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[PULL 46/51] block: assert that graph read and writes are performed corr
From: |
Kevin Wolf |
Subject: |
[PULL 46/51] block: assert that graph read and writes are performed correctly |
Date: |
Wed, 14 Dec 2022 14:44:48 +0100 |
From: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Remove the old assert_bdrv_graph_writable, and replace it with
the new version using graph-lock API.
See the function documentation for more information.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221207131838.239125-14-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/block_int-global-state.h | 17 -----------------
include/block/graph-lock.h | 15 +++++++++++++++
block.c | 4 ++--
block/graph-lock.c | 11 +++++++++++
4 files changed, 28 insertions(+), 19 deletions(-)
diff --git a/include/block/block_int-global-state.h
b/include/block/block_int-global-state.h
index b49f4eb35b..2f0993f6e9 100644
--- a/include/block/block_int-global-state.h
+++ b/include/block/block_int-global-state.h
@@ -310,21 +310,4 @@ 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_H */
diff --git a/include/block/graph-lock.h b/include/block/graph-lock.h
index b27d8a5fb1..85e8a53b73 100644
--- a/include/block/graph-lock.h
+++ b/include/block/graph-lock.h
@@ -135,6 +135,21 @@ void coroutine_fn bdrv_graph_co_rdunlock(void);
void bdrv_graph_rdlock_main_loop(void);
void bdrv_graph_rdunlock_main_loop(void);
+/*
+ * assert_bdrv_graph_readable:
+ * Make sure that the reader is either the main loop,
+ * or there is at least a reader helding the rdlock.
+ * In this way an incoming writer is aware of the read and waits.
+ */
+void assert_bdrv_graph_readable(void);
+
+/*
+ * assert_bdrv_graph_writable:
+ * Make sure that the writer is the main loop and has set @has_writer,
+ * so that incoming readers will pause.
+ */
+void assert_bdrv_graph_writable(void);
+
typedef struct GraphLockable { } GraphLockable;
/*
diff --git a/block.c b/block.c
index bdffadcdaa..ff53b41af3 100644
--- a/block.c
+++ b/block.c
@@ -1406,7 +1406,7 @@ static void bdrv_child_cb_attach(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
- assert_bdrv_graph_writable(bs);
+ assert_bdrv_graph_writable();
QLIST_INSERT_HEAD(&bs->children, child, next);
if (bs->drv->is_filter || (child->role & BDRV_CHILD_FILTERED)) {
/*
@@ -1452,7 +1452,7 @@ static void bdrv_child_cb_detach(BdrvChild *child)
bdrv_backing_detach(child);
}
- assert_bdrv_graph_writable(bs);
+ assert_bdrv_graph_writable();
QLIST_REMOVE(child, next);
if (child == bs->backing) {
assert(child != bs->file);
diff --git a/block/graph-lock.c b/block/graph-lock.c
index e033c6d9ac..c4d9d2c274 100644
--- a/block/graph-lock.c
+++ b/block/graph-lock.c
@@ -259,3 +259,14 @@ void bdrv_graph_rdunlock_main_loop(void)
GLOBAL_STATE_CODE();
assert(!qemu_in_coroutine());
}
+
+void assert_bdrv_graph_readable(void)
+{
+ assert(qemu_in_main_thread() || reader_count());
+}
+
+void assert_bdrv_graph_writable(void)
+{
+ assert(qemu_in_main_thread());
+ assert(qatomic_read(&has_writer));
+}
--
2.38.1
- [PULL 35/51] graph-lock: Introduce a lock to protect block graph operations, (continued)
- [PULL 35/51] graph-lock: Introduce a lock to protect block graph operations, Kevin Wolf, 2022/12/14
- [PULL 38/51] Import clang-tsa.h, Kevin Wolf, 2022/12/14
- [PULL 33/51] block/dirty-bitmap: convert coroutine-only functions to co_wrapper, Kevin Wolf, 2022/12/14
- [PULL 40/51] clang-tsa: Add macros for shared locks, Kevin Wolf, 2022/12/14
- [PULL 41/51] configure: Enable -Wthread-safety if present, Kevin Wolf, 2022/12/14
- [PULL 42/51] test-bdrv-drain: Fix incorrrect drain assumptions, Kevin Wolf, 2022/12/14
- [PULL 37/51] async: Register/unregister aiocontext in graph lock list, Kevin Wolf, 2022/12/14
- [PULL 50/51] block: use co_wrapper_mixed_bdrv_rdlock in functions taking the rdlock, Kevin Wolf, 2022/12/14
- [PULL 47/51] graph-lock: TSA annotations for lock/unlock functions, Kevin Wolf, 2022/12/14
- [PULL 48/51] Mark assert_bdrv_graph_readable/writable() GRAPH_RD/WRLOCK, Kevin Wolf, 2022/12/14
- [PULL 46/51] block: assert that graph read and writes are performed correctly,
Kevin Wolf <=
- [PULL 30/51] block-coroutine-wrapper.py: support functions without bs arg, Kevin Wolf, 2022/12/14
- [PULL 34/51] block: Factor out bdrv_drain_all_begin_nopoll(), Kevin Wolf, 2022/12/14
- [PULL 44/51] block: wrlock in bdrv_replace_child_noperm, Kevin Wolf, 2022/12/14
- [PULL 45/51] block: remove unnecessary assert_bdrv_graph_writable(), Kevin Wolf, 2022/12/14
- [PULL 39/51] clang-tsa: Add TSA_ASSERT() macro, Kevin Wolf, 2022/12/14
- [PULL 43/51] block: Fix locking in external_snapshot_prepare(), Kevin Wolf, 2022/12/14
- [PULL 49/51] block-coroutine-wrapper.py: introduce annotations that take the graph rdlock, Kevin Wolf, 2022/12/14
- [PULL 51/51] block: GRAPH_RDLOCK for functions only called by co_wrappers, Kevin Wolf, 2022/12/14
- Re: [PULL 00/51] Block layer patches, Peter Maydell, 2022/12/14