Re: [PATCH v3 4/7] libsas: add sas event wait-complete support
From: Hannes Reinecke
Date: Fri Jul 14 2017 - 02:51:13 EST
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.
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 NÃrnberg
GF: F. ImendÃrffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG NÃrnberg)