Re: printk loglevel policy?

From: Jim Nelson (james4765_at_verizon.net)
Date: 01/03/05

  • Next message: Andrey Kislyuk: "oopses and panics on 2.6.9+K8T800" 
    Date:	Sun, 02 Jan 2005 23:44:03 -0500
To: "Randy.Dunlap" <rddunlap@osdl.org>

    Randy.Dunlap wrote:
    > Keith Owens wrote:
    >
    >> On Sun, 02 Jan 2005 13:41:34 -0800, "Randy.Dunlap" <rddunlap@osdl.org>
    >> wrote:
    >>
    >>> Jim Nelson wrote:
    >>>
    >>>> Or does printk() do some tracking that I didn't see as to where in
    >>>> the kernel the strings are coming from?
    >>>
    >>>
    >>> That kind of garbled output has been known to happen, but
    >>> the <console_sem> is supposed to prevent that (along with
    >>> zap_locks() in kernel/printk.c).
    >>
    >>
    >>
    >> Using multiple calls to printk to print a single line has always been
    >> subject to the possibility of interleaving on SMP. We just live with
    >> the risk. Printing a complete line in a single call to printk is
    >> protected by various locks. Print a line in multiple calls is not
    >> protected. If it bothers you that much, build up the line in a local
    >> buffer then call printk once.
    >
    >
    > True, I was thinking about the single line case, which I
    > have seen garbled/mixed in the past (on SMP). Hopefully
    > that one is fixed.
    >

    Okay, that answered my question. Is is frowned upon to use strncat/strcat in the
    kernel? I have yet to see any use of them outside of the definition in
    lib/string.c. It would seem to be faster (less potential contention for the
    printk locks).
    -
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  • Next message: Andrey Kislyuk: "oopses and panics on 2.6.9+K8T800"

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