[v4,28/31] scsi: pm8001: Simplify pm8001_task_exec()

The main part of the pm8001_task_exec() function uses a do {} while(0)
loop that is useless and only makes the code harder to read. Remove this
loop. The unnecessary local variable t is also removed.

Additionally, avoid repeatedly declaring "struct task_status_struct *ts"
to handle error cases by declaring this variable for the entire function
scope. This allows simplifying the error cases, and together with the
addition of blank lines make the code more readable.

Finally, handling of the running_req counter is fixed to avoid
decrementing it without a corresponding incrementation in the case of
an invalid task protocol.

Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: John Garry <john.garry@huawei.com>
---
 drivers/scsi/pm8001/pm8001_sas.c | 174 ++++++++++++++-----------------
 1 file changed, 80 insertions(+), 94 deletions(-)

On Thu, Feb 17, 2022 at 2:30 PM Damien Le Moal
<damien.lemoal@opensource.wdc.com> wrote:
>
> The main part of the pm8001_task_exec() function uses a do {} while(0)
> loop that is useless and only makes the code harder to read. Remove this
> loop. The unnecessary local variable t is also removed.
>
> Additionally, avoid repeatedly declaring "struct task_status_struct *ts"
> to handle error cases by declaring this variable for the entire function
> scope. This allows simplifying the error cases, and together with the
> addition of blank lines make the code more readable.
>
> Finally, handling of the running_req counter is fixed to avoid
> decrementing it without a corresponding incrementation in the case of
> an invalid task protocol.
>
> Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> Reviewed-by: John Garry <john.garry@huawei.com>
Reviewed-by: Jack Wang <jinpu.wang@ionos.com>
> ---
>  drivers/scsi/pm8001/pm8001_sas.c | 174 ++++++++++++++-----------------
>  1 file changed, 80 insertions(+), 94 deletions(-)
>
> diff --git a/drivers/scsi/pm8001/pm8001_sas.c b/drivers/scsi/pm8001/pm8001_sas.c
> index 52507bc8f963..37aba0335f18 100644
> --- a/drivers/scsi/pm8001/pm8001_sas.c
> +++ b/drivers/scsi/pm8001/pm8001_sas.c
> @@ -373,129 +373,115 @@ static int sas_find_local_port_id(struct domain_device *dev)
>    * @is_tmf: if it is task management task.
>    * @tmf: the task management IU
>    */
> -static int pm8001_task_exec(struct sas_task *task,
> -       gfp_t gfp_flags, int is_tmf, struct pm8001_tmf_task *tmf)
> +static int pm8001_task_exec(struct sas_task *task, gfp_t gfp_flags, int is_tmf,
> +                           struct pm8001_tmf_task *tmf)
>  {
> +       struct task_status_struct *ts = &task->task_status;
> +       enum sas_protocol task_proto = task->task_proto;
>         struct domain_device *dev = task->dev;
> +       struct pm8001_device *pm8001_dev = dev->lldd_dev;
>         struct pm8001_hba_info *pm8001_ha;
> -       struct pm8001_device *pm8001_dev;
>         struct pm8001_port *port = NULL;
> -       struct sas_task *t = task;
>         struct pm8001_ccb_info *ccb;
> -       u32 rc = 0, n_elem = 0;
> -       unsigned long flags = 0;
> -       enum sas_protocol task_proto = t->task_proto;
> +       unsigned long flags;
> +       u32 n_elem = 0;
> +       int rc = 0;
>
>         if (!dev->port) {
> -               struct task_status_struct *tsm = &t->task_status;
> -               tsm->resp = SAS_TASK_UNDELIVERED;
> -               tsm->stat = SAS_PHY_DOWN;
> +               ts->resp = SAS_TASK_UNDELIVERED;
> +               ts->stat = SAS_PHY_DOWN;
>                 if (dev->dev_type != SAS_SATA_DEV)
> -                       t->task_done(t);
> +                       task->task_done(task);
>                 return 0;
>         }
> -       pm8001_ha = pm8001_find_ha_by_dev(task->dev);
> -       if (pm8001_ha->controller_fatal_error) {
> -               struct task_status_struct *ts = &t->task_status;
>
> +       pm8001_ha = pm8001_find_ha_by_dev(dev);
> +       if (pm8001_ha->controller_fatal_error) {
>                 ts->resp = SAS_TASK_UNDELIVERED;
> -               t->task_done(t);
> +               task->task_done(task);
>                 return 0;
>         }
> +
>         pm8001_dbg(pm8001_ha, IO, "pm8001_task_exec device\n");
> +
>         spin_lock_irqsave(&pm8001_ha->lock, flags);
> -       do {
> -               dev = t->dev;
> -               pm8001_dev = dev->lldd_dev;
> -               port = &pm8001_ha->port[sas_find_local_port_id(dev)];
> -               if (DEV_IS_GONE(pm8001_dev) || !port->port_attached) {
> -                       if (sas_protocol_ata(task_proto)) {
> -                               struct task_status_struct *ts = &t->task_status;
> -                               ts->resp = SAS_TASK_UNDELIVERED;
> -                               ts->stat = SAS_PHY_DOWN;
>
> -                               spin_unlock_irqrestore(&pm8001_ha->lock, flags);
> -                               t->task_done(t);
> -                               spin_lock_irqsave(&pm8001_ha->lock, flags);
> -                               continue;
> -                       } else {
> -                               struct task_status_struct *ts = &t->task_status;
> -                               ts->resp = SAS_TASK_UNDELIVERED;
> -                               ts->stat = SAS_PHY_DOWN;
> -                               t->task_done(t);
> -                               continue;
> -                       }
> -               }
> +       pm8001_dev = dev->lldd_dev;
> +       port = &pm8001_ha->port[sas_find_local_port_id(dev)];
