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, 16 insertions, 11 deletions

diff --git a/hw/esp.c b/hw/esp.c
index ae18401..57061ca 100644
--- a/hw/esp.c
+++ b/hw/esp.c
@@ -65,6 +65,7 @@ struct ESPState {
     uint32_t dma;
     SCSIBus bus;
     SCSIDevice *current_dev;
+    SCSIRequest *current_req;
     uint8_t cmdbuf[TI_BUFSZ];
     uint32_t cmdlen;
     uint32_t do_cmd;
@@ -209,7 +210,7 @@ static uint32_t get_cmd(ESPState *s, uint8_t *buf)
 
     if (s->current_dev) {
         /* Started a new command before the old one finished.  Cancel it.  */
-        s->current_dev->info->cancel_io(s->current_dev, 0);
+        s->current_dev->info->cancel_io(s->current_req);
         s->async_len = 0;
     }
 
@@ -232,7 +233,8 @@ static void do_busid_cmd(ESPState *s, uint8_t *buf, uint8_t busid)
 
     DPRINTF("do_busid_cmd: busid 0x%x\n", busid);
     lun = busid & 7;
-    datalen = s->current_dev->info->send_command(s->current_dev, 0, buf, lun);
+    s->current_req = s->current_dev->info->alloc_req(s->current_dev, 0, lun);
+    datalen = s->current_dev->info->send_command(s->current_req, buf);
     s->ti_size = datalen;
     if (datalen != 0) {
         s->rregs[ESP_RSTAT] = STAT_TC;
@@ -240,10 +242,10 @@ static void do_busid_cmd(ESPState *s, uint8_t *buf, uint8_t busid)
         s->dma_counter = 0;
         if (datalen > 0) {
             s->rregs[ESP_RSTAT] |= STAT_DI;
-            s->current_dev->info->read_data(s->current_dev, 0);
+            s->current_dev->info->read_data(s->current_req);
         } else {
             s->rregs[ESP_RSTAT] |= STAT_DO;
-            s->current_dev->info->write_data(s->current_dev, 0);
+            s->current_dev->info->write_data(s->current_req);
         }
     }
     s->rregs[ESP_RINTR] = INTR_BS | INTR_FC;
@@ -372,9 +374,9 @@ static void esp_do_dma(ESPState *s)
     if (s->async_len == 0) {
         if (to_device) {
             // ti_size is negative
-            s->current_dev->info->write_data(s->current_dev, 0);
+            s->current_dev->info->write_data(s->current_req);
         } else {
-            s->current_dev->info->read_data(s->current_dev, 0);
+            s->current_dev->info->read_data(s->current_req);
             /* If there is still data to be read from the device then
                complete the DMA operation immediately.  Otherwise defer
                until the scsi layer has completed.  */
@@ -388,10 +390,9 @@ static void esp_do_dma(ESPState *s)
     }
 }
 
-static void esp_command_complete(SCSIBus *bus, int reason, uint32_t tag,
-                                 uint32_t arg)
+static void esp_command_complete(SCSIRequest *req, int reason, uint32_t arg)
 {
-    ESPState *s = DO_UPCAST(ESPState, busdev.qdev, bus->qbus.parent);
+    ESPState *s = DO_UPCAST(ESPState, busdev.qdev, req->bus->qbus.parent);
 
     if (reason == SCSI_REASON_DONE) {
         DPRINTF("SCSI Command complete\n");
@@ -405,11 +406,15 @@ static void esp_command_complete(SCSIBus *bus, int reason, uint32_t tag,
         s->sense = arg;
         s->rregs[ESP_RSTAT] = STAT_ST;
         esp_dma_done(s);
-        s->current_dev = NULL;
+        if (s->current_req) {
+            scsi_req_unref(s->current_req);
+            s->current_req = NULL;
+            s->current_dev = NULL;
+        }
     } else {
         DPRINTF("transfer %d/%d\n", s->dma_left, s->ti_size);
         s->async_len = arg;
-        s->async_buf = s->current_dev->info->get_buf(s->current_dev, 0);
+        s->async_buf = s->current_dev->info->get_buf(req);
         if (s->dma_left) {
             esp_do_dma(s);
         } else if (s->dma_counter != 0 && s->ti_size <= 0) {