Re: [PATCH net-next v4 03/18] net/smc: extract v2 check helper from SMC-D device registration

[Wen Gu]

On 2023/9/28 11:08, Jan Karcher wrote:
> On 24/09/2023 17:16, Wen Gu wrote:
> > This patch extracts v2-capable logic from the process of registering the
> > ISM device as an SMC-D device, so that the registration process of other
> > underlying devices can reuse it.
> >
> > Signed-off-by: Wen Gu <guwen@xxxxxxxxxxxxxxxxx>
> > ---
> >   net/smc/smc_ism.c | 29 ++++++++++++++++++-----------
> >   net/smc/smc_ism.h |  1 +
> >   2 files changed, 19 insertions(+), 11 deletions(-)
> >
> > diff --git a/net/smc/smc_ism.c b/net/smc/smc_ism.c
> > index 455ae0a..8f1ba74 100644
> > --- a/net/smc/smc_ism.c
> > +++ b/net/smc/smc_ism.c
> > @@ -69,6 +69,22 @@ bool smc_ism_is_v2_capable(void)
> >       return smc_ism_v2_capable;
> >   }
> > +/* must be called under smcd_dev_list.mutex lock */
> > +void smc_ism_check_v2_capable(struct smcd_dev *smcd)
> > +{
> > +    u8 *system_eid = NULL;
> > +
> > +    if (smc_ism_v2_capable)
> > +        return;
> > +
> > +    system_eid = smcd->ops->get_system_eid();
> > +    if (smcd->ops->supports_v2()) {
> > +        smc_ism_v2_capable = true;
> > +        memcpy(smc_ism_v2_system_eid, system_eid,
> > +               SMC_MAX_EID_LEN);
> > +    }
> > +}
> > +
> >   /* Set a connection using this DMBE. */
> >   void smc_ism_set_conn(struct smc_connection *conn)
> >   {
> > @@ -423,16 +439,7 @@ static void smcd_register_dev(struct ism_dev *ism)
> >           smc_pnetid_by_table_smcd(smcd);
> >       mutex_lock(&smcd_dev_list.mutex);
> > -    if (list_empty(&smcd_dev_list.list)) {
> > -        u8 *system_eid = NULL;
> > -
> > -        system_eid = smcd->ops->get_system_eid();
> > -        if (smcd->ops->supports_v2()) {
> > -            smc_ism_v2_capable = true;
> > -            memcpy(smc_ism_v2_system_eid, system_eid,
> > -                   SMC_MAX_EID_LEN);
> > -        }
> > -    }
> > +    smc_ism_check_v2_capable(smcd);
>
> The list_empty check is omitted here which means the smc_ism_check_v2_capable does not touch the list.
> So i think the call could be placed prior the mutex_lock.

Good catch. I omitted the list_empty check in this version but forget to remove 'the
lock comments' and place the helper prior to the mutex_lock. It will be fixed.

Thank you.

> >       /* sort list: devices without pnetid before devices with pnetid */
> >       if (smcd->pnetid[0])
> >           list_add_tail(&smcd->list, &smcd_dev_list.list);
> > @@ -535,10 +542,10 @@ int smc_ism_init(void)
> >   {
> >       int rc = 0;
> > -#if IS_ENABLED(CONFIG_ISM)
> >       smc_ism_v2_capable = false;
> >       memset(smc_ism_v2_system_eid, 0, SMC_MAX_EID_LEN);
> > +#if IS_ENABLED(CONFIG_ISM)
> >       rc = ism_register_client(&smc_ism_client);
> >   #endif
> >       return rc;
> > diff --git a/net/smc/smc_ism.h b/net/smc/smc_ism.h
> > index 832b2f4..14d2e77 100644
> > --- a/net/smc/smc_ism.h
> > +++ b/net/smc/smc_ism.h
> > @@ -42,6 +42,7 @@ int smc_ism_register_dmb(struct smc_link_group *lgr, int buf_size,
> >   void smc_ism_get_system_eid(u8 **eid);
> >   u16 smc_ism_get_chid(struct smcd_dev *dev);
> >   bool smc_ism_is_v2_capable(void);
> > +void smc_ism_check_v2_capable(struct smcd_dev *dev);
> >   int smc_ism_init(void);
> >   void smc_ism_exit(void);
> >   int smcd_nl_get_device(struct sk_buff *skb, struct netlink_callback *cb);