Re: 2.6.19-rc3 system freezes when ripping with cdparanoia at ioctl(SG_IO)

[Douglas Gilbert <dougg@torque.net>]

Christoph Hellwig wrote:
> On Fri, Nov 10, 2006 at 12:08:15PM -0800, Luben Tuikov wrote:
>> P.S. I'd love to see SG_DXFER_TO_FROM_DEV completely ripped out
>> of sg.c, for obvious reasons.  Can you not duplicate the resid "fix"
>> it provides into "FROM_DEV" -- do apps really rely on it?
> 
> At the beginning of this thread it was mentioned cdparanio uses it.
> But in general we can't just rip out userland interfaces, we pretend
> to have a stable userspace abi (and except for the big sysfs mess that
> actually comes very close to the truth).
> 
> What we should do is to document very well what SG_DXFER_TO_FROM_DEV
> is doing and that odd name that's been chosen for it.  I'll prepare
> a patch for that.

Christoph,
It is documented and has been from day one. See scsi/sg.h
and http://sg.torque.net/sg/p/sg_v3_ho.html

Naming it is a challenge and at the time there
were no bidirectional transfers to/from a device
to worry about.

A more appropriate but impractical name might be:
SG_DXFER_TO_KERNEL_BUFFER_THEN_READ_FROM_DEV_VIA_KERNEL_BUFFER


Doug Gilbert

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