From: Paolo Bonzini <pbonzini@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>, qemu-block@nongnu.org
Cc: mreitz@redhat.com, famz@redhat.com, slp@redhat.com,
jsnow@redhat.com, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v2 08/17] block: Add missing locking in bdrv_co_drain_bh_cb()
Date: Thu, 13 Sep 2018 17:17:42 +0200 [thread overview]
Message-ID: <98c140fc-2d06-29a5-404e-0c5fe7a85629@redhat.com> (raw)
In-Reply-To: <20180913125217.23173-9-kwolf@redhat.com>
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
next prev parent reply other threads:[~2018-09-13 15:17 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-13 12:52 [Qemu-devel] [PATCH v2 00/17] Fix some jobs/drain/aio_poll related hangs Kevin Wolf
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 01/17] job: Fix missing locking due to mismerge Kevin Wolf
2018-09-13 13:56 ` Max Reitz
2018-09-13 17:38 ` John Snow
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 02/17] blockjob: Wake up BDS when job becomes idle Kevin Wolf
2018-09-13 14:31 ` Max Reitz
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 03/17] aio-wait: Increase num_waiters even in home thread Kevin Wolf
2018-09-13 15:11 ` Paolo Bonzini
2018-09-13 17:21 ` Kevin Wolf
2018-09-14 15:14 ` Paolo Bonzini
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 04/17] test-bdrv-drain: Drain with block jobs in an I/O thread Kevin Wolf
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 05/17] test-blockjob: Acquire AioContext around job_cancel_sync() Kevin Wolf
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 06/17] job: Use AIO_WAIT_WHILE() in job_finish_sync() Kevin Wolf
2018-09-13 14:45 ` Max Reitz
2018-09-13 15:15 ` Paolo Bonzini
2018-09-13 17:39 ` Kevin Wolf
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 07/17] test-bdrv-drain: Test AIO_WAIT_WHILE() in completion callback Kevin Wolf
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 08/17] block: Add missing locking in bdrv_co_drain_bh_cb() Kevin Wolf
2018-09-13 14:58 ` Max Reitz
2018-09-13 15:17 ` Paolo Bonzini [this message]
2018-09-13 17:36 ` Kevin Wolf
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 09/17] block-backend: Add .drained_poll callback Kevin Wolf
2018-09-13 15:01 ` Max Reitz
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 10/17] block-backend: Fix potential double blk_delete() Kevin Wolf
2018-09-13 15:19 ` Paolo Bonzini
2018-09-13 19:50 ` Max Reitz
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 11/17] block-backend: Decrease in_flight only after callback Kevin Wolf
2018-09-13 15:10 ` Paolo Bonzini
2018-09-13 16:59 ` Kevin Wolf
2018-09-14 7:47 ` Fam Zheng
2018-09-14 15:12 ` Paolo Bonzini
2018-09-14 17:14 ` Kevin Wolf
2018-09-14 17:38 ` Paolo Bonzini
2018-09-13 20:50 ` Max Reitz
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 12/17] mirror: Fix potential use-after-free in active commit Kevin Wolf
2018-09-13 20:55 ` Max Reitz
2018-09-13 21:43 ` Max Reitz
2018-09-14 16:25 ` Kevin Wolf
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 13/17] blockjob: Lie better in child_job_drained_poll() Kevin Wolf
2018-09-13 21:52 ` Max Reitz
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 14/17] block: Remove aio_poll() in bdrv_drain_poll variants Kevin Wolf
2018-09-13 21:55 ` Max Reitz
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 15/17] test-bdrv-drain: Test nested poll in bdrv_drain_poll_top_level() Kevin Wolf
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 16/17] job: Avoid deadlocks in job_completed_txn_abort() Kevin Wolf
2018-09-13 22:01 ` Max Reitz
2018-09-13 12:52 ` [Qemu-devel] [PATCH v2 17/17] test-bdrv-drain: AIO_WAIT_WHILE() in job .commit/.abort Kevin Wolf
2018-09-13 22:05 ` Max Reitz
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