On Monday 23 March 2009, Tejun Heo wrote:
> Hi,
>
> Bartlomiej Zolnierkiewicz wrote:
> >> It completes ide_floppy requests in the DMA handling block; however,
> >> those requests are gonna be completed again later in the regular
> >> completion path again. I think the above part can be simply dropped?
> >
> > I'm not sure I get it -- could you point me to the other completion path?
>
> static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
> {
> ....
> if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
> ....
> if (rc || (drive->media == ide_tape && (stat & ATA_ERR))) {
> if (drive->media == ide_floppy)
> printk(KERN_ERR "%s: DMA %s error\n",
> drive->name, rq_data_dir(pc->rq)
> ? "write" : "read");
> pc->flags |= PC_FLAG_DMA_ERROR;
> } else {
> pc->xferred = pc->req_xfer;
> if (drive->pc_update_buffers)
> drive->pc_update_buffers(drive, pc);
>
> if (drive->media == ide_floppy)
> 1: ide_complete_rq(drive, 0, blk_rq_bytes(rq));
> }
> debug_log("%s: DMA finished\n", drive->name);
> }
>
> /* No more interrupts */
> if ((stat & ATA_DRQ) == 0) {
> ...
> /* Command finished - Call the callback function */
> uptodate = drive->pc_callback(drive, dsc);
>
> if (uptodate == 0)
> drive->failed_pc = NULL;
>
> if (blk_special_request(rq)) {
> rq->errors = 0;
> 2: ide_complete_rq(drive, 0, blk_rq_bytes(rq));
> } else {
> unsigned int done;
>
> if (blk_fs_request(rq) == 0 && uptodate <= 0) {
> if (rq->errors == 0)
> rq->errors = -EIO;
> }
>
> if (drive->media == ide_tape)
> done = ide_rq_bytes(rq); /* FIXME */
> else
> done = blk_rq_bytes(rq);
>
> 3: ide_complete_rq(drive, uptodate ? 0 : -EIO, done);
> }
>
> return ide_stopped;
> }
> ...
> }
>
> #1 completely completes the request after which it shouldn't be
> accessed, but rq is accessed afterwards and #2 or #3 will be called on
> the rq again. Am I missing something?
Thanks for explanation.
[ IIRC "1:" was always there but in the form of partial completions loop
inside ->pc_update_buffers callback... ]
It seems like we really should remove "1:" but it would be best to retest
ide-floppy with this change. Borislav, could you add this to your queue?
Thanks,
Bart
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