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Re: [Qemu-devel] [PATCH V3 13/13] hw/sd.c: introduce "eject" property fo


From: Igor Mitsyanko
Subject: Re: [Qemu-devel] [PATCH V3 13/13] hw/sd.c: introduce "eject" property for SD card objects
Date: Mon, 30 Apr 2012 01:48:00 +0300
User-agent: Mozilla/5.0 (Windows NT 5.2; WOW64; rv:11.0) Gecko/20120327 Thunderbird/11.0.1

On 28.04.2012 5:27 PM, Paolo Bonzini wrote:
Il 27/04/2012 17:50, Igor Mitsyanko ha scritto:
Boolean property "eject" could be used to query if virtual media is inserted 
into
SD card object, or to deattach BlockDriverState from SD card object.

All this is already available in the BlockDriverState object; the eject
monitor command does bdrv_close and calls the change_media_cb on the
attached device.  The SD card should just attach callbacks to the BDS.


The idea here was to allow for detaching BlockDriverState from SDCard while detached BlockDriverState object still exist in QEMU and could be attached to another block frontend or deallocated if it's no longer needed, how else "drive_del" command can work?

But I want to say, after I used this property a bit I've realized that its not doing what I really wanted it to. It shouldn't call bdrv_close(), what it should do is to call bdrv_flush() and bdrv_dev_change_media_cb() and then bdrv_detach_dev(), this way there will be no link between SD card and BlockDriverState objects but image file will still be attached to BlockDriverState and could be used in another SD card object by setting its SDState::"drive" property appropriately.

Paolo

Signed-off-by: Igor Mitsyanko<address@hidden>
---
  hw/sd.c |   60 +++++++++++++++++++++++++++++++++++++++++++++++++++---------
  1 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/hw/sd.c b/hw/sd.c
index d067ffb..de57000 100644
--- a/hw/sd.c
+++ b/hw/sd.c
@@ -508,6 +508,19 @@ static void sd_init_card(SDState *sd, BlockDriverState 
*bdrv, Error **errp)
      }
  }

+static void sd_deinit_card(SDState *sd)
+{
+    bdrv_close(sd->bdrv);
+    sd->enable = false;
+    bdrv_detach_dev(sd->bdrv, sd);
+    sd_reset(sd, NULL);
+
+    if (sd->buf) {
+        qemu_vfree(sd->buf);
+        sd->buf = NULL;
+    }
+}
+
  static void sd_set_callbacks(SDState *sd, qemu_irq readonly, qemu_irq insert)
  {
      sd->readonly_cb = readonly;
@@ -1828,15 +1841,7 @@ static void sd_devid_set(Object *obj, const char *value, 
Error **errp)
              return;
          }

-        bdrv_close(sd->bdrv);
-        sd->enable = false;
-        bdrv_detach_dev(sd->bdrv, sd);
-        if (sd->buf) {
-            qemu_vfree(sd->buf);
-            sd->buf = NULL;
-        }
-        sd_reset(sd, NULL);
-
+        sd_deinit_card(sd);
          sd_init_card(sd, bdrv, errp);
          if (error_is_set(errp)) {
              vmstate_unregister(NULL,&sd_vmstate, sd);
@@ -1850,6 +1855,41 @@ static void sd_devid_set(Object *obj, const char *value, 
Error **errp)
      }
  }

+static void sd_is_ejected(Object *obj, Visitor *v, void *opaque,
+                         const char *name, Error **errp)
+{
+    SDState *sd = SD_CARD(obj);
+    bool ejected = sd->bdrv&&  bdrv_is_inserted(sd->bdrv) ? false : true;
+
+    visit_type_bool(v,&ejected, name, errp);
+}
+
+static void sd_eject(Object *obj, Visitor *v, void *opaque,
+                         const char *name, Error **errp)
+{
+    SDState *sd = SD_CARD(obj);
+    bool eject;
+
+    visit_type_bool(v,&eject, name, errp);
+    if (error_is_set(errp)) {
+        return;
+    }
+
+    if (eject) {
+        if (!sd->bdrv) {
+            return;
+        }
+
+        if (bdrv_in_use(sd->bdrv)) {
+            error_set(errp, QERR_DEVICE_IN_USE, 
bdrv_get_device_name(sd->bdrv));
+            return;
+        }
+
+        vmstate_unregister(NULL,&sd_vmstate, sd);
+        sd_deinit_card(sd);
+    }
+}
+
  static void sd_initfn(Object *obj)
  {
      SDState *sd = SD_CARD(obj);
@@ -1859,6 +1899,8 @@ static void sd_initfn(Object *obj)
              NULL, NULL, NULL);
      object_property_add_str(OBJECT(sd), "device-id", sd_devid_get, 
sd_devid_set,
              NULL);
+    object_property_add(obj, "eject", "boolean", sd_is_ejected, sd_eject,
+            NULL, NULL, NULL);
  }

  static const TypeInfo sd_type_info = {







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