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

[wangyijing <wangyijing@huawei.com>]

在 2017/7/14 14:51, Hannes Reinecke 写道:
> 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@huawei.com>
>> CC: John Garry <john.garry@huawei.com>
>> CC: Johannes Thumshirn <jthumshirn@suse.de>
>> CC: Ewan Milne <emilne@redhat.com>
>> CC: Christoph Hellwig <hch@lst.de>
>> CC: Tomas Henzl <thenzl@redhat.com>
>> CC: Dan Williams <dan.j.williams@intel.com>
>> ---
>>  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
>