Re: [PATCH v3 4/7] libsas: add sas event wait-complete support

From: wangyijing
Date: Fri Jul 14 2017 - 03:47:06 EST



å 2017/7/14 14:51, Hannes Reinecke åé:
> On 07/10/2017 09:06 AM, Yijing Wang wrote:
>> Introduce wait-complete for libsas sas event processing,
>> execute sas port create/destruct in sync.
>>
>> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
>> CC: John Garry <john.garry@xxxxxxxxxx>
>> CC: Johannes Thumshirn <jthumshirn@xxxxxxx>
>> CC: Ewan Milne <emilne@xxxxxxxxxx>
>> CC: Christoph Hellwig <hch@xxxxxx>
>> CC: Tomas Henzl <thenzl@xxxxxxxxxx>
>> CC: Dan Williams <dan.j.williams@xxxxxxxxx>
>> ---
>> drivers/scsi/libsas/sas_discover.c | 41 ++++++++++++++++++++++++++++----------
>> drivers/scsi/libsas/sas_internal.h | 34 +++++++++++++++++++++++++++++++
>> drivers/scsi/libsas/sas_port.c | 4 ++++
>> include/scsi/libsas.h | 5 ++++-
>> 4 files changed, 72 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
>> index 60de662..5d4a3a8 100644
>> --- a/drivers/scsi/libsas/sas_discover.c
>> +++ b/drivers/scsi/libsas/sas_discover.c
>> @@ -525,16 +525,43 @@ static void sas_revalidate_domain(struct work_struct *work)
>> mutex_unlock(&ha->disco_mutex);
>> }
>>
>> +static const work_func_t sas_event_fns[DISC_NUM_EVENTS] = {
>> + [DISCE_DISCOVER_DOMAIN] = sas_discover_domain,
>> + [DISCE_REVALIDATE_DOMAIN] = sas_revalidate_domain,
>> + [DISCE_PROBE] = sas_probe_devices,
>> + [DISCE_SUSPEND] = sas_suspend_devices,
>> + [DISCE_RESUME] = sas_resume_devices,
>> + [DISCE_DESTRUCT] = sas_destruct_devices,
>> +};
>> +
>> +/* a simple wrapper for sas discover event funtions */
>> +static void sas_discover_common_fn(struct work_struct *work)
>> +{
>> + struct sas_discovery_event *ev = to_sas_discovery_event(work);
>> + struct asd_sas_port *port = ev->port;
>> +
>> + sas_event_fns[ev->type](work);
>> + sas_port_put(port);
>> +}
>> +
>> +
>> /* ---------- Events ---------- */
>>
>> static void sas_chain_work(struct sas_ha_struct *ha, struct sas_work *sw)
>> {
>> + int ret;
>> + struct sas_discovery_event *ev = to_sas_discovery_event(&sw->work);
>> + struct asd_sas_port *port = ev->port;
>> +
>> /* chained work is not subject to SA_HA_DRAINING or
>> * SAS_HA_REGISTERED, because it is either submitted in the
>> * workqueue, or known to be submitted from a context that is
>> * not racing against draining
>> */
>> - scsi_queue_work(ha->core.shost, &sw->work);
>> + sas_port_get(port);
>> + ret = scsi_queue_work(ha->core.shost, &sw->work);
>> + if (ret != 1)
>> + sas_port_put(port);
>> }
>>
>> static void sas_chain_event(int event, unsigned long *pending,
>> @@ -575,18 +602,10 @@ void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *port)
>> {
>> int i;
>>
>> - static const work_func_t sas_event_fns[DISC_NUM_EVENTS] = {
>> - [DISCE_DISCOVER_DOMAIN] = sas_discover_domain,
>> - [DISCE_REVALIDATE_DOMAIN] = sas_revalidate_domain,
>> - [DISCE_PROBE] = sas_probe_devices,
>> - [DISCE_SUSPEND] = sas_suspend_devices,
>> - [DISCE_RESUME] = sas_resume_devices,
>> - [DISCE_DESTRUCT] = sas_destruct_devices,
