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From: Kevin Wolf <kwolf@redhat.com>
To: qemu-block@nongnu.org
Cc: kwolf@redhat.com,
qemu-devel@nongnu.org
Subject: [PULL 15/26] block: Mark bdrv_primary_child() and callers
GRAPH_RDLOCK
Date: Thu, 12 Oct 2023 18:22:13 +0200
Message-ID: <20231012162224.240535-16-kwolf@redhat.com>
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This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_primary_child() need to hold a reader lock for the graph
because it accesses the children list of a node.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230929145157.45443-12-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/block_int-io.h | 5 +++--
block.c | 11 ++++++++++-
block/snapshot.c | 3 +++
3 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/include/block/block_int-io.h b/include/block/block_int-io.h
index eb0da7232e..2b6004ab93 100644
--- a/include/block/block_int-io.h
+++ b/include/block/block_int-io.h
@@ -133,7 +133,7 @@ bdrv_refresh_total_sectors(BlockDriverState *bs, int64_=
t hint);
BdrvChild *bdrv_cow_child(BlockDriverState *bs);
BdrvChild *bdrv_filter_child(BlockDriverState *bs);
BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs);
-BdrvChild *bdrv_primary_child(BlockDriverState *bs);
+BdrvChild * GRAPH_RDLOCK bdrv_primary_child(BlockDriverState *bs);
BlockDriverState *bdrv_skip_filters(BlockDriverState *bs);
BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs);
=20
@@ -155,7 +155,8 @@ static inline BlockDriverState *bdrv_filter_or_cow_bs(B=
lockDriverState *bs)
return child_bs(bdrv_filter_or_cow_child(bs));
}
=20
-static inline BlockDriverState *bdrv_primary_bs(BlockDriverState *bs)
+static inline BlockDriverState * GRAPH_RDLOCK
+bdrv_primary_bs(BlockDriverState *bs)
{
IO_CODE();
return child_bs(bdrv_primary_child(bs));
diff --git a/block.c b/block.c
index 142e1d5e2b..6ce3e2ad7a 100644
--- a/block.c
+++ b/block.c
@@ -6692,7 +6692,8 @@ void coroutine_fn bdrv_co_debug_event(BlockDriverStat=
e *bs, BlkdebugEvent event)
bs->drv->bdrv_co_debug_event(bs, event);
}
=20
-static BlockDriverState *bdrv_find_debug_node(BlockDriverState *bs)
+static BlockDriverState * GRAPH_RDLOCK
+bdrv_find_debug_node(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) {
@@ -6711,6 +6712,8 @@ int bdrv_debug_breakpoint(BlockDriverState *bs, const=
char *event,
const char *tag)
{
GLOBAL_STATE_CODE();
+ GRAPH_RDLOCK_GUARD_MAINLOOP();
+
bs =3D bdrv_find_debug_node(bs);
if (bs) {
return bs->drv->bdrv_debug_breakpoint(bs, event, tag);
@@ -6722,6 +6725,8 @@ int bdrv_debug_breakpoint(BlockDriverState *bs, const=
char *event,
int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag)
{
GLOBAL_STATE_CODE();
+ GRAPH_RDLOCK_GUARD_MAINLOOP();
+
bs =3D bdrv_find_debug_node(bs);
if (bs) {
return bs->drv->bdrv_debug_remove_breakpoint(bs, tag);
@@ -6733,6 +6738,8 @@ int bdrv_debug_remove_breakpoint(BlockDriverState *bs=
, const char *tag)
int bdrv_debug_resume(BlockDriverState *bs, const char *tag)
{
GLOBAL_STATE_CODE();
+ GRAPH_RDLOCK_GUARD_MAINLOOP();
+
while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) {
bs =3D bdrv_primary_bs(bs);
}
@@ -6747,6 +6754,8 @@ int bdrv_debug_resume(BlockDriverState *bs, const cha=
r *tag)
bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag)
{
GLOBAL_STATE_CODE();
+ GRAPH_RDLOCK_GUARD_MAINLOOP();
+
while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) {
bs =3D bdrv_primary_bs(bs);
}
diff --git a/block/snapshot.c b/block/snapshot.c
index 554065578b..ad2bf6e068 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -311,7 +311,10 @@ int bdrv_snapshot_goto(BlockDriverState *bs,
* respective option (with the qdict_put_str() call above).
* Assert that .bdrv_open() has attached the right BDS as primary =
child.
*/
+ bdrv_graph_rdlock_main_loop();
assert(bdrv_primary_bs(bs) =3D=3D fallback_bs);
+ bdrv_graph_rdunlock_main_loop();
+
bdrv_unref(fallback_bs);
return ret;
}
--=20
2.41.0