block: Mark bdrv_child_perm() GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_child_perm() need to hold a reader lock for the graph because
some implementations access the children list of a node.

The callers of bdrv_child_perm() conveniently already hold the lock.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-16-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

3 files changed, 16 insertions, 15 deletions

diff --git a/block.c b/block.c
index 186efda..0f7f78f 100644
--- a/block.c
+++ b/block.c
@@ -2228,11 +2228,12 @@ bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp)
     return false;
 }
 
-static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
-                            BdrvChild *c, BdrvChildRole role,
-                            BlockReopenQueue *reopen_queue,
-                            uint64_t parent_perm, uint64_t parent_shared,
-                            uint64_t *nperm, uint64_t *nshared)
+static void GRAPH_RDLOCK
+bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
+                BdrvChild *c, BdrvChildRole role,
+                BlockReopenQueue *reopen_queue,
+                uint64_t parent_perm, uint64_t parent_shared,
+                uint64_t *nperm, uint64_t *nshared)
 {
     assert(bs->drv && bs->drv->bdrv_child_perm);
     GLOBAL_STATE_CODE();
diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index 9a0e2b6..aeaff3b 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -341,11 +341,11 @@ static void cbw_refresh_filename(BlockDriverState *bs)
             bs->file->bs->filename);
 }
 
-static void cbw_child_perm(BlockDriverState *bs, BdrvChild *c,
-                           BdrvChildRole role,
-                           BlockReopenQueue *reopen_queue,
-                           uint64_t perm, uint64_t shared,
-                           uint64_t *nperm, uint64_t *nshared)
+static void GRAPH_RDLOCK
+cbw_child_perm(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role,
+               BlockReopenQueue *reopen_queue,
+               uint64_t perm, uint64_t shared,
+               uint64_t *nperm, uint64_t *nshared)
 {
     if (!(role & BDRV_CHILD_FILTERED)) {
         /*
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index f82c14f..3feb67e 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -451,11 +451,11 @@ struct BlockDriver {
      * permissions, but those that will be needed after applying the
      * @reopen_queue.
      */
-     void (*bdrv_child_perm)(BlockDriverState *bs, BdrvChild *c,
-                             BdrvChildRole role,
-                             BlockReopenQueue *reopen_queue,
-                             uint64_t parent_perm, uint64_t parent_shared,
-                             uint64_t *nperm, uint64_t *nshared);
+     void GRAPH_RDLOCK_PTR (*bdrv_child_perm)(
+        BlockDriverState *bs, BdrvChild *c, BdrvChildRole role,
+        BlockReopenQueue *reopen_queue,
+        uint64_t parent_perm, uint64_t parent_shared,
+        uint64_t *nperm, uint64_t *nshared);
 
     /**
      * Register/unregister a buffer for I/O. For example, when the driver is