Oh God, please indent code examples, and if your email client strips white
space, change your email client.
On Fri, 21 Oct 2005, Yitzchak Eidus wrote:
> first i am very sorry if it isnt the place to ask questions like this
> but i didnt know where else to ask ( i tryed irc channels and i was
> send from there to this list )
> anyway:
> does this following code look buggy? :
[ Indention added ]
> DECLARE_WAITQUEUE ( wait , current );
> add_wait_queue ( q , &wait );
> while ( !condition ) {
> set_current_stat ( TASK_INTERRUPTABLE ); i
> if ( signal_pending ( current ) )
> /* handle signal */
I assume that the signal_pending is the if result and not the schedule.
Since there was no indentation I couldn't tell.
> schedule ( );
/* Moved brace down added */
}
> set_current_state ( TASK_RUNNING );
> remove_wait_queue ( q , &wait );
Before I go to your questions, I'll first answer that this _is_ buggy
code. If the condition is checked and you are woken up between the
while (!condition) and the set_current_state, then you will end up
sleeping forever or until someone sends you a signal.
> first:doesnt in the way from checking the !condition to
> set_current_state the condition can be changed no?
Yes, and then put it again after schedule.
>
> second:why not putting the schedule ( ); right after the
> set_current_state ( ) , what the point in checking the if (
> signal_pending ( ) first, if the proccess doesnt started to sleep yet?
Yes, I would put the signal_pending check after the schedule (as most of
the kernel does this).
> third: in the cleaning in the way from putting the set_current_state (
> TASK_RUNNING ) into remove_wait_queue , cant the queue wait list ( q )
> wake up again the wait procsess?
Yeah, so? There's no harm in that, except for an extra cpu cycles that
are done to wake it up. That, I wouldn't change.
> ( thnks for the help , please if it can be done answer quickly i am
> tanker in the idf and need to come back to the army soon , ( no
> internet there... ) )
BTW, this is not an IRC, we use normal capitalization and normal spelling
(when we know how to spell a word ;-). So the next time you send to the
list, send it as if you were writing a serious letter, or you may just be
ignored. (as you might have been if I didn't respond).
-- Steve
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