Re: [PATCH 15/18] ide: remove broken/dangerous HDIO_[UNREGISTER,SCAN]_HWIF ioctls
From: Sergei Shtylyov <hidden>
Date: 2008-03-27 17:37:48
Also in:
linuxppc-dev, lkml
Bartlomiej Zolnierkiewicz wrote:
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).
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Acked-by: Sergei Shtylyov <redacted>
quoted hunk ↗ jump to hunk
Index: b/drivers/ide/ide-pnp.c ===================================================================--- a/drivers/ide/ide-pnp.c +++ b/drivers/ide/ide-pnp.c
[...]
quoted hunk ↗ jump to hunk
@@ -655,52 +530,6 @@ void ide_init_port_hw(ide_hwif_t *hwif, } EXPORT_SYMBOL_GPL(ide_init_port_hw); -/** - * ide_register_hw - register IDE interface - * @hw: hardware registers - * @quirkproc: quirkproc function - * @hwifp: pointer to returned hwif - * - * Register an IDE interface, specifying exactly the registers etc. - * - * Returns -1 on error. - */ - -static int ide_register_hw(hw_regs_t *hw, void (*quirkproc)(ide_drive_t *), - ide_hwif_t **hwifp) -{ - int index, retry = 1; - ide_hwif_t *hwif; - u8 idx[4] = { 0xff, 0xff, 0xff, 0xff }; - - do { - hwif = ide_find_port(hw->io_ports[IDE_DATA_OFFSET]); - index = hwif->index; - if (hwif) - goto found;
Hm, I remember there was a patch that fixed the above bug where hwif is
dereferenced before being checked for NULL, I wonder how come it was lost?
WBR, Sergei