>> - };
>> -
>> disc->pending = 0;
>> for (i = 0; i < DISC_NUM_EVENTS; i++) {
>> - INIT_SAS_WORK(&disc->disc_work[i].work, sas_event_fns[i]);
>> + INIT_SAS_WORK(&disc->disc_work[i].work, sas_discover_common_fn);
>> disc->disc_work[i].port = port;
>> + disc->disc_work[i].type = i;
>> }
>> }
>> diff --git a/drivers/scsi/libsas/sas_internal.h b/drivers/scsi/libsas/sas_internal.h
>> index f03ce64..890b5d26 100644
>> --- a/drivers/scsi/libsas/sas_internal.h
>> +++ b/drivers/scsi/libsas/sas_internal.h
>> @@ -100,6 +100,40 @@ void sas_free_device(struct kref *kref);
>> extern const work_func_t sas_phy_event_fns[PHY_NUM_EVENTS];
>> extern const work_func_t sas_port_event_fns[PORT_NUM_EVENTS];
>>
>> +static void sas_complete_event(struct kref *kref)
>> +{
>> + struct asd_sas_port *port = container_of(kref, struct asd_sas_port, ref);
>> +
>> + complete_all(&port->completion);
>> +}
>> +
>> +static inline void sas_port_put(struct asd_sas_port *port)
>> +{
>> + if (port->is_sync)
>> + kref_put(&port->ref, sas_complete_event);
>> +}
>> +
>> +static inline void sas_port_wait_init(struct asd_sas_port *port)
>> +{
>> + init_completion(&port->completion);
>> + kref_init(&port->ref);
>> + port->is_sync = true;
>> +}
>> +
>> +static inline void sas_port_wait_completion(
>> + struct asd_sas_port *port)
>> +{
>> + sas_port_put(port);
>> + wait_for_completion(&port->completion);
>> + port->is_sync = false;
>> +}
>> +
>> +static inline void sas_port_get(struct asd_sas_port *port)
>> +{
>> + if (port && port->is_sync)
>> + kref_get(&port->ref);
>> +}
>> +
>> #ifdef CONFIG_SCSI_SAS_HOST_SMP
>> extern int sas_smp_host_handler(struct Scsi_Host *shost, struct request *req,
>> struct request *rsp);
>> diff --git a/drivers/scsi/libsas/sas_port.c b/drivers/scsi/libsas/sas_port.c
>> index 9326628..d589adb 100644
>> --- a/drivers/scsi/libsas/sas_port.c
>> +++ b/drivers/scsi/libsas/sas_port.c
>> @@ -191,7 +191,9 @@ static void sas_form_port(struct asd_sas_phy *phy)
>> if (si->dft->lldd_port_formed)
>> si->dft->lldd_port_formed(phy);
>>
>> + sas_port_wait_init(port);
>> sas_discover_event(phy->port, DISCE_DISCOVER_DOMAIN);
>> + sas_port_wait_completion(port);
>> }
>>
>> /**
>> @@ -218,7 +220,9 @@ void sas_deform_port(struct asd_sas_phy *phy, int gone)
>> dev->pathways--;
>>
>> if (port->num_phys == 1) {
>> + sas_port_wait_init(port);
>> sas_unregister_domain_devices(port, gone);
>> + sas_port_wait_completion(port);
>> sas_port_delete(port->port);
>> port->port = NULL;
>> } else {
>
> I would rather use the standard on-stack completion here;
> like this:
>
> DECLARE_COMPLETION_ONSTACK(complete);
> port->completion = &complete;
> sas_unregister_domain_devices(port, gone);
> wait_for_completion(&complete);
> sas_port_delete(port->port);
>
> which would simplify the above helpers to:
>
> static inline void sas_port_put(struct asd_sas_port *port)
> {
> if (port->completion)
> kref_put(&port->ref, sas_complete_event);
> }
>
> and you could do away with the 'is_sync' helper.

It looks better, thanks!

>
> Cheers,
>
> Hannes
>