cvs commit: src/sys/sparc64/include bus.h bus_private.h iommuvar.h src/sys/sparc64/sparc64 bus_machdep.c iommu.c

[Thomas Moestl]

tmm         2003/07/10 16:27:35 PDT

  FreeBSD src repository

  Modified files:
    sys/sparc64/include  bus.h bus_private.h iommuvar.h 
    sys/sparc64/sparc64  bus_machdep.c iommu.c 
  Log:
  Lock down the IOMMU bus_dma implementation to make it safe to use
  without Giant held.
  
  A quick outline of the locking strategy:
  Since all IOMMUs are synchronized, there is a single lock, iommu_mtx,
  which protects the hardware registers (where needed) and the global and
  per-IOMMU software states. As soon as the IOMMUs are divorced, each struct
  iommu_state will have its own mutex (and the remaining global state
  will be moved into the struct).
  The dvma rman has its own internal mutex; the TSB slots may only be
  accessed by the owner of the corresponding resource, so neither needs
  extra protection.
  Since there is a second access path to maps via LRU queues, the consumer-
  provided locking is not sufficient; therefore, each map which is on a
  queue is additionally protected by iommu_mtx (in part, there is one
  member which only the map owner may access). Each map on a queue may
  be accessed and removed from or repositioned in a queue in any context as
  long as the lock is held; only the owner may insert a map.
  To reduce lock contention, some bus_dma functions remove the map from
  the queue temporarily (on behalf of the map owner) for some operations and
  reinsert it when they are done. Shorter operations and operations which are
  not done on behalf of the lock owner are completely covered by the lock.
  
  To facilitate the locking, reorganize the streaming buffer handling;
  while being there, fix an old oversight which would cause the streaming
  buffer to always be flushed, regardless of whether streaming was enabled
  in the TSB entry. The streaming buffer is still disabled for now, since
  there are a number of drivers which lack critical bus_dmamp_sync() calls.
  
  Additional testing by:  jake
  
  Revision  Changes    Path
  1.30      +3 -12     src/sys/sparc64/include/bus.h
  1.6       +20 -4     src/sys/sparc64/include/bus_private.h
  1.14      +32 -19    src/sys/sparc64/include/iommuvar.h
  1.33      +4 -4      src/sys/sparc64/sparc64/bus_machdep.c
  1.32      +207 -61   src/sys/sparc64/sparc64/iommu.c