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Oleg Nesterov
e73f8959af
Provide a simple mechanism that allows running code in the (nonatomic) context of the arbitrary task. The caller does task_work_add(task, task_work) and this task executes task_work->func() either from do_notify_resume() or from do_exit(). The callback can rely on PF_EXITING to detect the latter case. "struct task_work" can be embedded in another struct, still it has "void *data" to handle the most common/simple case. This allows us to kill the ->replacement_session_keyring hack, and potentially this can have more users. Performance-wise, this adds 2 "unlikely(!hlist_empty())" checks into tracehook_notify_resume() and do_exit(). But at the same time we can remove the "replacement_session_keyring != NULL" checks from arch/*/signal.c and exit_creds(). Note: task_work_add/task_work_run abuses ->pi_lock. This is only because this lock is already used by lookup_pi_state() to synchronize with do_exit() setting PF_EXITING. Fortunately the scope of this lock in task_work.c is really tiny, and the code is unlikely anyway. Signed-off-by: Oleg Nesterov <[email protected]> Acked-by: David Howells <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Richard Kuo <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Alexander Gordeev <[email protected]> Cc: Chris Zankel <[email protected]> Cc: David Smith <[email protected]> Cc: "Frank Ch. Eigler" <[email protected]> Cc: Geert Uytterhoeven <[email protected]> Cc: Larry Woodman <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Tejun Heo <[email protected]> Cc: Ingo Molnar <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Al Viro <[email protected]>
34 lines
748 B
C
34 lines
748 B
C
#ifndef _LINUX_TASK_WORK_H
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#define _LINUX_TASK_WORK_H
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#include <linux/list.h>
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#include <linux/sched.h>
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struct task_work;
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typedef void (*task_work_func_t)(struct task_work *);
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struct task_work {
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struct hlist_node hlist;
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task_work_func_t func;
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void *data;
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};
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static inline void
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init_task_work(struct task_work *twork, task_work_func_t func, void *data)
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{
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twork->func = func;
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twork->data = data;
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}
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int task_work_add(struct task_struct *task, struct task_work *twork, bool);
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struct task_work *task_work_cancel(struct task_struct *, task_work_func_t);
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void task_work_run(void);
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static inline void exit_task_work(struct task_struct *task)
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{
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if (unlikely(!hlist_empty(&task->task_works)))
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task_work_run();
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}
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#endif /* _LINUX_TASK_WORK_H */
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