linux-kernel - Re: [PATCH] ide-cd: handle fragmented packet commands gracefully

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Date:	Mon, 22 Jun 2009 11:50:22 +0200
From:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
To:	Borislav Petkov <petkovbb@...glemail.com>,
	David Miller <davem@...emloft.net>
Cc:	linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ide-cd: handle fragmented packet commands gracefully

On Sunday 21 June 2009 10:55:27 Borislav Petkov wrote:
> There are some devices in the wild that clear the DRQ bit during the
> last word of a packet command and therefore could use a "second chance"
> for that last word of data to be xferred instead of simply failing the
> request. Do that by attempting to suck in those last bytes in PIO mode.
> 
> In addition, the ATA_ERR bit has to be cleared for we cannot be sure the
> data is valid otherwise.
> 
> See http://bugzilla.kernel.org/show_bug.cgi?id=13399 for details.
> 
> Signed-off-by: Borislav Petkov <petkovbb@...il.com>

Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>

> ---
>  drivers/ide/ide-cd.c |   14 ++++++++++++--
>  1 files changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
> index 4a19686..8d3f7d0 100644
> --- a/drivers/ide/ide-cd.c
> +++ b/drivers/ide/ide-cd.c
> @@ -592,9 +592,19 @@ static ide_startstop_t cdrom_newpc_intr(ide_drive_t *drive)
>  			}
>  		} else if (!blk_pc_request(rq)) {
>  			ide_cd_request_sense_fixup(drive, cmd);
> -			/* complain if we still have data left to transfer */
> +
>  			uptodate = cmd->nleft ? 0 : 1;
> -			if (uptodate == 0)
> +
> +			/*
> +			 * suck out the remaining bytes from the drive in an
> +			 * attempt to complete the data xfer. (see BZ#13399)
> +			 */
> +			if (!(stat & ATA_ERR) && !uptodate && thislen) {
> +				ide_pio_bytes(drive, cmd, write, thislen);
> +				uptodate = cmd->nleft ? 0 : 1;
> +			}
> +
> +			if (!uptodate)
>  				rq->cmd_flags |= REQ_FAILED;
>  		}
>  		goto out_end;
--
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