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cvs commit: src/sys/dev/netif/vr if_vr.c if_vrreg.h

From: Sepherosa Ziehau <sephe@xxxxxxxxxxxxxxxxxxxxxxx>
Date: Mon, 21 Nov 2005 05:20:29 -0800 (PST)

sephe       2005/11/21 05:20:29 PST

DragonFly src repository

  Modified files:
    sys/dev/netif/vr     if_vr.c if_vrreg.h 
  There are two possible causes which will make vr(4) stall:
  in vr_start(), if vr_encap() fails:
  1) vr_start() will set IFF_OACTIVE.  If the packet causing vr_encap() to fail
     is the only packet pending to be downloaded to device, vr(4) will stall,
     * No more packets can be transfered, because IFF_OACTIVE is turned on
     * Except for vr_{init, stop}(), vr_txeoc() is the only function that can
       turn off IFF_OACTIVE.  It is triggered by "frame download completing"
       interrupt.  But this kind of interrupt will not be generated here, since
       there are no other packets pending to be downloaded.
  2) vr_start() will skip TX head and tail pointer updating, which leaks all
     previous successfully encapsulated TX chains.
  Following fixes are applied:
  - Allocate chunk of memory in vr_attch() to reduce the failure chance of
    vr_encap().  This will also reduce the load of mbuf allocation system
  - Use indexes instead of pointers for TX chain processing.  This can save us
    some spaces in every vr_chain
  - Update Tx head and tail indexes when there are successfully encapsultaed
    packets pending to be downloaded to device, even if vr_encap() fails for
    some packets
  - Cache TX buffer and next TX descriptor's physical address in vr_chain, since
    these addresses are fixed during the life time of vr(4)
  Other stuffs:
  - Use M_ZERO flag in memory allocation instead of calling bzero() later
  - Remove (char *) cast in bzero()
  - Minor style changes
  Reported-by: corecode
  With-helps-form: joerg
  Reviewed-by: joerg, submit@
  Revision  Changes    Path
  1.38      +122 -84   src/sys/dev/netif/vr/if_vr.c
  1.8       +13 -7     src/sys/dev/netif/vr/if_vrreg.h


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