Re: [ANNOUNCE] Kernel Janitor's TODO list

From: Timur Tabi (ttabi@interactivesi.com)
Date: Mon Jan 29 2001 - 12:01:31 EST

  • Next message: John Levon: "Re: [ANNOUNCE] Kernel Janitor's TODO list"

    This is driving me crazy! There is absolutely no documentation anywhere that
    tells you when to use or not use sleep_on or spin_lock_whatever or any of these
    calls. How is anyone supposed to know how to use these functions?! The post I
    quoted below just proves that a lot of people think they know but apparently
    don't! In fact, I predict that an argument between the two posters and a few
    others will soon ensue over who is right.

    What makes it more frustrating is that some people on this list talk as if
    things things are common knowledge. I've been following this mailing list for
    months, and until today I had no idea sleep_on was bad. All the documentation
    I've read to date freely uses sleep_on in the sample code. In fact, I still
    don't even know WHY it's bad. Not only that, but what am I supposed to use
    instead?

    This is what I find most frustrating about Linux. If I were a Windows driver
    programmer, I could walk into any bookstore and pick up any of a dozen books
    that explains everything, leaving no room for doubt.

    ** Reply to message from Roman Zippel <zippel@fh-brandenburg.de> on Sun, 28 Jan
    2001 19:51:57 +0100 (MET)

    > Hi,
    >
    > On Sun, 28 Jan 2001, Manfred Spraul wrote:
    >
    > > And one more point for the Janitor's list:
    > > Get rid of superflous irqsave()/irqrestore()'s - in 90% of the cases
    > > either spin_lock_irq() or spin_lock() is sufficient. That's both faster
    > > and better readable.
    > >
    > > spin_lock_irq(): you know that the function is called with enabled
    > > interrupts.
    > > spin_lock(): can be used in hardware interrupt handlers when only one
    > > hardware interrupt uses that spinlocks (most hardware drivers), or when
    > > all hardware interrupt handler set the SA_INTERRUPT flag (e.g. rtc and
    > > timer interrupt)
    >
    > This is not a bug and only helps to make drivers nonportable. Please,
    > don't do this.
    >
    > bye, Roman
    >
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    -- 
Timur Tabi - ttabi@interactivesi.com
Interactive Silicon - http://www.interactivesi.com

    When replying to a mailing-list message, please direct the reply to the mailing list only.  Don't send another copy to me.

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