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    SubjectRe: [PATCH 00/10] IOCHK interface for I/O error handling/detecting
    On Thu, Jun 09, 2005 at 09:39:11PM +0900, Hidetoshi Seto wrote:
    > Previously I had post two prototypes to LKML:
    > 1) readX_check() interface
    > Added new kin of basic readX(), which returns its result of
    > I/O. But, it would not make sense that device driver have to
    > check and react after each of I/Os.
    > 2) clear/read_pci_errors() interface
    > Added new pair-interface to sandwich I/Os. It makes sense that
    > device driver can adjust the number of checking I/Os and can
    > react all of them at once. However, this was not generalized,
    > so I thought that more expandable design would be required.
    > Today's patch is 3rd one - iochk_clear/read() interface.
    > - This also adds pair-interface, but not to sandwich only readX().
    > Depends on platform, starting with ioreadX(), inX(), writeX()
    > if possible... and so on could be target of error checking.

    It makes sense to sandwich other kinds of device accesses. I don't
    think the previous clear/read_pci_errors() interface was intended *only*
    to sandwich readX().

    > - Additionally adds special token - abstract "iocookie" structure
    > to control/identifies/manage I/Os, by passing it to OS.
    > Actual type of "iocookie" could be arch-specific. Device drivers
    > could use the iocookie structure without knowing its detail.

    I'm not sure we need this. Surely it can be deduced from the pci_dev or
    struct device?

    > Expected usage(sample) is:
    > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    > #include <linux/pci.h>
    > #include <asm/io.h>
    > int sample_read_with_iochk(struct pci_dev *dev, u32 *buf, int words)
    > {
    > unsigned long ofs = pci_resource_start(dev, 0) + DATA_OFFSET;
    > int i;
    > /* Create magical cookie on the stack */
    > iocookie cookie;
    > /* Critical section start */
    > iochk_clear(&dev, &cookie);
    > {
    > /* Get the whole packet of data */
    > for (i = 0; i < words; i++)
    > *buf++ = ioread32(dev, ofs);

    You do know that ioread32() doesn't take a pci_dev, right? I hope you
    weren't counting on that for the rest of your implementation.

    > }
    > /* Critical section end. Did we have any trouble? */
    > if ( iochk_read(&cookie) ) return -1;
    > /* OK, all system go. */
    > return 0;
    > }

    "Next the statesmen will invent cheap lies, putting the blame upon
    the nation that is attacked, and every man will be glad of those
    conscience-soothing falsities, and will diligently study them, and refuse
    to examine any refutations of them; and thus he will by and by convince
    himself that the war is just, and will thank God for the better sleep
    he enjoys after this process of grotesque self-deception." -- Mark Twain
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