cvs commit: src/sys/dev/if_ndis if_ndis.c if_ndisvar.h

[Coleman Kane]

cokane      2008-06-11 13:40:15 UTC

  FreeBSD src repository

  Modified files:
    sys/dev/if_ndis      if_ndis.c if_ndisvar.h 
  Log:
  SVN rev 179723 on 2008-06-11 13:40:15Z by cokane
  
  Convert ndis_spinlock to ndis_mtx and start using the sleepable
  mtx interface for NDIS_LOCK/UNLOCK. This should result in less
  CPU utilization on behalf of the ndis driver. Additionally, this
  commit also fixes a potential LOR in the ndis_tick code, by
  not locking inside the ndis_tick function, but instead delegating
  that work to the helpers called through IoQueueWorkItem. The
  way that this is currently set up for NDIS prevents us from
  simply implementing a callout_init_mtx mechanism.
  
  However, the helper functions that handle the various timeout
  cases implement fine-grained locking using the spinlocks provided
  by the NDIS-compat layer, and using the mtx that is added with
  this commit. This leaves the following ndis_softc members operated
  on in ndis_tick in an unlocked context:
  
    * ndis_hang_timer - Only modified outside of ndis_tick once, before
                        the first callout_reset to schedule ndis_tick
    * ifp->if_oerrors - Only incremented in two places, which should be
                        an atomic op
    * ndis_tx_timer   - Assigned to 5 (when guaranteed to be 0) or 0
                        (in txeof), to indicate to ndis_tick what to
                        do. This is the only member of which I was
                        suspicious for needing the NDIS_LOCK here. My
                        testing (and another's) have been fine so far.
    * ndis_stat_callout - Only uses a simple set of callout routines,
                          callout_reset only called by ndis_tick after
                          the initial reset, and then callout_drain is
                          used exactly once in shutdown code.
  
  The benefit is that ndis_tick doesn't acquire NDIS_LOCK unless one of
  the timeout conditions is flagged, and it still obeys the locking
  order semantics that are dictated by the NDIS layer at the moment. I
  have been investigating a more thorough s/spinlock/mtx/ of the NDIS
  layer, but the simplest naive approach (replace KeAcquireSpinLock
  with an mtx implementation) has anti-succeeded for me so far. This
  is a good first step though.
  
  Tested by:      onemda at gmail.com
  Reviewed by:    current@, jhb, thompsa
  Proposed by:    jhb
  
  Revision  Changes    Path
  1.142     +2 -3      src/sys/dev/if_ndis/if_ndis.c
  1.33      +3 -5      src/sys/dev/if_ndis/if_ndisvar.h