Hi Boris, On Fri, 1 Feb 2008 19:29:09 +0100, Borislav Petkov wrote: > > > > end_that_request_last() is not called when __blk_end_reuqest() > > > > returns 1. Then, the issuer isn't waken up. > > > > So I think the BUG() or error messages should be there. > > > > > > you mean, end_that_request_last() isn't called when __end_that_request_first() > > > returns an error and this is the case only for fs and pc requests. > > > Otherwise it _is_ called, thus simulating somewhat the previous behavior. > > > However, we never BUG()'ged on residual byte counts before and > > > this driver has been in the kernel tree for ages, so what puzzles > > > me now is how is BUG()'ing here better than before and shouldn't we > > > simply issue a warning instead of killing the interrupt handler... > > > > The Jens' patch passes the residual byte counts to __blk_end_request(), > > so __end_that_reqeust_first() should never return 1 and we should never > > BUG() on the residual byte counts, unless inconsistency happens such as > > the size of remaining bios is bigger than the residual byte counts. > > yep. > > > So if __blk_end_request() returns 1 even with the Jens' patch, > > it means that the block layer or the driver really have a bug. > > And then, the request and the bios could leak or the issuer > > would wait forever because end_that_request_last() isn't called. > > > > The previous behavior might ignore such inconsistency and leak only > > the bios because it was calling end_that_request_last() anyway. > > I would like to BUG() in such cases personally, but I don't object > > strongly if you prefer not to BUG(). > > BUG() is definitely what we should do here to catch this case of sizeof(bios) > > rq->data_len. Putting a brown paper bag over the issue will never get it fixed > if it really leaks bios. Thanks for clarifying that. > > By the way, shouldn't we be doing a little branch prediction here: > > diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c > index 74c6087..bee05a3 100644 > --- a/drivers/ide/ide-cd.c > +++ b/drivers/ide/ide-cd.c > @@ -1722,7 +1722,7 @@ static ide_startstop_t cdrom_newpc_intr(ide_drive_t *drive) > */ > if ((stat & DRQ_STAT) == 0) { > spin_lock_irqsave(&ide_lock, flags); > - if (__blk_end_request(rq, 0, 0)) > + if (unlikely(__blk_end_request(rq, 0, rq->data_len))) > BUG(); > HWGROUP(drive)->rq = NULL; > spin_unlock_irqrestore(&ide_lock, flags); I think it's reasonable. Thanks, Kiyoshi Ueda - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html