> -----Original Message-----
> From: Hannes Reinecke [mailto:h...@suse.de]
> Sent: Friday, December 18, 2015 12:52 AM
> To: KY Srinivasan <k...@microsoft.com>; gre...@linuxfoundation.org; linux-
> ker...@vger.kernel.org; de...@linuxdriverproject.org; oher...@suse.com;
> jbottom...@parallels.com; h...@infradead.org; linux-s...@vger.kernel.org;
> a...@canonical.com; vkuzn...@redhat.com; jasow...@redhat.com;
> martin.peter...@oracle.com
> Subject: Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path
> 
> On 12/13/2015 09:28 PM, K. Y. Srinivasan wrote:
> > On the interrupt path, we repeatedly establish the pointer to the
> > storvsc_device. Fix this.
> >
> > Signed-off-by: K. Y. Srinivasan <k...@microsoft.com>
> > Reviewed-by: Long Li <lon...@microsoft.com>
> > Reviewed-by: Johannes Thumshirn <jthumsh...@suse.de>
> > Tested-by: Alex Ng <ale...@microsoft.com>
> > ---
> >   drivers/scsi/storvsc_drv.c |   23 ++++++++---------------
> >   1 files changed, 8 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> > index d6ca4f2..b68aebe 100644
> > --- a/drivers/scsi/storvsc_drv.c
> > +++ b/drivers/scsi/storvsc_drv.c
> > @@ -945,19 +945,16 @@ static void storvsc_handle_error(struct
> vmscsi_request *vm_srb,
> >   }
> >
> >
> > -static void storvsc_command_completion(struct storvsc_cmd_request
> *cmd_request)
> > +static void storvsc_command_completion(struct storvsc_cmd_request
> *cmd_request,
> > +                                  struct storvsc_device *stor_dev)
> >   {
> >     struct scsi_cmnd *scmnd = cmd_request->cmd;
> > -   struct hv_host_device *host_dev = shost_priv(scmnd->device-
> >host);
> >     struct scsi_sense_hdr sense_hdr;
> >     struct vmscsi_request *vm_srb;
> >     struct Scsi_Host *host;
> > -   struct storvsc_device *stor_dev;
> > -   struct hv_device *dev = host_dev->dev;
> >     u32 payload_sz = cmd_request->payload_sz;
> >     void *payload = cmd_request->payload;
> >
> > -   stor_dev = get_in_stor_device(dev);
> >     host = stor_dev->host;
> >
> >     vm_srb = &cmd_request->vstor_packet.vm_srb;
> > @@ -987,14 +984,13 @@ static void storvsc_command_completion(struct
> storvsc_cmd_request *cmd_request)
> >             kfree(payload);
> >   }
> >
> > -static void storvsc_on_io_completion(struct hv_device *device,
> > +static void storvsc_on_io_completion(struct storvsc_device *stor_device,
> >                               struct vstor_packet *vstor_packet,
> >                               struct storvsc_cmd_request *request)
> >   {
> > -   struct storvsc_device *stor_device;
> >     struct vstor_packet *stor_pkt;
> > +   struct hv_device *device = stor_device->device;
> >
> > -   stor_device = hv_get_drvdata(device);
> >     stor_pkt = &request->vstor_packet;
> >
> >     /*
> > @@ -1049,7 +1045,7 @@ static void storvsc_on_io_completion(struct
> hv_device *device,
> >     stor_pkt->vm_srb.data_transfer_length =
> >     vstor_packet->vm_srb.data_transfer_length;
> >
> > -   storvsc_command_completion(request);
> > +   storvsc_command_completion(request, stor_device);
> >
> >     if (atomic_dec_and_test(&stor_device->num_outstanding_req) &&
> >             stor_device->drain_notify)
> > @@ -1058,21 +1054,19 @@ static void storvsc_on_io_completion(struct
> hv_device *device,
> >
> >   }
> >
> > -static void storvsc_on_receive(struct hv_device *device,
> > +static void storvsc_on_receive(struct storvsc_device *stor_device,
> >                          struct vstor_packet *vstor_packet,
> >                          struct storvsc_cmd_request *request)
> >   {
> >     struct storvsc_scan_work *work;
> > -   struct storvsc_device *stor_device;
> >
> >     switch (vstor_packet->operation) {
> >     case VSTOR_OPERATION_COMPLETE_IO:
> > -           storvsc_on_io_completion(device, vstor_packet, request);
> > +           storvsc_on_io_completion(stor_device, vstor_packet,
> request);
> >             break;
> >
> >     case VSTOR_OPERATION_REMOVE_DEVICE:
> >     case VSTOR_OPERATION_ENUMERATE_BUS:
> > -           stor_device = get_in_stor_device(device);
> >             work = kmalloc(sizeof(struct storvsc_scan_work),
> GFP_ATOMIC);
> >             if (!work)
> >                     return;
> > @@ -1083,7 +1077,6 @@ static void storvsc_on_receive(struct hv_device
> *device,
> >             break;
> >
> >     case VSTOR_OPERATION_FCHBA_DATA:
> > -           stor_device = get_in_stor_device(device);
> >             cache_wwn(stor_device, vstor_packet);
> >   #ifdef CONFIG_SCSI_FC_ATTRS
> >             fc_host_node_name(stor_device->host) = stor_device-
> >node_name;
> > @@ -1133,7 +1126,7 @@ static void storvsc_on_channel_callback(void
> *context)
> >                                     vmscsi_size_delta));
> >                             complete(&request->wait_event);
> >                     } else {
> > -                           storvsc_on_receive(device,
> > +                           storvsc_on_receive(stor_device,
> >                                             (struct vstor_packet
> *)packet,
> >                                             request);
> >                     }
> >
> Hmm. I would've thought the compiler optimizes this away. Have you
> checked whether it actually makes a difference in the assembler output?

I have not checked the assembler output. It was easy enough to fix the source.

K. Y
> 
> Cheers,
> 
> Hannes
> --
> Dr. Hannes Reinecke                          zSeries & Storage
> h...@suse.de                                 +49 911 74053 688
> SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
> GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
> HRB 21284 (AG Nürnberg)
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