| Message ID | 20201203020806.14747-19-tyreld@linux.ibm.com |
|---|---|
| State | New |
| Headers | show |
| Series | ibmvfc: initial MQ development | expand |
On 12/2/20 8:08 PM, Tyrel Datwyler wrote: > The legacy CRQ holds the host lock the even while completing commands. > This presents a problem when in legacy single queue mode and > nr_hw_queues is greater than one since calling scsi_done() introduces > the potential for deadlock. > > If nr_hw_queues is greater than one drop the hostlock in the legacy CRQ > path when completing a command. > > Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com> > --- > drivers/scsi/ibmvscsi/ibmvfc.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c > index e499599662ec..e2200bdff2be 100644 > --- a/drivers/scsi/ibmvscsi/ibmvfc.c > +++ b/drivers/scsi/ibmvscsi/ibmvfc.c > @@ -2969,6 +2969,7 @@ static void ibmvfc_handle_crq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost) > { > long rc; > struct ibmvfc_event *evt = (struct ibmvfc_event *)be64_to_cpu(crq->ioba); > + unsigned long flags; > > switch (crq->valid) { > case IBMVFC_CRQ_INIT_RSP: > @@ -3039,7 +3040,12 @@ static void ibmvfc_handle_crq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost) > del_timer(&evt->timer); > list_del(&evt->queue); > ibmvfc_trc_end(evt); > - evt->done(evt); > + if (nr_scsi_hw_queues > 1) { > + spin_unlock_irqrestore(vhost->host->host_lock, flags); > + evt->done(evt); > + spin_lock_irqsave(vhost->host->host_lock, flags); > + } else > + evt->done(evt); Similar comment here as previously. The flags parameter is an output for spin_lock_irqsave but an input for spin_unlock_irqrestore. You'll need to rethink the locking here. You could just do a spin_unlock_irq / spin_lock_irq here and that would probably be OK, but probably isn't the best. > } > > /** > -- Brian King Power Linux I/O IBM Linux Technology Center
On 12/4/20 1:35 PM, Brian King wrote: > On 12/2/20 8:08 PM, Tyrel Datwyler wrote: >> The legacy CRQ holds the host lock the even while completing commands. >> This presents a problem when in legacy single queue mode and >> nr_hw_queues is greater than one since calling scsi_done() introduces >> the potential for deadlock. >> >> If nr_hw_queues is greater than one drop the hostlock in the legacy CRQ >> path when completing a command. >> >> Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com> >> --- >> drivers/scsi/ibmvscsi/ibmvfc.c | 8 +++++++- >> 1 file changed, 7 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c >> index e499599662ec..e2200bdff2be 100644 >> --- a/drivers/scsi/ibmvscsi/ibmvfc.c >> +++ b/drivers/scsi/ibmvscsi/ibmvfc.c >> @@ -2969,6 +2969,7 @@ static void ibmvfc_handle_crq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost) >> { >> long rc; >> struct ibmvfc_event *evt = (struct ibmvfc_event *)be64_to_cpu(crq->ioba); >> + unsigned long flags; >> >> switch (crq->valid) { >> case IBMVFC_CRQ_INIT_RSP: >> @@ -3039,7 +3040,12 @@ static void ibmvfc_handle_crq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost) >> del_timer(&evt->timer); >> list_del(&evt->queue); >> ibmvfc_trc_end(evt); >> - evt->done(evt); >> + if (nr_scsi_hw_queues > 1) { >> + spin_unlock_irqrestore(vhost->host->host_lock, flags); >> + evt->done(evt); >> + spin_lock_irqsave(vhost->host->host_lock, flags); >> + } else >> + evt->done(evt); > > Similar comment here as previously. The flags parameter is an output for > spin_lock_irqsave but an input for spin_unlock_irqrestore. You'll need > to rethink the locking here. You could just do a spin_unlock_irq / spin_lock_irq > here and that would probably be OK, but probably isn't the best. > Yeah, this will also get its own lock and flags saved in the per-queue struct in the next spin. -Tyrel >> } >> >> /** >> > >
diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c index e499599662ec..e2200bdff2be 100644 --- a/drivers/scsi/ibmvscsi/ibmvfc.c +++ b/drivers/scsi/ibmvscsi/ibmvfc.c @@ -2969,6 +2969,7 @@ static void ibmvfc_handle_crq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost) { long rc; struct ibmvfc_event *evt = (struct ibmvfc_event *)be64_to_cpu(crq->ioba); + unsigned long flags; switch (crq->valid) { case IBMVFC_CRQ_INIT_RSP: @@ -3039,7 +3040,12 @@ static void ibmvfc_handle_crq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost) del_timer(&evt->timer); list_del(&evt->queue); ibmvfc_trc_end(evt); - evt->done(evt); + if (nr_scsi_hw_queues > 1) { + spin_unlock_irqrestore(vhost->host->host_lock, flags); + evt->done(evt); + spin_lock_irqsave(vhost->host->host_lock, flags); + } else + evt->done(evt); } /**
The legacy CRQ holds the host lock the even while completing commands. This presents a problem when in legacy single queue mode and nr_hw_queues is greater than one since calling scsi_done() introduces the potential for deadlock. If nr_hw_queues is greater than one drop the hostlock in the legacy CRQ path when completing a command. Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com> --- drivers/scsi/ibmvscsi/ibmvfc.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)