>
> -               ccb = pm8001_ccb_alloc(pm8001_ha, pm8001_dev, t);
> -               if (!ccb) {
> -                       rc = -SAS_QUEUE_FULL;
> -                       goto err_out;
> +       if (DEV_IS_GONE(pm8001_dev) || !port->port_attached) {
> +               ts->resp = SAS_TASK_UNDELIVERED;
> +               ts->stat = SAS_PHY_DOWN;
> +               if (sas_protocol_ata(task_proto)) {
> +                       spin_unlock_irqrestore(&pm8001_ha->lock, flags);
> +                       task->task_done(task);
> +                       spin_lock_irqsave(&pm8001_ha->lock, flags);
> +               } else {
> +                       task->task_done(task);
>                 }
> +               rc = -ENODEV;
> +               goto err_out;
> +       }
>
> -               if (!sas_protocol_ata(task_proto)) {
> -                       if (t->num_scatter) {
> -                               n_elem = dma_map_sg(pm8001_ha->dev,
> -                                       t->scatter,
> -                                       t->num_scatter,
> -                                       t->data_dir);
> -                               if (!n_elem) {
> -                                       rc = -ENOMEM;
> -                                       goto err_out_ccb;
> -                               }
> +       ccb = pm8001_ccb_alloc(pm8001_ha, pm8001_dev, task);
> +       if (!ccb) {
> +               rc = -SAS_QUEUE_FULL;
> +               goto err_out;
> +       }
> +
> +       if (!sas_protocol_ata(task_proto)) {
> +               if (task->num_scatter) {
> +                       n_elem = dma_map_sg(pm8001_ha->dev, task->scatter,
> +                                           task->num_scatter, task->data_dir);
> +                       if (!n_elem) {
> +                               rc = -ENOMEM;
> +                               goto err_out_ccb;
>                         }
> -               } else {
> -                       n_elem = t->num_scatter;
>                 }
> +       } else {
> +               n_elem = task->num_scatter;
> +       }
>
> -               t->lldd_task = ccb;
> -               ccb->n_elem = n_elem;
> +       task->lldd_task = ccb;
> +       ccb->n_elem = n_elem;
>
> -               switch (task_proto) {
> -               case SAS_PROTOCOL_SMP:
> -                       atomic_inc(&pm8001_dev->running_req);
> -                       rc = pm8001_task_prep_smp(pm8001_ha, ccb);
> -                       break;
> -               case SAS_PROTOCOL_SSP:
> -                       atomic_inc(&pm8001_dev->running_req);
> -                       if (is_tmf)
> -                               rc = pm8001_task_prep_ssp_tm(pm8001_ha,
> -                                       ccb, tmf);
> -                       else
> -                               rc = pm8001_task_prep_ssp(pm8001_ha, ccb);
> -                       break;
> -               case SAS_PROTOCOL_SATA:
> -               case SAS_PROTOCOL_STP:
> -                       atomic_inc(&pm8001_dev->running_req);
> -                       rc = pm8001_task_prep_ata(pm8001_ha, ccb);
> -                       break;
> -               default:
> -                       dev_printk(KERN_ERR, pm8001_ha->dev,
> -                               "unknown sas_task proto: 0x%x\n", task_proto);
> -                       rc = -EINVAL;
> -                       break;
> -               }
> +       atomic_inc(&pm8001_dev->running_req);
>
> -               if (rc) {
> -                       pm8001_dbg(pm8001_ha, IO, "rc is %x\n", rc);
> -                       atomic_dec(&pm8001_dev->running_req);
> -                       goto err_out_ccb;
> -               }
> -               /* TODO: select normal or high priority */
> -       } while (0);
> -       rc = 0;
> -       goto out_done;
> +       switch (task_proto) {
> +       case SAS_PROTOCOL_SMP:
> +               rc = pm8001_task_prep_smp(pm8001_ha, ccb);
> +               break;
> +       case SAS_PROTOCOL_SSP:
> +               if (is_tmf)
> +                       rc = pm8001_task_prep_ssp_tm(pm8001_ha, ccb, tmf);
> +               else
> +                       rc = pm8001_task_prep_ssp(pm8001_ha, ccb);
> +               break;
> +       case SAS_PROTOCOL_SATA:
> +       case SAS_PROTOCOL_STP:
> +               rc = pm8001_task_prep_ata(pm8001_ha, ccb);
> +               break;
> +       default:
> +               dev_printk(KERN_ERR, pm8001_ha->dev,
> +                          "unknown sas_task proto: 0x%x\n", task_proto);
> +               rc = -EINVAL;
> +               break;
> +       }
>
> +       if (rc) {
> +               atomic_dec(&pm8001_dev->running_req);
> +               if (!sas_protocol_ata(task_proto) && n_elem)
> +                       dma_unmap_sg(pm8001_ha->dev, task->scatter,
> +                                    task->num_scatter, task->data_dir);
>  err_out_ccb:
> -       pm8001_ccb_free(pm8001_ha, ccb);
> +               pm8001_ccb_free(pm8001_ha, ccb);
> +
>  err_out:
> -       dev_printk(KERN_ERR, pm8001_ha->dev, "pm8001 exec failed[%d]!\n", rc);
> -       if (!sas_protocol_ata(task_proto))
> -               if (n_elem)
> -                       dma_unmap_sg(pm8001_ha->dev, t->scatter, t->num_scatter,
> -                               t->data_dir);
> -out_done:
> +               pm8001_dbg(pm8001_ha, IO, "pm8001_task_exec failed[%d]!\n", rc);
> +       }
> +
>         spin_unlock_irqrestore(&pm8001_ha->lock, flags);
> +
>         return rc;
>  }
>
> --
> 2.34.1
>