[v1] Graph locking, part 3 (more block drivers)

[PATCH 11/20] vhdx: Take graph lock for accessing a node's parent list

Posted by Kevin Wolf 2 years, 9 months ago

This adds GRAPH_RDLOCK annotations to declare that functions accessing
the parent list of a node need to hold a reader lock for the graph. As
it happens, they already do.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vhdx.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/block/vhdx.c b/block/vhdx.c
index 00777da91a..b20b1edf11 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1506,8 +1506,9 @@ exit:
  * There are 2 headers, and the highest sequence number will represent
  * the active header
  */
-static int vhdx_create_new_headers(BlockBackend *blk, uint64_t image_size,
-                                   uint32_t log_size)
+static int coroutine_fn GRAPH_RDLOCK
+vhdx_create_new_headers(BlockBackend *blk, uint64_t image_size,
+                        uint32_t log_size)
 {
     BlockDriverState *bs = blk_bs(blk);
     BdrvChild *child;
@@ -1897,8 +1898,8 @@ exit:
  *    .---- ~ ----------- ~ ------------ ~ ---------------- ~ -----------.
  *   1MB
  */
-static int coroutine_fn vhdx_co_create(BlockdevCreateOptions *opts,
-                                       Error **errp)
+static int coroutine_fn GRAPH_RDLOCK
+vhdx_co_create(BlockdevCreateOptions *opts, Error **errp)
 {
     BlockdevCreateOptionsVhdx *vhdx_opts;
     BlockBackend *blk = NULL;
-- 
2.40.0

Re: [PATCH 11/20] vhdx: Take graph lock for accessing a node's parent list

Posted by Stefan Hajnoczi 2 years, 9 months ago

On Tue, Apr 25, 2023 at 07:31:49PM +0200, Kevin Wolf wrote:
> This adds GRAPH_RDLOCK annotations to declare that functions accessing
> the parent list of a node need to hold a reader lock for the graph. As
> it happens, they already do.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/vhdx.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)

The commit message is misleading. This commit does not take the graph
lock, it declares that the caller must already hold the graph lock.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

Re: [PATCH 11/20] vhdx: Take graph lock for accessing a node's parent list

Posted by Eric Blake 2 years, 9 months ago

On Tue, Apr 25, 2023 at 07:31:49PM +0200, Kevin Wolf wrote:
> This adds GRAPH_RDLOCK annotations to declare that functions accessing
> the parent list of a node need to hold a reader lock for the graph. As
> it happens, they already do.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/vhdx.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
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