cvs commit: src/sys/dev/sound/pcm sound.c

[Ariff Abdullah]

ariff       2006-03-31 10:36:36 UTC

  FreeBSD src repository

  Modified files:
    sys/dev/sound/pcm    sound.c 
  Log:
  MEGA Fixes / Cleanup
  --------------------
  
  - Seal the fate of long standing memory leak (4 years, 7 months) during
    pcm_unregister(). While destroying cdevs, scan / detect possible
    children and free its SLIST placeholder properly.
  - Optimize channel allocation / numbering even further. Do brute cyclic
    checking only if the channel numbering screwed.
  - Mega vchan create/destroy cleanup:
    o Implement pcm_setvchans() so everybody can use it freely instead
      of implementing their own, be it through sysctl or channel auto
      allocation.
    o Increase vchan creation/destruction resiliency:
      + it's possible to increase/decrease total vchans even during
        busy playback/recording. Busy channel will be left alone, untouched.
        Abusive test sample:
        # play whatever...
        #
           while : ; do
             sysctl hw.snd.pcm0.vchans=1
             sysctl hw.snd.pcm0.vchans=10
             sysctl hw.snd.pcm0.vchans=100
             sysctl hw.snd.pcm0.vchans=200
           done
        # Play something else, leave above loop running frantically.
      + Seal another 4 years old bug where it is possible to destroy (virtual)
        channel even when its cdevs being referenced by other process.
        The "First Come First Served" nature of dsp_clone() is the main
        culprit of this issue, and usually manifest itself as dangling
        channel <-> process association. Ensure that all of its cdevs
        are free from being referenced before destroying it (through
        ORPHAN_CDEVT() macross).
  
  All these fixes (including previous fixes) will be MFCed, later.
  
  Revision  Changes    Path
  1.103     +239 -300  src/sys/dev/sound/pcm/sound.c