2011-03-19 19:53:59

by Roel Kluin

Subject: [PATCH] osst: wrong index used in inner loop

Index i was already used in the outer loop.

Signed-off-by: Roel Kluin <[email protected]>
---
drivers/scsi/osst.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)

I'm not sure if this is the right fix, maybe a break or return
is missing?

diff --git a/drivers/scsi/osst.c b/drivers/scsi/osst.c
index 521e218..d6d6d89 100644
--- a/drivers/scsi/osst.c
+++ b/drivers/scsi/osst.c
@@ -4702,8 +4702,9 @@ static int __os_scsi_tape_open(struct inode * inode, struct file * filp)
STp->partition = STp->new_partition = 0;
if (STp->can_partitions)
STp->nbr_partitions = 1; /* This guess will be updated later if necessary */
- for (i=0; i < ST_NBR_PARTITIONS; i++) {
- STps = &(STp->ps[i]);
+ int j;
+ for (j=0; j < ST_NBR_PARTITIONS; j++) {
+ STps = &(STp->ps[j]);
STps->rw = ST_IDLE;
STps->eof = ST_NOEOF;
STps->at_sm = 0;

2011-03-21 01:03:57

by FUJITA Tomonori

Subject: Re: [PATCH] osst: wrong index used in inner loop

On Sat, 19 Mar 2011 20:53:53 +0100
roel <[email protected]> wrote:

> Index i was already used in the outer loop.
>
> Signed-off-by: Roel Kluin <[email protected]>
> ---
> drivers/scsi/osst.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> I'm not sure if this is the right fix, maybe a break or return
> is missing?

What are you trying to fix with this patch?


> diff --git a/drivers/scsi/osst.c b/drivers/scsi/osst.c
> index 521e218..d6d6d89 100644
> --- a/drivers/scsi/osst.c
> +++ b/drivers/scsi/osst.c
> @@ -4702,8 +4702,9 @@ static int __os_scsi_tape_open(struct inode * inode, struct file * filp)
> STp->partition = STp->new_partition = 0;
> if (STp->can_partitions)
> STp->nbr_partitions = 1; /* This guess will be updated later if necessary */
> - for (i=0; i < ST_NBR_PARTITIONS; i++) {
> - STps = &(STp->ps[i]);
> + int j;
> + for (j=0; j < ST_NBR_PARTITIONS; j++) {
> + STps = &(STp->ps[j]);
> STps->rw = ST_IDLE;
> STps->eof = ST_NOEOF;
> STps->at_sm = 0;
> --
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2011-03-21 11:00:14

by Roel Kluin

Subject: Re: [PATCH] osst: wrong index used in inner loop

On 21-03-11 02:02, FUJITA Tomonori wrote:
> On Sat, 19 Mar 2011 20:53:53 +0100
> roel <[email protected]> wrote:
>
>> Index i was already used in the outer loop.
>>
>> Signed-off-by: Roel Kluin <[email protected]>
>> ---
>> drivers/scsi/osst.c | 5 +++--
>> 1 files changed, 3 insertions(+), 2 deletions(-)
>>
>> I'm not sure if this is the right fix, maybe a break or return
>> is missing?
>
> What are you trying to fix with this patch?

`i' is used as an index in both the outer loop at 4689 and the
inner loop at 4705.

if the UNIT_ATTENTION branch is taken `i' is overwritten after the
loop at 4705 and becomes ST_NBR_PARTITIONS + 1, i.e. 5.

So the loop at 4689 may not loop ten times when the UNIT_ATTENTION
branch is taken. It may loop 5 times or more than ten or hot spin,
dependent how often the UNIT_ATTENTION branch is taken. I'm not
familiar with this driver, but it looked buggy to me.

Roel