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Date: Fri, 16 Jan 2004 11:51:52 -0500 (EST)
From: "Richard B. Johnson" <root@chaos.analogic.com>
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To: Linux kernel <linux-kernel@vger.kernel.org>
Subject: timing code in 2.6.1
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Some drivers are being re-written for 2.6++. The following
construct seems to work for "waiting for an event" in
the kernel modules.

        // No locks are being held
        tim = jiffies + EVENT_TIMEOUT;
        while(!event() && time_before(jiffies, tim))
            schedule_timeout(0);

Is there anything wrong?
Do I have to execute "set_current_state(TASK_INTERRUPTIBLE)" before?
Do I have to execute "set_current_state(TASK_RUNNING)" after?

I don't want to have to change this again so I really need to
know. For instance, if I execute "set_current_state(TASK_INTERRUPTIBLE)"
in version 2.4.24, it didn't hurt anything. In 2.6.1, there are
conditions where schedule_timeout(0) doesn't return if another
task is spinning "while(1) ; ". This is NotGood(tm).

Cheers,
Dick Johnson
Penguin : Linux version 2.4.24 on an i686 machine (797.90 BogoMips).
            Note 96.31% of all statistics are fiction.