On Tue, 29 Nov 2005, Jens Axboe wrote:
> > The hard problem is that sometimes devices return an ILLEGAL_REQUEST sense
> > key when they shouldn't. I posted an example a week or two ago; what
> > happened was the use_10_for_rw flag got turned off and from then on only
> > 6-byte commands were used (and of course the device failed to recognize
> > them).
> >
> > Clearly we need a mechanism for going the other way: when a 6-byte command
> > gets ILLEGAL_REQUEST sense, turn the use_10_for_xxx flag back on. The
> > difficulty is that this will cause an infinite retry loop if the device
> > doesn't like either form of the command.
> >
> > Is there a standard way to limit the number of retries for these cases in
> > scsi_io_completion? The code pathway involves getting rid of the
> > scsi_cmnd and keeping only the struct request, so I don't know where an
> > appropriate place would be to store the retry counter.
> >
> > Any ideas?
>
> How about just improving the check for correctly failed 10-byte command,
> so we only clear the flag for the right reason? I think your problem is
> likely due to the check being too relaxed right now.
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index ce9d73a..1f27827 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -884,7 +884,8 @@ void scsi_io_completion(struct scsi_cmnd
> * system where READ CAPACITY failed, we may have read
> * past the end of the disk.
> */
> - if (cmd->device->use_10_for_rw &&
> + if ((cmd->device->use_10_for_rw &&
> + sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
> (cmd->cmnd[0] == READ_10 ||
> cmd->cmnd[0] == WRITE_10)) {
> cmd->device->use_10_for_rw = 0;
This will not help. There's a log available at
http://www.cs.pdx.edu/~cklin/usb-error/0-original-kern.log
showing an example. Here's the relevant part:
Nov 19 00:31:13 rho kernel: usb-storage: Command READ_10 (10 bytes)
Nov 19 00:31:13 rho kernel: usb-storage: 28 00 02 54 29 78 00 00 08 00
Nov 19 00:31:13 rho kernel: usb-storage: Bulk Command S 0x43425355 T 0x8 L 4096 F 128 Trg 0 LUN 0 CL 12
Nov 19 00:31:13 rho kernel: usb-storage: usb_stor_bulk_transfer_buf: xfer 31 bytes
Nov 19 00:31:13 rho kernel: usb-storage: Status code 0; transferred 31/31
Nov 19 00:31:13 rho kernel: usb-storage: -- transfer complete
Nov 19 00:31:13 rho kernel: usb-storage: Bulk command transfer result=0
Nov 19 00:31:13 rho kernel: usb-storage: usb_stor_bulk_transfer_sglist: xfer 4096 bytes, 1 entries
Nov 19 00:31:13 rho kernel: usb-storage: Status code -32; transferred 4032/4096
Nov 19 00:31:13 rho kernel: usb-storage: clearing endpoint halt for pipe 0xc0020380
Nov 19 00:31:13 rho kernel: usb-storage: usb_stor_control_msg: rq=01 rqtype=02 value=0000 index=84 len=0
Nov 19 00:31:13 rho kernel: usb-storage: usb_stor_clear_halt: result = 0
Nov 19 00:31:13 rho kernel: usb-storage: Bulk data transfer result 0x2
Nov 19 00:31:13 rho kernel: usb-storage: Attempting to get CSW...
Nov 19 00:31:13 rho kernel: usb-storage: usb_stor_bulk_transfer_buf: xfer 13 bytes
Nov 19 00:31:13 rho kernel: usb-storage: Status code 0; transferred 13/13
Nov 19 00:31:13 rho kernel: usb-storage: -- transfer complete
Nov 19 00:31:13 rho kernel: usb-storage: Bulk status result = 0
Nov 19 00:31:13 rho kernel: usb-storage: Bulk Status S 0x53425355 T 0x8 R 64 Stat 0x1
Nov 19 00:31:13 rho kernel: usb-storage: -- transport indicates command failure
Nov 19 00:31:13 rho kernel: usb-storage: -- unexpectedly short transfer
Nov 19 00:31:13 rho kernel: usb-storage: Issuing auto-REQUEST_SENSE
Nov 19 00:31:13 rho kernel: usb-storage: Bulk Command S 0x43425355 T 0x9 L 18 F 128 Trg 0 LUN 0 CL 12
Nov 19 00:31:13 rho kernel: usb-storage: usb_stor_bulk_transfer_buf: xfer 31 bytes
Nov 19 00:31:13 rho kernel: usb-storage: Status code 0; transferred 31/31
Nov 19 00:31:13 rho kernel: usb-storage: -- transfer complete
Nov 19 00:31:13 rho kernel: usb-storage: Bulk command transfer result=0
Nov 19 00:31:13 rho kernel: usb-storage: usb_stor_bulk_transfer_buf: xfer 18 bytes
Nov 19 00:31:13 rho kernel: usb-storage: Status code 0; transferred 18/18
Nov 19 00:31:13 rho kernel: usb-storage: -- transfer complete
Nov 19 00:31:13 rho kernel: usb-storage: Bulk data transfer result 0x0
Nov 19 00:31:13 rho kernel: usb-storage: Attempting to get CSW...
Nov 19 00:31:13 rho kernel: usb-storage: usb_stor_bulk_transfer_buf: xfer 13 bytes
Nov 19 00:31:13 rho kernel: usb-storage: Status code 0; transferred 13/13
Nov 19 00:31:13 rho kernel: usb-storage: -- transfer complete
Nov 19 00:31:13 rho kernel: usb-storage: Bulk status result = 0
Nov 19 00:31:13 rho kernel: usb-storage: Bulk Status S 0x53425355 T 0x9 R 0 Stat 0x0
Nov 19 00:31:13 rho kernel: usb-storage: -- Result from auto-sense is 0
Nov 19 00:31:13 rho kernel: usb-storage: -- code: 0x70, key: 0x5, ASC: 0x20, ASCQ: 0x0
In this case the drive transmitted all but the last 64 bytes of a
4096-byte READ(10), and the sense data was exactly what you want to test
for.
Alan Stern
-
: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
