Re: [PATCH] IDE PIO write Fix #2

[Martin Dalecki]

Uz.ytkownik tomita napisa?:
> Hi.
> This patch solves problem (for me)
> "kernel stops without message at heavy usage of IDE HDD".
> But, "hda: lost interrupt" message appears, instead. 
> My BOX has both IDE and SCSI HDD.
> This message appears at accessing SCSI HDD by another
> task, during IDE heavy accsess.
> I guess, IDE driver has "critical section" needing "cli"
> (and so on).
> Any suggestions ?
> 
> --- linux-2.5.15/drivers/ide/ide-taskfile.c.orig	Fri May 10 11:49:35 2002
> +++ linux-2.5.15/drivers/ide/ide-taskfile.c	Tue May 14 10:40:43 2002
> @@ -606,7 +606,7 @@
>  		if (!ide_end_request(drive, rq, 1))
>  			return ide_stopped;
>  
> -	if ((rq->current_nr_sectors==1) ^ (stat & DRQ_STAT)) {
> +	if ((rq->nr_sectors == 1) ^ ((stat & DRQ_STAT) != 0)) {
>  		pBuf = ide_map_rq(rq, &flags);
>  		DTF("write: %p, rq->current_nr_sectors: %d\n", pBuf, (int) rq->current_nr_sectors);

Hmm. There is something else that smells in the above, since the XOR operator
doesn't seem to be proper. Why shouldn't we get DRQ_STAT at all on short
request? Could you perhaps just try to replace it with an OR?

Thinking about the kernel hang and SCSI - I would have to ask whatever there
is really interrupt sharing between IDE and SCSI. If the hangs happen due to
the usage of ide-scsi then I already know what's going - ide-scsi doesn't
do proper locking on command submission to the ATA layer.