Re: dev_lock() question

From: John Baldwin (jhb_at_FreeBSD.org)
Date: 09/30/05

  • Next message: John Baldwin: "Re: A smarter mergemaster" 
    To: freebsd-hackers@freebsd.org
Date: Fri, 30 Sep 2005 08:59:59 -0400

    On Thursday 29 September 2005 03:36 pm, Poul-Henning Kamp wrote:
    > In message <200509291455.59914.jhb@FreeBSD.org>, John Baldwin writes:
    > >On Thursday 29 September 2005 02:14 pm, Poul-Henning Kamp wrote:
    > >> In message <200509291408.18098.jhb@FreeBSD.org>, John Baldwin writes:
    > >> >Actually, you would think that it could be initialized either via an
    > >> > early SYSINIT() or in the init_mutexes() function in kern_mutex.c and
    > >> > thus not need the early check and avoid penalizing dev_lock().
    > >> >
    > >> >phk, how early his dev_lock needed?
    > >>
    > >> Far too early due to console madness (in syscons I belive).
    > >
    > >So would mutex_init() work?
    >
    > Havn't tried. It basically has to work right before the copyright
    > is printed.

    Actually, mutexes won't work until after mutex_init() anyway, so it had better
    work. :) I'll try it out. Patch is below for reference:

    --- //depot/vendor/freebsd/src/sys/kern/kern_conf.c 2005/09/19 20:01:08
    +++ //depot/projects/smpng/sys/kern/kern_conf.c 2005/09/30 12:57:36
    @@ -57,8 +57,7 @@
     void
     dev_lock(void)
     {
    - if (!mtx_initialized(&devmtx))
    - mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
    +
             mtx_lock(&devmtx);
     }
     
    --- //depot/vendor/freebsd/src/sys/kern/kern_mutex.c 2005/09/02 20:25:20
    +++ //depot/projects/smpng/sys/kern/kern_mutex.c 2005/09/30 12:57:36
    @@ -900,5 +935,6 @@
             mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
             mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
             mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
    + mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
             mtx_lock(&Giant);
     } 

    -- 
John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org
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