• Bartlomiej Zolnierkiewicz's avatar
    ide: remove broken/dangerous HDIO_[UNREGISTER,SCAN]_HWIF ioctls (take 3) · 93de00fd
    Bartlomiej Zolnierkiewicz authored
    hdparm explicitely marks HDIO_[UNREGISTER,SCAN]_HWIF ioctls as DANGEROUS
    and given the number of bugs we can assume that there are no real users:
    
    * DMA has no chance of working because DMA resources are released by
      ide_unregister() and they are never allocated again.
    
    * Since ide_init_hwif_ports() is used for ->io_ports[] setup the ioctls
      don't work for almost all hosts with "non-standard" (== non ISA-like)
      layout of IDE taskfile registers (there is a lot of such host drivers).
    
    * ide_port_init_devices() is not called when probing IDE devices so:
      - drive->autotune is never set and IDE host/devices are not programmed
        for the correct PIO/DMA transfer modes (=> possible data corruption)
      - host specific I/O 32-bit and IRQ unmasking settings are not applied
        (=> possible data corruption)
      - host specific ->port_init_devs method is not called (=> no luck with
        ht6560b, qd65xx and opti621 host drivers)
    
    * ->rw_disk method is not preserved (=> no HPT3xxN chipsets support).
    
    * ->serialized flag is not preserved (=> possible data corruption when
       using icside, aec62xx (ATP850UF chipset), cmd640, cs5530, hpt366
       (HPT3xxN chipsets), rz1000, sc1200, dtc2278 and ht6560b host drivers).
    
    * ->ack_intr method is not preserved (=> needed by ide-cris, buddha,
      gayle and macide host drivers).
    
    * ->sata_scr[] and sata_misc[] is cleared by ide_unregister() and it
      isn't initialized again (SiI3112 support needs them).
    
    * To issue an ioctl() there need to be at least one IDE device present
      in the system.
    
    * ->cable_detect method is not preserved + it is not called when probing
      IDE devices so cable detection is broken (however since DMA support is
      also broken it doesn't really matter ;-).
    
    * Some objects which may have already been freed in ide_unregister()
      are restored by ide_hwif_restore() (i.e. ->hwgroup).
    
    * ide_register_hw() may unregister unrelated IDE ports if free ide_hwifs[]
      slot cannot be found.
    
    * When IDE host drivers are modular unregistered port may be re-used by
      different host driver that owned it first causing subtle bugs.
    
    Since we now have a proper warm-plug support remove these ioctls,
    then remove no longer needed:
    - ide_register_hw() and ide_hwif_restore() functions
    - 'init_default' and 'restore' arguments of ide_unregister()
    - zeroeing of hwif->{dma,extra}_* fields in ide_unregister()
    
    As an added bonus IDE core code size shrinks by ~3kB (x86-32).
    
    v2:
    * fix ide_unregister() arguments in cleanup_module() (Andrew Morton).
    
    v3:
    * fix ide_unregister() arguments in palm_bk3710.c.
    Acked-by: default avatarSergei Shtylyov <sshtylyov@ru.mvista.com>
    Signed-off-by: default avatarBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
    93de00fd
hdreg.h 24.4 KB