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    SubjectRe: [PATCH]: Fix old SCSI adapter crashes with CD-ROM (take 2)
    James Bottomley wrote:
    > On Tue, 2007-05-08 at 18:14 +0200, Jens Axboe wrote:
    >> On Tue, May 08 2007, Alan Cox wrote:
    >>> The CD-ROM layer doesn't bounce requests for old ISA controllers (and
    >>> nor should it). However they get injected into the SCSI layer via
    >>> sr_ioctl which also doesn't bounce them and SCSI then passes the buffer
    >>> along to a device with unchecked_isa_dma set which either panics or
    >>> truncates the buffer to 24bits.
    >>>
    >>> According to Jens the right long term fix is for the CD layer to route
    >>> the requests differently but in the mean time this has been tested by a
    >>> victim and verified to sort the problem out. For the other 99.9% of users
    >>> it's a no-op and doesn't bounce data.
    >>>
    >>> Signed-off-by: Alan Cox <alan@redhat.com>
    >> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
    >>
    >> Christoph passed me his patch to get rid of ->generic_packet() in the
    >> cdrom layer, so the work is almost complete. This patch is fine as a
    >> work-around until that gets merged, though.
    >
    > Actually, I think the new scsi request infrastructure should be doing
    > the bouncing (rather than have it done in each problem path we
    > discover).
    >
    > Mike Christie tells me we're missing bouncing by accident in the
    > scsi_execute path (but not the scsi_execute_async path). He says this
    > is the fix he proposed:
    >
    > http://marc.info/?l=linux-scsi&m=115981479822790&w=2
    >

    Hey Jens and James, one thing I forgot to mention is that I could not
    remember if I needed an extra bio_get in there. I thought I did not
    because the caller is not touching the bio after the bio_endio calls
    like is done with the blk/bio_map_user path. But I did that patch so
    long ago I do not remember now.
    -
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