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6f63904c8f
Add complete_on_current_cpu, wake_up_poll_on_current_cpu helpers to wake up tasks on the current CPU. These two helpers are useful when the task needs to make a synchronous context switch to another task. In this context, synchronous means it wakes up the target task and falls asleep right after that. One example of such workloads is seccomp user notifies. This mechanism allows the supervisor process handles system calls on behalf of a target process. While the supervisor is handling an intercepted system call, the target process will be blocked in the kernel, waiting for a response to come back. On-CPU context switches are much faster than regular ones. Signed-off-by: Andrei Vagin <avagin@google.com> Acked-by: "Peter Zijlstra (Intel)" <peterz@infradead.org> Link: https://lore.kernel.org/r/20230308073201.3102738-4-avagin@google.com Signed-off-by: Kees Cook <keescook@chromium.org>
122 lines
4.1 KiB
C
122 lines
4.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_COMPLETION_H
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#define __LINUX_COMPLETION_H
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/*
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* (C) Copyright 2001 Linus Torvalds
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*
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* Atomic wait-for-completion handler data structures.
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* See kernel/sched/completion.c for details.
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*/
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#include <linux/swait.h>
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/*
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* struct completion - structure used to maintain state for a "completion"
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*
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* This is the opaque structure used to maintain the state for a "completion".
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* Completions currently use a FIFO to queue threads that have to wait for
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* the "completion" event.
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*
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* See also: complete(), wait_for_completion() (and friends _timeout,
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* _interruptible, _interruptible_timeout, and _killable), init_completion(),
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* reinit_completion(), and macros DECLARE_COMPLETION(),
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* DECLARE_COMPLETION_ONSTACK().
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*/
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struct completion {
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unsigned int done;
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struct swait_queue_head wait;
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};
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#define init_completion_map(x, m) init_completion(x)
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static inline void complete_acquire(struct completion *x) {}
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static inline void complete_release(struct completion *x) {}
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#define COMPLETION_INITIALIZER(work) \
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{ 0, __SWAIT_QUEUE_HEAD_INITIALIZER((work).wait) }
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#define COMPLETION_INITIALIZER_ONSTACK_MAP(work, map) \
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(*({ init_completion_map(&(work), &(map)); &(work); }))
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#define COMPLETION_INITIALIZER_ONSTACK(work) \
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(*({ init_completion(&work); &work; }))
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/**
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* DECLARE_COMPLETION - declare and initialize a completion structure
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* @work: identifier for the completion structure
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*
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* This macro declares and initializes a completion structure. Generally used
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* for static declarations. You should use the _ONSTACK variant for automatic
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* variables.
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*/
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#define DECLARE_COMPLETION(work) \
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struct completion work = COMPLETION_INITIALIZER(work)
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/*
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* Lockdep needs to run a non-constant initializer for on-stack
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* completions - so we use the _ONSTACK() variant for those that
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* are on the kernel stack:
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*/
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/**
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* DECLARE_COMPLETION_ONSTACK - declare and initialize a completion structure
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* @work: identifier for the completion structure
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*
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* This macro declares and initializes a completion structure on the kernel
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* stack.
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*/
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#ifdef CONFIG_LOCKDEP
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# define DECLARE_COMPLETION_ONSTACK(work) \
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struct completion work = COMPLETION_INITIALIZER_ONSTACK(work)
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# define DECLARE_COMPLETION_ONSTACK_MAP(work, map) \
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struct completion work = COMPLETION_INITIALIZER_ONSTACK_MAP(work, map)
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#else
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# define DECLARE_COMPLETION_ONSTACK(work) DECLARE_COMPLETION(work)
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# define DECLARE_COMPLETION_ONSTACK_MAP(work, map) DECLARE_COMPLETION(work)
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#endif
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/**
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* init_completion - Initialize a dynamically allocated completion
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* @x: pointer to completion structure that is to be initialized
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*
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* This inline function will initialize a dynamically created completion
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* structure.
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*/
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static inline void init_completion(struct completion *x)
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{
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x->done = 0;
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init_swait_queue_head(&x->wait);
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}
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/**
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* reinit_completion - reinitialize a completion structure
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* @x: pointer to completion structure that is to be reinitialized
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*
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* This inline function should be used to reinitialize a completion structure so it can
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* be reused. This is especially important after complete_all() is used.
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*/
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static inline void reinit_completion(struct completion *x)
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{
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x->done = 0;
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}
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extern void wait_for_completion(struct completion *);
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extern void wait_for_completion_io(struct completion *);
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extern int wait_for_completion_interruptible(struct completion *x);
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extern int wait_for_completion_killable(struct completion *x);
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extern int wait_for_completion_state(struct completion *x, unsigned int state);
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extern unsigned long wait_for_completion_timeout(struct completion *x,
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unsigned long timeout);
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extern unsigned long wait_for_completion_io_timeout(struct completion *x,
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unsigned long timeout);
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extern long wait_for_completion_interruptible_timeout(
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struct completion *x, unsigned long timeout);
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extern long wait_for_completion_killable_timeout(
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struct completion *x, unsigned long timeout);
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extern bool try_wait_for_completion(struct completion *x);
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extern bool completion_done(struct completion *x);
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extern void complete(struct completion *);
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extern void complete_on_current_cpu(struct completion *x);
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extern void complete_all(struct completion *);
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#endif
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