scsi: Use 'SCSIRequest' directly

Currently the SCSIRequest structure is abstracted away and cannot accessed
directly from the driver. This requires the handler to do a lookup on
an abstract 'tag' which identifies the SCSIRequest structure.

With this patch the SCSIRequest structure is exposed to the driver. This
allows use to use it directly as an argument to the SCSIDeviceInfo
callback functions and remove the lookup.

A new callback function 'alloc_req' is introduced matching 'free
req'; unref'ing to free up resources after use is moved into the
scsi_command_complete callbacks.

This temporarily introduces a leak of requests that are cancelled,
when they are removed from the queue and not from the driver.  This
is fixed later by introducing scsi_req_cancel.  That patch in turn
depends on this one, because the argument to scsi_req_cancel is a
SCSIRequest.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 15 insertions, 12 deletions

diff --git a/hw/usb-msd.c b/hw/usb-msd.c
index c0a381abb3..8e6d48bf25 100644
--- a/hw/usb-msd.c
+++ b/hw/usb-msd.c
@@ -48,6 +48,7 @@ typedef struct {
     uint32_t data_len;
     uint32_t residue;
     uint32_t tag;
+    SCSIRequest *req;
     SCSIBus bus;
     BlockConf conf;
     SCSIDevice *scsi_dev;
@@ -190,9 +191,9 @@ static void usb_msd_copy_data(MSDState *s)
     s->data_len -= len;
     if (s->scsi_len == 0 || s->data_len == 0) {
         if (s->mode == USB_MSDM_DATAIN) {
-            s->scsi_dev->info->read_data(s->scsi_dev, s->tag);
+            s->scsi_dev->info->read_data(s->req);
         } else if (s->mode == USB_MSDM_DATAOUT) {
-            s->scsi_dev->info->write_data(s->scsi_dev, s->tag);
+            s->scsi_dev->info->write_data(s->req);
         }
     }
 }
@@ -211,14 +212,13 @@ static void usb_msd_send_status(MSDState *s, USBPacket *p)
     memcpy(p->data, &csw, len);
 }
 
-static void usb_msd_command_complete(SCSIBus *bus, int reason, uint32_t tag,
-                                     uint32_t arg)
+static void usb_msd_command_complete(SCSIRequest *req, int reason, uint32_t arg)
 {
-    MSDState *s = DO_UPCAST(MSDState, dev.qdev, bus->qbus.parent);
+    MSDState *s = DO_UPCAST(MSDState, dev.qdev, req->bus->qbus.parent);
     USBPacket *p = s->packet;
 
-    if (tag != s->tag) {
-        fprintf(stderr, "usb-msd: Unexpected SCSI Tag 0x%x\n", tag);
+    if (req->tag != s->tag) {
+        fprintf(stderr, "usb-msd: Unexpected SCSI Tag 0x%x\n", req->tag);
     }
     if (reason == SCSI_REASON_DONE) {
         DPRINTF("Command complete %d\n", arg);
@@ -245,10 +245,12 @@ static void usb_msd_command_complete(SCSIBus *bus, int reason, uint32_t tag,
         } else if (s->data_len == 0) {
             s->mode = USB_MSDM_CSW;
         }
+        scsi_req_unref(req);
+        s->req = NULL;
         return;
     }
     s->scsi_len = arg;
-    s->scsi_buf = s->scsi_dev->info->get_buf(s->scsi_dev, tag);
+    s->scsi_buf = s->scsi_dev->info->get_buf(req);
     if (p) {
         usb_msd_copy_data(s);
         if (s->usb_len == 0) {
@@ -316,7 +318,7 @@ static int usb_msd_handle_control(USBDevice *dev, int request, int value,
 static void usb_msd_cancel_io(USBPacket *p, void *opaque)
 {
     MSDState *s = opaque;
-    s->scsi_dev->info->cancel_io(s->scsi_dev, s->tag);
+    s->scsi_dev->info->cancel_io(s->req);
     s->packet = NULL;
     s->scsi_len = 0;
 }
@@ -365,14 +367,15 @@ static int usb_msd_handle_data(USBDevice *dev, USBPacket *p)
                     s->tag, cbw.flags, cbw.cmd_len, s->data_len);
             s->residue = 0;
             s->scsi_len = 0;
-            s->scsi_dev->info->send_command(s->scsi_dev, s->tag, cbw.cmd, 0);
+            s->req = s->scsi_dev->info->alloc_req(s->scsi_dev, s->tag, 0);
+            s->scsi_dev->info->send_command(s->req, cbw.cmd);
             /* ??? Should check that USB and SCSI data transfer
                directions match.  */
             if (s->residue == 0) {
                 if (s->mode == USB_MSDM_DATAIN) {
-                    s->scsi_dev->info->read_data(s->scsi_dev, s->tag);
+                    s->scsi_dev->info->read_data(s->req);
                 } else if (s->mode == USB_MSDM_DATAOUT) {
-                    s->scsi_dev->info->write_data(s->scsi_dev, s->tag);
+                    s->scsi_dev->info->write_data(s->req);
                 }
             }
             ret = len;