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, 25 insertions, 19 deletions

diff --git a/hw/spapr_vscsi.c b/hw/spapr_vscsi.c
index c183008e4..36dd7445a 100644
--- a/hw/spapr_vscsi.c
+++ b/hw/spapr_vscsi.c
@@ -75,6 +75,7 @@ typedef struct vscsi_req {
 
     /* SCSI request tracking */
     SCSIDevice              *sdev;
+    SCSIRequest             *sreq;
     uint32_t                qtag; /* qemu tag != srp tag */
     int                     lun;
     int                     active;
@@ -123,11 +124,16 @@ static struct vscsi_req *vscsi_get_req(VSCSIState *s)
 
 static void vscsi_put_req(VSCSIState *s, vscsi_req *req)
 {
+    if (req->sreq != NULL) {
+        scsi_req_unref(req->sreq);
+    }
+    req->sreq = NULL;
     req->active = 0;
 }
 
-static vscsi_req *vscsi_find_req(VSCSIState *s, uint32_t tag)
+static vscsi_req *vscsi_find_req(VSCSIState *s, SCSIRequest *req)
 {
+    uint32_t tag = req->tag;
     if (tag >= VSCSI_REQ_LIMIT || !s->reqs[tag].active) {
         return NULL;
     }
@@ -453,11 +459,11 @@ static void vscsi_send_request_sense(VSCSIState *s, vscsi_req *req)
     cdb[4] = 96;
     cdb[5] = 0;
     req->sensing = 1;
-    n = sdev->info->send_command(sdev, req->qtag, cdb, req->lun);
+    n = sdev->info->send_command(req->sreq, cdb);
     dprintf("VSCSI: Queued request sense tag 0x%x\n", req->qtag);
     if (n < 0) {
         fprintf(stderr, "VSCSI: REQUEST_SENSE wants write data !?!?!?\n");
-        sdev->info->cancel_io(sdev, req->qtag);
+        sdev->info->cancel_io(req->sreq);
         vscsi_makeup_sense(s, req, HARDWARE_ERROR, 0, 0);
         vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0);
         vscsi_put_req(s, req);
@@ -465,24 +471,23 @@ static void vscsi_send_request_sense(VSCSIState *s, vscsi_req *req)
     } else if (n == 0) {
         return;
     }
-    sdev->info->read_data(sdev, req->qtag);
+    sdev->info->read_data(req->sreq);
 }
 
 /* Callback to indicate that the SCSI layer has completed a transfer.  */
-static void vscsi_command_complete(SCSIBus *bus, int reason, uint32_t tag,
-                                   uint32_t arg)
+static void vscsi_command_complete(SCSIRequest *sreq, int reason, uint32_t arg)
 {
-    VSCSIState *s = DO_UPCAST(VSCSIState, vdev.qdev, bus->qbus.parent);
-    vscsi_req *req = vscsi_find_req(s, tag);
+    VSCSIState *s = DO_UPCAST(VSCSIState, vdev.qdev, sreq->bus->qbus.parent);
+    vscsi_req *req = vscsi_find_req(s, sreq);
     SCSIDevice *sdev;
     uint8_t *buf;
     int32_t res_in = 0, res_out = 0;
     int len, rc = 0;
 
     dprintf("VSCSI: SCSI cmd complete, r=0x%x tag=0x%x arg=0x%x, req=%p\n",
-            reason, tag, arg, req);
+            reason, sreq->tag, arg, req);
     if (req == NULL) {
-        fprintf(stderr, "VSCSI: Can't find request for tag 0x%x\n", tag);
+        fprintf(stderr, "VSCSI: Can't find request for tag 0x%x\n", sreq->tag);
         return;
     }
     sdev = req->sdev;
@@ -493,7 +498,7 @@ static void vscsi_command_complete(SCSIBus *bus, int reason, uint32_t tag,
             vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0);
             vscsi_put_req(s, req);
         } else {
-            uint8_t *buf = sdev->info->get_buf(sdev, tag);
+            uint8_t *buf = sdev->info->get_buf(sreq);
 
             len = MIN(arg, SCSI_SENSE_BUF_SIZE);
             dprintf("VSCSI: Sense data, %d bytes:\n", len);
@@ -505,7 +510,7 @@ static void vscsi_command_complete(SCSIBus *bus, int reason, uint32_t tag,
                     buf[12], buf[13], buf[14], buf[15]);
             memcpy(req->sense, buf, len);
             req->senselen = len;
-            sdev->info->read_data(sdev, req->qtag);
+            sdev->info->read_data(sreq);
         }
         return;
     }
@@ -537,12 +542,12 @@ static void vscsi_command_complete(SCSIBus *bus, int reason, uint32_t tag,
      * to write for writes (ie, how much is to be DMA'd)
      */
     if (arg) {
-        buf = sdev->info->get_buf(sdev, tag);
+        buf = sdev->info->get_buf(sreq);
         rc = vscsi_srp_transfer_data(s, req, req->writing, buf, arg);
     }
     if (rc < 0) {
         fprintf(stderr, "VSCSI: RDMA error rc=%d!\n", rc);
-        sdev->info->cancel_io(sdev, req->qtag);
+        sdev->info->cancel_io(sreq);
         vscsi_makeup_sense(s, req, HARDWARE_ERROR, 0, 0);
         vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0);
         vscsi_put_req(s, req);
@@ -552,9 +557,9 @@ static void vscsi_command_complete(SCSIBus *bus, int reason, uint32_t tag,
     /* Start next chunk */
     req->data_len -= rc;
     if (req->writing) {
-        sdev->info->write_data(sdev, req->qtag);
+        sdev->info->write_data(sreq);
     } else {
-        sdev->info->read_data(sdev, req->qtag);
+        sdev->info->read_data(sreq);
     }
 }
 
@@ -644,7 +649,8 @@ static int vscsi_queue_cmd(VSCSIState *s, vscsi_req *req)
 
     req->sdev = sdev;
     req->lun = lun;
-    n = sdev->info->send_command(sdev, req->qtag, srp->cmd.cdb, lun);
+    req->sreq = sdev->info->alloc_req(sdev, req->qtag, lun);
+    n = sdev->info->send_command(req->sreq, srp->cmd.cdb);
 
     dprintf("VSCSI: Queued command tag 0x%x CMD 0x%x ID %d LUN %d ret: %d\n",
             req->qtag, srp->cmd.cdb[0], id, lun, n);
@@ -662,10 +668,10 @@ static int vscsi_queue_cmd(VSCSIState *s, vscsi_req *req)
     /* Get transfer direction and initiate transfer */
     if (n > 0) {
         req->data_len = n;
-        sdev->info->read_data(sdev, req->qtag);
+        sdev->info->read_data(req->sreq);
     } else if (n < 0) {
         req->data_len = -n;
-        sdev->info->write_data(sdev, req->qtag);
+        sdev->info->write_data(req->sreq);
     }
     /* Don't touch req here, it may have been recycled already */