Re: [RFC] Driver writer's guide to sleeping

[Nish Aravamudan <nish.aravamudan@gmail.com>]

On 6/25/05, Denis Vlasenko <vda@ilport.com.ua> wrote:
> Hi folks,
> 
> I'm working on a Linux wireless driver.
> 
> I compiled a little guide for myself about waiting primitives.
> I would appreciate if you look thru it. Maybe I'm wrong somewhere.

<snip>
> schedule_timeout(timeout)
<snip>
> msleep(ms)
<snip>
> msleep_interruptible(ms)
<snip>

So, there are four cases in the schedule_timeout() family of sleeps,
based one what you would like to be woken up on:

Signals and Waitqueue events:
     set_current_state(TASK_INTERRUPTIBLE);
     schedule_timeout(some_time_in_jiffies);

Signals only:
     msleep_interruptible(some_time_in_msecs);

Waitqueue events only:
      set_current_state(TASK_UNINTERRUPTIBLE);
      schedule_timeout(some_time_in_jiffies);

Neither signals nor waitqueues:
      msleep(some_time_in_msecs);

Hopefully that clears some things up.

w.r.t to wait-queue event sleeping, you probably should also be aware
of the wait_event() family of macros.

Thanks,
Nish