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[PULL v2 02/10] block: Avoid processing BDS twice in bdrv_set_aio_contex
From: |
Kevin Wolf |
Subject: |
[PULL v2 02/10] block: Avoid processing BDS twice in bdrv_set_aio_context_ignore() |
Date: |
Tue, 2 Feb 2021 17:28:26 +0100 |
From: Sergio Lopez <slp@redhat.com>
Some graphs may contain an indirect reference to the first BDS in the
chain that can be reached while walking it bottom->up from one its
children.
Doubling-processing of a BDS is especially problematic for the
aio_notifiers, as they might attempt to work on both the old and the
new AIO contexts.
To avoid this problem, add every child and parent to the ignore list
before actually processing them.
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Sergio Lopez <slp@redhat.com>
Message-Id: <20210201125032.44713-2-slp@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block.c | 34 +++++++++++++++++++++++++++-------
1 file changed, 27 insertions(+), 7 deletions(-)
diff --git a/block.c b/block.c
index 91a66d4f3e..5c428e1595 100644
--- a/block.c
+++ b/block.c
@@ -6439,7 +6439,10 @@ void bdrv_set_aio_context_ignore(BlockDriverState *bs,
AioContext *new_context, GSList **ignore)
{
AioContext *old_context = bdrv_get_aio_context(bs);
- BdrvChild *child;
+ GSList *children_to_process = NULL;
+ GSList *parents_to_process = NULL;
+ GSList *entry;
+ BdrvChild *child, *parent;
g_assert(qemu_get_current_aio_context() == qemu_get_aio_context());
@@ -6454,16 +6457,33 @@ void bdrv_set_aio_context_ignore(BlockDriverState *bs,
continue;
}
*ignore = g_slist_prepend(*ignore, child);
- bdrv_set_aio_context_ignore(child->bs, new_context, ignore);
+ children_to_process = g_slist_prepend(children_to_process, child);
}
- QLIST_FOREACH(child, &bs->parents, next_parent) {
- if (g_slist_find(*ignore, child)) {
+
+ QLIST_FOREACH(parent, &bs->parents, next_parent) {
+ if (g_slist_find(*ignore, parent)) {
continue;
}
- assert(child->klass->set_aio_ctx);
- *ignore = g_slist_prepend(*ignore, child);
- child->klass->set_aio_ctx(child, new_context, ignore);
+ *ignore = g_slist_prepend(*ignore, parent);
+ parents_to_process = g_slist_prepend(parents_to_process, parent);
+ }
+
+ for (entry = children_to_process;
+ entry != NULL;
+ entry = g_slist_next(entry)) {
+ child = entry->data;
+ bdrv_set_aio_context_ignore(child->bs, new_context, ignore);
+ }
+ g_slist_free(children_to_process);
+
+ for (entry = parents_to_process;
+ entry != NULL;
+ entry = g_slist_next(entry)) {
+ parent = entry->data;
+ assert(parent->klass->set_aio_ctx);
+ parent->klass->set_aio_ctx(parent, new_context, ignore);
}
+ g_slist_free(parents_to_process);
bdrv_detach_aio_context(bs);
--
2.29.2
- [PULL v2 00/10] Block layer patches, Kevin Wolf, 2021/02/02
- [PULL v2 01/10] MAINTAINERS: Add Vladimir as co-maintainer for Block Jobs, Kevin Wolf, 2021/02/02
- [PULL v2 03/10] block: move blk_exp_close_all() to qemu_cleanup(), Kevin Wolf, 2021/02/02
- [PULL v2 02/10] block: Avoid processing BDS twice in bdrv_set_aio_context_ignore(),
Kevin Wolf <=
- [PULL v2 05/10] iotests: Revert emulator selection to old behaviour, Kevin Wolf, 2021/02/02
- [PULL v2 04/10] iotests/297: pylint: ignore too many statements, Kevin Wolf, 2021/02/02
- [PULL v2 07/10] iotests: Fix -makecheck output, Kevin Wolf, 2021/02/02
- [PULL v2 09/10] block/nvme: Trace NVMe spec version supported by the controller, Kevin Wolf, 2021/02/02
- [PULL v2 08/10] block/nvme: Properly display doorbell stride length in trace event, Kevin Wolf, 2021/02/02
- [PULL v2 06/10] iotests: check: return 1 on failure, Kevin Wolf, 2021/02/02
- [PULL v2 10/10] block: Fix VM size column width in bdrv_snapshot_dump(), Kevin Wolf, 2021/02/02
- Re: [PULL v2 00/10] Block layer patches, Peter Maydell, 2021/02/02