Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path

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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 <kys@xxxxxxxxxxxxx>
Reviewed-by: Long Li <longli@xxxxxxxxxxxxx>
Reviewed-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
Tested-by: Alex Ng <alexng@xxxxxxxxxxxxx>
---
  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?

Cheers,

Hannes
--
Dr. Hannes Reinecke		               zSeries & Storage
hare@xxxxxxx			               +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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