Re: [KJ] do all schedule_timeout() calls need to set state first?

[Nishanth Aravamudan <nacc@us.ibm.com>]

On 19.03.2007 [14:00:53 -0400], Robert P. J. Day wrote:
> 
>   based on what i've been reading, all calls to schedule_timeout()
> *must* first set the current process state to either
> TASK_INTERRUPTIBLE or TASK_UNINTERRUPTIBLE, is that correct?

Yes, but note that setting it directly before is not always necessary,
in particular when used with wait-queues. But, take a look at the
comment heading schedule_timeout():

 * Make the current task sleep until @timeout jiffies have elapsed. The
 * routine will return immediately unless the current task state has
 * been set (see set_current_state()).

>   since i was once again perusing the source tree and noticed the
> following in drivers/hwmon/ams/ams-i2c.c (line 93):
> 
>         while (remaining) {
>                 result = ams_i2c_read(AMS_COMMAND);
>                 if (result = 0 || result & 0x80)
>                         return 0;
> 
>                 remaining = schedule_timeout(remaining);
>         }
> 
> it certainly *seems* that the state isn't being set here.  is that an
> error?  just curious.

Yes, it is. That is why we have schedule_timeout_interruptible() and
schedule_timeout_uninterruptible().

Thanks,
Nish

-- 
Nishanth Aravamudan <nacc@us.ibm.com>
IBM Linux Technology Center
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