Re: [PATCH 1/2] scsi: core: cleanup scsi_dev_queue_ready()

[Wenchao Hao]

On 2023/9/24 14:27, Wenchao Hao wrote:
> On 2023/9/22 20:50, Damien Le Moal wrote:
> > On 2023/09/22 2:38, Wenchao Hao wrote:
> > > This is just a cleanup for scsi_dev_queue_ready() to avoid
> > > redundant goto and if statement, it did not change the origin
> > > logic.
> > >
> > > Signed-off-by: Wenchao Hao <haowenchao2@xxxxxxxxxx>
> > > ---
> > >   drivers/scsi/scsi_lib.c | 35 ++++++++++++++++++-----------------
> > >   1 file changed, 18 insertions(+), 17 deletions(-)
> > >
> > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> > > index ca5eb058d5c7..f3e388127dbd 100644
> > > --- a/drivers/scsi/scsi_lib.c
> > > +++ b/drivers/scsi/scsi_lib.c
> > > @@ -1254,28 +1254,29 @@ static inline int scsi_dev_queue_ready(struct request_queue *q,
> > >       int token;
> > >       token = sbitmap_get(&sdev->budget_map);
> > > -    if (atomic_read(&sdev->device_blocked)) {
> > > -        if (token < 0)
> > > -            goto out;
> > > +    if (token < 0)
> > > +        return -1;
> >
> > This is changing how this function works...
>
> I don't think so...
> The origin function flow:
>
> static inline int scsi_dev_queue_ready(struct request_queue *q,
>                    struct scsi_device *sdev)
> {
>      ...
>      token = sbitmap_get(&sdev->budget_map);
>      if (atomic_read(&sdev->device_blocked)) {
>          if (token < 0)
>              goto out;
>      }
>      return token;
> out:
>      return -1
> }
>
> If the token is less than 0, it would always return -1. So we can found
> it's not necessary to check token after atomic_read().
>
> > > -        if (scsi_device_busy(sdev) > 1)
> > > -            goto out_dec;
> > > +    /*
> > > +     * device_blocked is not set at mostly time, so check it first
> > > +     * and return token when it is not set.
> > > +     */
> > > +    if (!atomic_read(&sdev->device_blocked))
> > > +        return token;
> >
> > ...because you reversed the tests order.
>
> As explained in comment, the device_blocked is not set at mostly time,
> so when it's not set, just return the token.

Friendly ping...