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sched: add a few helpers to wake up tasks on the current cpu

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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>
This commit is contained in:
Andrei Vagin
2023-03-07 23:31:58 -08:00
committed by Kees Cook
parent ab83f455f0
commit 6f63904c8f
7 changed files with 33 additions and 14 deletions
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5
kernel/sched/wait.c
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@@ -161,6 +161,11 @@ int __wake_up(struct wait_queue_head *wq_head, unsigned int mode,
}
EXPORT_SYMBOL(__wake_up);
void __wake_up_on_current_cpu(struct wait_queue_head *wq_head, unsigned int mode, void *key)
{
__wake_up_common_lock(wq_head, mode, 1, WF_CURRENT_CPU, key);
}
/*
* Same as __wake_up but called with the spinlock in wait_queue_head_t held.
*/