tsk->futex.exit_mutex);
}
void futex_exec_release(struct task_struct *tsk)
{
struct futex_pi_state *pi_state;
- if (likely(current->pi_state_cache))
+ if (likely(current->futex.pi_state_cache))
return 0;
pi_state = kzalloc_obj(*pi_state);
refcount_set(&pi_state->refcount, 1);
pi_state->key = FUTEX_KEY_INIT;
- current->pi_state_cache = pi_state;
+ current->futex.pi_state_cache = pi_state;
return 0;
}
static struct futex_pi_state *alloc_pi_state(void)
{
- struct futex_pi_state *pi_state = current->pi_state_cache;
+ struct futex_pi_state *pi_state = current->futex.pi_state_cache;
WARN_ON(!pi_state);
- current->pi_state_cache = NULL;
+ current->futex.pi_state_cache = NULL;
return pi_state;
}
if (new_owner) {
raw_spin_lock(&new_owner->pi_lock);
WARN_ON(!list_empty(&pi_state->list));
- list_add(&pi_state->list, &new_owner->pi_state_list);
+ list_add(&pi_state->list, &new_owner->futex.pi_state_list);
pi_state->owner = new_owner;
raw_spin_unlock(&new_owner->pi_lock);
}
raw_spin_unlock_irqrestore(&pi_state->pi_mutex.wait_lock, flags);
}
- if (current->pi_state_cache) {
+ if (current->futex.pi_state_cache) {
kfree(pi_state);
} else {
/*
*/
pi_state->owner = NULL;
refcount_set(&pi_state->refcount, 1);
- current->pi_state_cache = pi_state;
+ current->futex.pi_state_cache = pi_state;
}
}
*
* p->pi_lock:
*
- * p->pi_state_list -> pi_state->list, relation
+ * p->futex.pi_state_list -> pi_state->list, relation
* pi_mutex->owner -> pi_state->owner, relation
*
* pi_state->refcount:
* If the futex exit state is not yet FUTEX_STATE_DEAD, tell the
* caller that the alleged owner is busy.
*/
- if (tsk && tsk->futex_state != FUTEX_STATE_DEAD)
+ if (tsk && tsk->futex.state != FUTEX_STATE_DEAD)
return -EBUSY;
/*
* *uaddr = 0xC0000000; tsk = get_task(PID);
* } if (!tsk->flags & PF_EXITING) {
* ... attach();
- * tsk->futex_state = } else {
- * FUTEX_STATE_DEAD; if (tsk->futex_state !=
+ * tsk->futex.state = } else {
+ * FUTEX_STATE_DEAD; if (tsk->futex.state !=
* FUTEX_STATE_DEAD)
* return -EAGAIN;
* return -ESRCH; <--- FAIL
pi_state->key = *key;
WARN_ON(!list_empty(&pi_state->list));
- list_add(&pi_state->list, &p->pi_state_list);
+ list_add(&pi_state->list, &p->futex.pi_state_list);
/*
* Assignment without holding pi_state->pi_mutex.wait_lock is safe
* because there is no concurrency as the object is not published yet.
* in futex_exit_release(), we do this protected by p->pi_lock:
*/
raw_spin_lock_irq(&p->pi_lock);
- if (unlikely(p->futex_state != FUTEX_STATE_OK)) {
+ if (unlikely(p->futex.state != FUTEX_STATE_OK)) {
/*
* The task is on the way out. When the futex state is
* FUTEX_STATE_DEAD, we know that the task has finished
* @head: pointer to the list-head
* @len: length of the list-head, as userspace expects
*/
-SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head,
- size_t, len)
+SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head, size_t, len)
{
- /*
- * The kernel knows only one size for now:
- */
+ /* The kernel knows only one size for now. */
if (unlikely(len != sizeof(*head)))
return -EINVAL;
- current->robust_list = head;
-
+ current->futex.robust_list = head;
return 0;
}
{
#ifdef CONFIG_COMPAT
if (compat)
- return p->compat_robust_list;
+ return p->futex.compat_robust_list;
#endif
- return p->robust_list;
+ return p->futex.robust_list;
}
static void __user *futex_get_robust_list_common(int pid, bool compat)
}
#ifdef CONFIG_COMPAT
-COMPAT_SYSCALL_DEFINE2(set_robust_list,
- struct compat_robust_list_head __user *, head,
- compat_size_t, len)
+COMPAT_SYSCALL_DEFINE2(set_robust_list, struct compat_robust_list_head __user *, head,
+ compat_size_t, len)
{
if (unlikely(len != sizeof(*head)))
return -EINVAL;
- current->compat_robust_list = head;
-
+ current->futex.compat_robust_list = head;
return 0;
}
return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3);
}
#endif /* CONFIG_COMPAT_32BIT_TIME */
-
projects / thirdparty / linux.git / commitdiff
