---
- branch: MAIN
  date: Tue Dec 15 03:02:25 UTC 2009
  files:
  - new: '1.190'
    old: '1.189'
    path: src/sys/kern/subr_autoconf.c
    pathrev: src/sys/kern/subr_autoconf.c@1.190
    type: modified
  - new: '1.128'
    old: '1.127'
    path: src/sys/sys/device.h
    pathrev: src/sys/sys/device.h@1.128
    type: modified
  id: 20091215T030225Z.b4d7a2f220f3aa2696e520d2538b32832ffaa07b
  log: |
    Per rmind@'s suggestion, avoid an acquire/release-mutex dance by
    collecting garbage in two phases:  in the first stage, with
    alldevs_mtx held, gather all of the objects to be freed onto a
    list.  Drop alldevs_mtx, and in the second stage, free all the
    collected objects.

    Also per rmind@'s suggestion, remove KASSERT(!mutex_owned(&alldevs_mtx))
    throughout, it is not useful.

    Find a free unit number and allocate it for a new device_t atomically.
    Before, two threads would sometimes find the same free unit number
    and race to allocate it.  The loser panicked.  Now there is no
    race.

    In support of the changes above, extract some new subroutines that
    are private to this module: config_unit_nextfree(), config_unit_alloc(),
    config_devfree(), config_dump_garbage().

    Delete all of the #ifdef __BROKEN_CONFIG_UNIT_USAGE code.  Only
    the sun3 port still depends on __BROKEN_CONFIG_UNIT_USAGE, it's
    not hard for the port to do without, and port-sun3@ had fair warning
    that it was going away (>1 week, or a few years' warning, depending
    how far back you look!).
  module: src
  subject: 'CVS commit: src/sys'
  unixtime: '1260846145'
  user: dyoung