ide: remove broken/dangerous HDIO_[UNREGISTER,SCAN]_HWIF ioctls (take 3)

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: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

2 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/hdreg.h b/include/linux/hdreg.h
index e38e75967e7..c37e9241fae 100644
--- a/include/linux/hdreg.h
+++ b/include/linux/hdreg.h
@@ -422,9 +422,11 @@ struct hd_geometry {
 #define HDIO_SET_NOWERR		0x0325	/* change ignore-write-error flag */
 #define HDIO_SET_DMA		0x0326	/* change use-dma flag */
 #define HDIO_SET_PIO_MODE	0x0327	/* reconfig interface to new speed */
+#ifndef __KERNEL__
 #define HDIO_SCAN_HWIF		0x0328	/* register and (re)scan interface */
-#define HDIO_SET_NICE		0x0329	/* set nice flags */
 #define HDIO_UNREGISTER_HWIF	0x032a  /* unregister interface */
+#endif
+#define HDIO_SET_NICE		0x0329	/* set nice flags */
 #define HDIO_SET_WCACHE		0x032b	/* change write cache enable-disable */
 #define HDIO_SET_ACOUSTIC	0x032c	/* change acoustic behavior */
 #define HDIO_SET_BUSSTATE	0x032d	/* set the bus state of the hwif */
diff --git a/include/linux/ide.h b/include/linux/ide.h
index 67f83c60845..478ddf7e21d 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -1191,7 +1191,7 @@ static inline void ide_acpi_set_state(ide_hwif_t *hwif, int on) {}
 void ide_remove_port_from_hwgroup(ide_hwif_t *);
 extern int ide_hwif_request_regions(ide_hwif_t *hwif);
 extern void ide_hwif_release_regions(ide_hwif_t* hwif);
-void ide_unregister(unsigned int, int, int);
+void ide_unregister(unsigned int);
 
 void ide_register_region(struct gendisk *);
 void ide_unregister_region(struct gendisk *);