On Tue, 17 Jul 2001, Richard B. Johnson wrote:

> On Tue, 17 Jul 2001, Linus Torvalds wrote:
> 
> > In article <Pine.LNX.3.95.1010717103652.1430A-100000@chaos.analogic.com>,
> > Richard B. Johnson <root@chaos.analogic.com> wrote:
> > >
> > >    ticks = 1 * HZ;        /* For 1 second */
> > >    while((ticks = interruptible_sleep_on_timeout(&wqhead, ticks)) > 0)
> > >                  ;
> > 
> > Don't do this.
> > 
> > Imagine what happens if a signal comes in and wakes you up? The signal
> > will continue to be pending, which will make your "sleep loop" be a busy
> > loop as you can never go to sleep interruptibly with a pending signal.
> > 
> > In short: if you have to wait for a certain time or for a certain event,
> > you MUST NOT USE a interruptible sleep.
> > 
> > If it is ok to return early due to signals or similar (which is nice -
> > you can allow people to kill the process), then you use an interruptible
> > sleep, but then you mustn't have the above kind of loop.
> > 
> > 		Linus
> 
> Okay, then ../linux/drivers/net/8139too.c (line 2239) should be fixed
> because that's where it came from.
> 

I hate to answer my own questions, but the above may be correct if
the task doesn't stay in interruptible_sleep_on_timeout() if there
is a signal pending. If true, it will not loop forever because of
the test for signal_pending(current).


Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (799.53 BogoMips).

    I was going to compile a list of innovations that could be
    attributed to Microsoft. Once I realized that Ctrl-Alt-Del
    was handled in the BIOS, I found that there aren't any.


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