diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/sched.h | 6 | ||||
| -rw-r--r-- | include/linux/spinlock.h | 14 |
2 files changed, 17 insertions, 3 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 923dd6ea4a0e..e9995eb5985c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1533,6 +1533,8 @@ static inline pid_t task_pgrp_nr(struct task_struct *tsk) * Test if a process is not yet dead (at most zombie state) * If pid_alive fails, then pointers within the task structure * can be stale and must not be dereferenced. + * + * Return: 1 if the process is alive. 0 otherwise. */ static inline int pid_alive(struct task_struct *p) { @@ -1544,6 +1546,8 @@ static inline int pid_alive(struct task_struct *p) * @tsk: Task structure to be checked. * * Check if a task structure is the first user space task the kernel created. + * + * Return: 1 if the task structure is init. 0 otherwise. */ static inline int is_global_init(struct task_struct *tsk) { @@ -1895,6 +1899,8 @@ extern struct task_struct *idle_task(int cpu); /** * is_idle_task - is the specified task an idle task? * @p: the task in question. + * + * Return: 1 if @p is an idle task. 0 otherwise. */ static inline bool is_idle_task(const struct task_struct *p) { diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 7d537ced949a..75f34949d9ab 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -117,9 +117,17 @@ do { \ #endif /*arch_spin_is_contended*/ #endif -/* The lock does not imply full memory barrier. */ -#ifndef ARCH_HAS_SMP_MB_AFTER_LOCK -static inline void smp_mb__after_lock(void) { smp_mb(); } +/* + * Despite its name it doesn't necessarily has to be a full barrier. + * It should only guarantee that a STORE before the critical section + * can not be reordered with a LOAD inside this section. + * spin_lock() is the one-way barrier, this LOAD can not escape out + * of the region. So the default implementation simply ensures that + * a STORE can not move into the critical section, smp_wmb() should + * serialize it with another STORE done by spin_lock(). + */ +#ifndef smp_mb__before_spinlock +#define smp_mb__before_spinlock() smp_wmb() #endif /** |