Re: [PATCH v2 21/24] scsi: pm8001: Fix pm8001_task_exec()

[John Garry <john.garry@huawei.com>]

On 11/02/2022 07:37, Damien Le Moal wrote:

Hi Damien,

> The n_elem local variable in pm8001_task_exec() is initialized to 0 and
> changed set to the number of DMA scatter elements for a needed for a
> task command only for ATA commands and for SAS commands that have a
> non-zero number of sg segments. n_elem is never initialized to 0 for SAS

Do you mean re-initialized?

I thought the current code was ok, as we init n_elem = 0 and we only 
ever loop once. Am I missing something?

Thanks,
john

> commands that do not no sg segments, potentially leading to an incorrect
> value of n_elem being used for a task. Add the missing 0 initialization.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> ---
>   drivers/scsi/pm8001/pm8001_sas.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/pm8001/pm8001_sas.c b/drivers/scsi/pm8001/pm8001_sas.c
> index 7b749da82a61..8cd7e7837f41 100644
> --- a/drivers/scsi/pm8001/pm8001_sas.c
> +++ b/drivers/scsi/pm8001/pm8001_sas.c
> @@ -383,7 +383,7 @@ static int pm8001_task_exec(struct sas_task *task,
>   	struct sas_task *t = task;
>   	struct task_status_struct *ts = &t->task_status;
>   	struct pm8001_ccb_info *ccb;
> -	u32 tag = 0xdeadbeef, rc = 0, n_elem = 0;
> +	u32 tag = 0xdeadbeef, rc = 0, n_elem;
>   	unsigned long flags = 0;
>   	enum sas_protocol task_proto = t->task_proto;
>   
> @@ -440,6 +440,8 @@ static int pm8001_task_exec(struct sas_task *task,
>   					rc = -ENOMEM;
>   					goto err_out_tag;
>   				}
> +			} else {
> +				n_elem = 0;
>   			}
>   		} else {
>   			n_elem = t->num_scatter;