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author | Thomas Gleixner <tglx@linutronix.de> | 2017-03-09 12:06:41 +0100 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2017-03-09 12:06:41 +0100 |
commit | 920c634aff6cb66e7f352668521eb1313897e93c (patch) | |
tree | 0f2e2eb15756fdd93c8ea47f9080fc3c1abeeae6 /include/linux/sched/wake_q.h | |
parent | b28ace12661fbcfd90959c1e84ff5a85113a82a1 (diff) | |
parent | 4b9de5da7e120c7f02395da729f0ec77ce7a6044 (diff) |
Merge tag 'irq-fixes-4.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/urgent
Pull irqchip/irqdomain updates for 4.11-rc2 from Marc Zyngier
- irqchip/crossbar: Some type tidying up
- irqchip/gicv3-its: Workaround for a Qualcomm erratum
- irqdomain: Compile for for systems that don't use CONFIG_IRQ_DOMAIN
Fixed up minor conflict in the crossbar driver.
Diffstat (limited to 'include/linux/sched/wake_q.h')
-rw-r--r-- | include/linux/sched/wake_q.h | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/include/linux/sched/wake_q.h b/include/linux/sched/wake_q.h new file mode 100644 index 000000000000..d03d8a9047dc --- /dev/null +++ b/include/linux/sched/wake_q.h @@ -0,0 +1,53 @@ +#ifndef _LINUX_SCHED_WAKE_Q_H +#define _LINUX_SCHED_WAKE_Q_H + +/* + * Wake-queues are lists of tasks with a pending wakeup, whose + * callers have already marked the task as woken internally, + * and can thus carry on. A common use case is being able to + * do the wakeups once the corresponding user lock as been + * released. + * + * We hold reference to each task in the list across the wakeup, + * thus guaranteeing that the memory is still valid by the time + * the actual wakeups are performed in wake_up_q(). + * + * One per task suffices, because there's never a need for a task to be + * in two wake queues simultaneously; it is forbidden to abandon a task + * in a wake queue (a call to wake_up_q() _must_ follow), so if a task is + * already in a wake queue, the wakeup will happen soon and the second + * waker can just skip it. + * + * The DEFINE_WAKE_Q macro declares and initializes the list head. + * wake_up_q() does NOT reinitialize the list; it's expected to be + * called near the end of a function. Otherwise, the list can be + * re-initialized for later re-use by wake_q_init(). + * + * Note that this can cause spurious wakeups. schedule() callers + * must ensure the call is done inside a loop, confirming that the + * wakeup condition has in fact occurred. + */ + +#include <linux/sched.h> + +struct wake_q_head { + struct wake_q_node *first; + struct wake_q_node **lastp; +}; + +#define WAKE_Q_TAIL ((struct wake_q_node *) 0x01) + +#define DEFINE_WAKE_Q(name) \ + struct wake_q_head name = { WAKE_Q_TAIL, &name.first } + +static inline void wake_q_init(struct wake_q_head *head) +{ + head->first = WAKE_Q_TAIL; + head->lastp = &head->first; +} + +extern void wake_q_add(struct wake_q_head *head, + struct task_struct *task); +extern void wake_up_q(struct wake_q_head *head); + +#endif /* _LINUX_SCHED_WAKE_Q_H */ |