diff mbox

[02/16] introduce a new API to check if blk is attached

Message ID 1441183880-26993-3-git-send-email-wency@cn.fujitsu.com
State New
Headers show

Commit Message

Wen Congyang Sept. 2, 2015, 8:51 a.m. UTC 
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 block.c                        | 4 ++--
 block/block-backend.c          | 9 +++++++++
 include/sysemu/block-backend.h | 1 +
 3 files changed, 12 insertions(+), 2 deletions(-)

Comments

Eric Blake Sept. 2, 2015, 3:40 p.m. UTC | #1 
On 09/02/2015 02:51 AM, Wen Congyang wrote:
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>  block.c                        | 4 ++--
>  block/block-backend.c          | 9 +++++++++
>  include/sysemu/block-backend.h | 1 +
>  3 files changed, 12 insertions(+), 2 deletions(-)
> 

>  /*
> + * Return true if a device model is attached to @blk already,
> + * otherwise, return false.
> + */
> +bool blk_is_attached(BlockBackend *blk)
> +{
> +    return blk != NULL && blk->dev != NULL && blk->dev != (void *)-1;

Again, I don't like the raw magic constant, even if we go with this
patch.  And it is shorter to write:

   return blk && blk->dev && blk->dev != MAGIC;

But I think it is better to just allow for a NULL BDS to represent an
unattached media (in which case Max's patches may already cover what you
are trying to do here), rather than trying to overload a special value
different from NULL.
diff mbox

Patch

diff --git a/block.c b/block.c
index 0f9029b..aeb365b 100644
--- a/block.c
+++ b/block.c
@@ -2089,7 +2089,7 @@  void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
     }
 
     /* bs_new must be unattached and shouldn't have anything fancy enabled */
-    assert(!bs_new->blk);
+    assert(!blk_is_attached(bs_new->blk));
     assert(QLIST_EMPTY(&bs_new->dirty_bitmaps));
     assert(bs_new->job == NULL);
     assert(bs_new->io_limits_enabled == false);
@@ -2106,7 +2106,7 @@  void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
     bdrv_move_feature_fields(bs_new, &tmp);
 
     /* bs_new must remain unattached */
-    assert(!bs_new->blk);
+    assert(!blk_is_attached(bs_new->blk));
 
     /* Check a few fields that should remain attached to the device */
     assert(bs_new->job == NULL);
diff --git a/block/block-backend.c b/block/block-backend.c
index 72d8b2c..1463c37 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -368,6 +368,15 @@  void blk_enable_attach_dev(BlockBackend *blk)
 }
 
 /*
+ * Return true if a device model is attached to @blk already,
+ * otherwise, return false.
+ */
+bool blk_is_attached(BlockBackend *blk)
+{
+    return blk != NULL && blk->dev != NULL && blk->dev != (void *)-1;
+}
+
+/*
  * Set @blk's device model callbacks to @ops.
  * @opaque is the opaque argument to pass to the callbacks.
  * This is for use by device models.
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 7619a9f..a8c6fd2 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -82,6 +82,7 @@  void blk_detach_dev(BlockBackend *blk, void *dev);
 void *blk_get_attached_dev(BlockBackend *blk);
 int blk_disable_attach_dev(BlockBackend *blk);
 void blk_enable_attach_dev(BlockBackend *blk);
+bool blk_is_attached(BlockBackend *blk);
 void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops, void *opaque);
 int blk_read(BlockBackend *blk, int64_t sector_num, uint8_t *buf,
              int nb_sectors);