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[PATCH v8 14/31] block: introduce assert_bdrv_graph_writable
From: |
Emanuele Giuseppe Esposito |
Subject: |
[PATCH v8 14/31] block: introduce assert_bdrv_graph_writable |
Date: |
Thu, 3 Mar 2022 10:15:59 -0500 |
We want to be sure that the functions that write the child and
parent list of a bs are under BQL and drain.
BQL prevents from concurrent writings from the GS API, while
drains protect from I/O.
TODO: drains are missing in some functions using this assert.
Therefore a proper assertion will fail. Because adding drains
requires additional discussions, they will be added in future
series.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
block.c | 4 ++++
include/block/block_int-global-state.h | 17 +++++++++++++++++
2 files changed, 21 insertions(+)
diff --git a/block.c b/block.c
index cf656e5b26..48daca835a 100644
--- a/block.c
+++ b/block.c
@@ -1420,6 +1420,7 @@ static void bdrv_child_cb_attach(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
+ assert_bdrv_graph_writable(bs);
QLIST_INSERT_HEAD(&bs->children, child, next);
if (child->role & BDRV_CHILD_COW) {
@@ -1439,6 +1440,7 @@ static void bdrv_child_cb_detach(BdrvChild *child)
bdrv_unapply_subtree_drain(child, bs);
+ assert_bdrv_graph_writable(bs);
QLIST_REMOVE(child, next);
}
@@ -2829,6 +2831,7 @@ static void bdrv_replace_child_noperm(BdrvChild **childp,
if (child->klass->detach) {
child->klass->detach(child);
}
+ assert_bdrv_graph_writable(old_bs);
QLIST_REMOVE(child, next_parent);
}
@@ -2838,6 +2841,7 @@ static void bdrv_replace_child_noperm(BdrvChild **childp,
}
if (new_bs) {
+ assert_bdrv_graph_writable(new_bs);
QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent);
/*
diff --git a/include/block/block_int-global-state.h
b/include/block/block_int-global-state.h
index 5078d6a6ea..0f21b0570b 100644
--- a/include/block/block_int-global-state.h
+++ b/include/block/block_int-global-state.h
@@ -309,4 +309,21 @@ void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
*/
void bdrv_drain_all_end_quiesce(BlockDriverState *bs);
+/**
+ * Make sure that the function is running under both drain and BQL.
+ * The latter protects from concurrent writings
+ * from the GS API, while the former prevents concurrent reads
+ * from I/O.
+ */
+static inline void assert_bdrv_graph_writable(BlockDriverState *bs)
+{
+ /*
+ * TODO: this function is incomplete. Because the users of this
+ * assert lack the necessary drains, check only for BQL.
+ * Once the necessary drains are added,
+ * assert also for qatomic_read(&bs->quiesce_counter) > 0
+ */
+ assert(qemu_in_main_thread());
+}
+
#endif /* BLOCK_INT_GLOBAL_STATE */
--
2.31.1
- [PATCH v8 07/31] include/sysemu/block-backend: split header into I/O and global state (GS) API, (continued)
- [PATCH v8 07/31] include/sysemu/block-backend: split header into I/O and global state (GS) API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 05/31] IO_CODE and IO_OR_GS_CODE for block I/O API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 03/31] include/block/block: split header into I/O and global state API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 09/31] IO_CODE and IO_OR_GS_CODE for block-backend I/O API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 10/31] block.c: assertions to the block layer permissions API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 12/31] assertions for block_int global state API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 11/31] include/block/block_int: split header into I/O and global state API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 16/31] GS and IO CODE macros for blockjob_int.h, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 15/31] include/block/blockjob_int.h: split header into I/O and GS API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 13/31] IO_CODE and IO_OR_GS_CODE for block_int I/O API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 14/31] block: introduce assert_bdrv_graph_writable,
Emanuele Giuseppe Esposito <=
- [PATCH v8 17/31] block.c: add assertions to static functions, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 19/31] assertions for blockjob.h global state API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 23/31] block/copy-before-write.h: global state API + assertions, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 25/31] block_int-common.h: split function pointers in BlockDriver, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 31/31] job.h: assertions in the callers of JobDriver function pointers, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 18/31] include/block/blockjob.h: global state API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 20/31] include/sysemu/blockdev.h: global state API, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 26/31] block_int-common.h: assertions in the callers of BlockDriver function pointers, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 22/31] include/block/snapshot: global state API + assertions, Emanuele Giuseppe Esposito, 2022/03/03
- [PATCH v8 21/31] assertions for blockdev.h global state API, Emanuele Giuseppe Esposito, 2022/03/03