Re: [PATCH] scsi_debug: fix lba and data length calculation bugs

[FUJITA Tomonori <tomof@acm.org>]

On Wed, 26 Mar 2008 17:21:30 -0400
Douglas Gilbert <dougg@torque.net> wrote:

> FUJITA Tomonori wrote:
> > This fixes lba calculation bugs in scsi_debug (it might happen only
> > with over 1TB virtual devices).
> > 
> > This is against scsi-misc. scsi-fixes, 2.6.24, 2.6.23, ... probably
> > all the versions of scsi_debug have the same bugs too but I guess that
> > there are few people who play scsi_debug with over virtual 1TB devices
> > (though this can be cleanly applied to scsi-fixes).
> > 
> > Several LLDs have the own code to do the same calculation. It might be
> > nice to sweep up them?
> > 
> > =
> > From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
> > 
> > For example, `modprobe scsi_debug virtual_gb=1100` gives:
> > 
> > scsi7 : scsi_debug, version 1.81 [20070104], dev_size_mb=8, opts=0x0
> > scsi 7:0:0:0: Direct-Access     Linux    scsi_debug       0004 PQ: 0 ANSI: 5
> > sd 7:0:0:0: [sdc] 2306867200 512-byte hardware sectors (1181116 MB)
> > sd 7:0:0:0: [sdc] Write Protect is off
> > sd 7:0:0:0: [sdc] Mode Sense: 73 00 10 08
> > sd 7:0:0:0: [sdc] Write cache: enabled, read cache: enabled, supports DPO and FUA
> > sd 7:0:0:0: [sdc] 2306867200 512-byte hardware sectors (1181116 MB)
> > sd 7:0:0:0: [sdc] Write Protect is off
> > sd 7:0:0:0: [sdc] Mode Sense: 73 00 10 08
> > sd 7:0:0:0: [sdc] Write cache: enabled, read cache: enabled, supports DPO and FUA
> >  sdc: unknown partition table
> > sd 7:0:0:0: [sdc] Attached SCSI disk
> > sd 7:0:0:0: Attached scsi generic sg6 type 0
> > end_request: I/O error, dev sdc, sector 2306867072
> > Buffer I/O error on device sdc, logical block 288358384
> > end_request: I/O error, dev sdc, sector 2306867072
> > Buffer I/O error on device sdc, logical block 288358384
> > end_request: I/O error, dev sdc, sector 2306867192
> > 
> > (snip)
> > 
> > Note that this converts all the calculations (including the correct
> > calculations) for unification.
> > 
> > Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
> > Cc: Douglas Gilbert <dougg@torque.net>
> > Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
> > ---
> >  drivers/scsi/scsi_debug.c |   32 ++++++++++++++++++--------------
> >  1 files changed, 18 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> > index 4f4c5b7..46a136a 100644
> > --- a/drivers/scsi/scsi_debug.c
> > +++ b/drivers/scsi/scsi_debug.c
> > @@ -251,33 +251,37 @@ static struct bus_type pseudo_lld_bus;
> >  static void get_data_transfer_info(unsigned char *cmd,
> >  				   unsigned long long *lba, unsigned int *num)
> >  {
> > -	int i;
> > -
> >  	switch (*cmd) {
> >  	case WRITE_16:
> >  	case READ_16:
> > -		for (*lba = 0, i = 0; i < 8; ++i) {
> > -			if (i > 0)
> > -				*lba <<= 8;
> > -			*lba += cmd[2 + i];
> > -		}
> > -		*num = cmd[13] + (cmd[12] << 8) +
> > -			(cmd[11] << 16) + (cmd[10] << 24);
> > +		*lba = (u64)cmd[9] | (u64)cmd[8] << 8 |
> > +			(u64)cmd[7] << 16 | (u64)cmd[6] << 24 |
> > +			(u64)cmd[5] << 32 | (u64)cmd[4] << 40 |
> > +			(u64)cmd[3] << 48 | (u64)cmd[2] << 56;
> > +
> > +		*num = (u32)cmd[13] | (u32)cmd[12] << 8 | (u32)cmd[11] << 16 |
> > +			(u32)cmd[10] << 24;
> >  		break;
> >  	case WRITE_12:
> >  	case READ_12:
> > -		*lba = cmd[5] + (cmd[4] << 8) +	(cmd[3] << 16) + (cmd[2] << 24);
> > -		*num = cmd[9] + (cmd[8] << 8) +	(cmd[7] << 16) + (cmd[6] << 24);
> > +		*lba = (u32)cmd[5] | (u32)cmd[4] << 8 | (u32)cmd[3] << 16 |
> > +			(u32)cmd[2] << 24;
> > +
> > +		*num = (u32)cmd[9] | (u32)cmd[8] << 8 | (u32)cmd[7] << 16 |
> > +			(u32)cmd[6] << 24;
> >  		break;
> >  	case WRITE_10:
> >  	case READ_10:
> >  	case XDWRITEREAD_10:
> > -		*lba = cmd[5] + (cmd[4] << 8) +	(cmd[3] << 16) + (cmd[2] << 24);
> > -		*num = cmd[8] + (cmd[7] << 8);
> > +		*lba = (u32)cmd[5] | (u32)cmd[4] << 8 |	(u32)cmd[3] << 16 |
> > +			(u32)cmd[2] << 24;
> > +
> > +		*num = (u32)cmd[8] | (u32)cmd[7] << 8;
> >  		break;
> >  	case WRITE_6:
> >  	case READ_6:
> > -		*lba = cmd[3] + (cmd[2] << 8) + ((cmd[1] & 0x1f) << 16);
> > +		*lba = (u32)cmd[3] | (u32)cmd[2] << 8 |
> > +			(u32)(cmd[1] & 0x1f) << 16;
> >  		*num = (0 == cmd[4]) ? 256 : cmd[4];
> >  		break;
> >  	default:
> 
> Signed-off-by: Douglas Gilbert <dougg@torque.net>
> 
> 
> Can't actually see the "lba calculation bugs" but I'm happy
> to let Tomo do it his way.

Let me make things clear though we've already agreed offline.

Something like the following code doesn't work.

unsigned char *cmd;
unsigned long long *lba;

*lba = cmd[2] << 24;


So surely there are lba calculation bugs.