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Re: [Qemu-block] [PATCH v2 08/17] block: Add missing locking in bdrv_co_
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-block] [PATCH v2 08/17] block: Add missing locking in bdrv_co_drain_bh_cb() |
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Date: |
Thu, 13 Sep 2018 17:17:42 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
On 13/09/2018 14:52, Kevin Wolf wrote:
> bdrv_do_drained_begin/end() assume that they are called with the
> AioContext lock of bs held. If we call drain functions from a coroutine
> with the AioContext lock held, we yield and schedule a BH to move out of
> coroutine context. This means that the lock for the home context of the
> coroutine is released and must be re-acquired in the bottom half.
What exactly needs the lock, is it bdrv_drain_invoke?
Would it make sense to always do release/acquire in bdrv_drain, and
always do acquire/release in bdrv_drain_invoke? (Conditional locking is
tricky...).
Thanks,
Paolo
- Re: [Qemu-block] [PATCH v2 03/17] aio-wait: Increase num_waiters even in home thread, (continued)
[Qemu-block] [PATCH v2 04/17] test-bdrv-drain: Drain with block jobs in an I/O thread, Kevin Wolf, 2018/09/13
[Qemu-block] [PATCH v2 05/17] test-blockjob: Acquire AioContext around job_cancel_sync(), Kevin Wolf, 2018/09/13
[Qemu-block] [PATCH v2 06/17] job: Use AIO_WAIT_WHILE() in job_finish_sync(), Kevin Wolf, 2018/09/13
[Qemu-block] [PATCH v2 08/17] block: Add missing locking in bdrv_co_drain_bh_cb(), Kevin Wolf, 2018/09/13
[Qemu-block] [PATCH v2 09/17] block-backend: Add .drained_poll callback, Kevin Wolf, 2018/09/13
[Qemu-block] [PATCH v2 07/17] test-bdrv-drain: Test AIO_WAIT_WHILE() in completion callback, Kevin Wolf, 2018/09/13
[Qemu-block] [PATCH v2 10/17] block-backend: Fix potential double blk_delete(), Kevin Wolf, 2018/09/13
[Qemu-block] [PATCH v2 11/17] block-backend: Decrease in_flight only after callback, Kevin Wolf, 2018/09/13