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Uninitialized field and duplicated function in kauai.c ?


Reading the arch/macppc/dev/kauai.c driver I found something strange
regarding the 'sc_dmacmd' field for the buffer of DBDMA commands:

It's defined as a pointer in kauai_softc (line numbers are for rev. 1.24):

    61  struct kauai_softc {
    68          dbdma_command_t *sc_dmacmd;
    74  };

 However, such filed is nowhere initialized to point to a valid
allocated buffer. kauai_attach() just tests if the buffer is 16-byte
aligned as required by DBDMA, but as it's not initialized, it points
to address 0 so the error should never be triggered:

   106  void
   107  kauai_attach(device_t parent, device_t self, void *aux)
   108  {
   119  #ifdef DIAGNOSTIC
   120          if ((vaddr_t)sc->sc_dmacmd & 0x0f) {
   121                  aprint_error(": bad dbdma alignment\n");
   122                  return;
   123          }
   124  #endif

Then this uninitialized pointer is used by kauai_dma_init() :

   286  int
   287  kauai_dma_init(void *v, int channel, int drive, void *databuf,
   288          size_t datalen, int flags)
   289  {
   290          struct kauai_softc *sc = v;
   291          dbdma_command_t *cmdp = sc->sc_dmacmd;
   310                          DBDMA_BUILD(cmdp, cmd, 0, rest, vtophys(va),

It looks like it was meant to be defined as an array in the softc or
allocated with the dbdma_alloc() function (which is what wdc_obio.c
does), which in addition also makes sure the buffer is 16-byte

There is also a private function defined in kauai.c, getnodebypci(),
which is line-for-line identical to the pcidev_to_ofdev() function
defined in arch/powerpc/oea/ofw_autoconf.c (in 4.0 it's on

     83  static int getnodebypci(pci_chipset_tag_t, pcitag_t);
   126          node = getnodebypci(pa->pa_pc, pa->pa_tag);
   357  /*
   358   * Find OF-device corresponding to the PCI device.
   359   */
   360  int
   361  getnodebypci(pci_chipset_tag_t pc, pcitag_t tag)



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