how can we wake up some process which is scheduled?

[Dave Hylands]

Hi loody,

On Tue, Dec 13, 2011 at 12:44 AM, loody <miloody at gmail.com> wrote:

> hi all:
> There is a kernel API, "schedule_timeout_interruptible".
> since it has the name interruptible, who and how can we interrupt this
> task?
> suppose A use schedule_timeout_interruptible for 20s period and B
> found something and he want to wake up A within this 20s period.
>

You send the task a signal. The API for doing this has a rather unfortunate
name, and is called kill from user-space.

>From kernel space, you can use kill_pid_info, or kill_proc_info.
kill_pid_info is what's called to send SIGALARM when an itimer expires.

Although using signals in kernel space is fairly rare, it's typically a
user-space to kernel-space thing, not a kernel-space to kernel-space thing.

In kernel space, I would generally use something like a timed semaphore
(down_timeout).

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com
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