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    SubjectRe: PCI DMA to small buffers on cache-incoherent arch
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    >>>>> "Anton" == Anton Blanchard <anton@samba.org> writes:

    Anton> I just checked 2.5 and noticed the scsi code is _still_
    Anton> DMAing to the stack! Maybe it would be worth having a debug
    Anton> option for x86 where it uses vmalloc for kernel stack
    Anton> allocation :)

    Good catches, just a few comments on the patch.

    Anton> Anyway attached is a patch from Todd Inglett that I updated
    Anton> for 2.5.

    ===== drivers/scsi/scsi_scan.c 1.13 vs edited =====
    - /* Make sure we have something that is valid for DMA purposes */
    - scsi_result = ((!shpnt->unchecked_isa_dma)
    - ? &scsi_result0[0] : kmalloc(512, GFP_DMA));
    + scsi_result = kmalloc(512, GFP_DMA);

    I don't think you should always use GFP_DMA here... probably better to
    do:

    scsi_result = kmalloc(512,
    shpnt->unchecked_isa_dma ? GFP_DMA : GFP_ATOMIC);

    And similarly this:

    ===== drivers/scsi/sr_ioctl.c 1.13 vs edited =====
    + unsigned char *buffer = kmalloc(512, GFP_DMA);

    should probably use GFP_KERNEL (or possibly a check of
    unchecked_isa_dma as above, though this doesn't seem to be needed
    based on the existing code).

    Best,
    Roland
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