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Re: [PATCH v6 09/33] block: introduce assert_bdrv_graph_writable
From: |
Kevin Wolf |
Subject: |
Re: [PATCH v6 09/33] block: introduce assert_bdrv_graph_writable |
Date: |
Mon, 7 Feb 2022 18:14:37 +0100 |
Am 21.01.2022 um 18:05 hat Emanuele Giuseppe Esposito geschrieben:
> 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>
> diff --git a/block/io.c b/block/io.c
> index cb095deeec..3be08cad29 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -734,6 +734,17 @@ void bdrv_drain_all(void)
> bdrv_drain_all_end();
> }
>
> +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());
> +}
This looks like a trivial function that could easily be static inline.
Kevin
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