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Re: [Qemu-devel] [PATCH 11/12] block: Use normal drain for bdrv_set_aio_
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 11/12] block: Use normal drain for bdrv_set_aio_context() |
Date: |
Tue, 19 Feb 2019 10:04:54 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 |
On 2/19/19 5:23 AM, Kevin Wolf wrote:
> Am 18.02.2019 um 21:57 hat Eric Blake geschrieben:
>> On 2/18/19 10:18 AM, Kevin Wolf wrote:
>>> Now that bdrv_set_aio_context() works inside drained sections, it can
>>> also use the real drain function instead of open coding something
>>> similar.
>>>
>>> Signed-off-by: Kevin Wolf <address@hidden>
>>> ---
>>> +/* The caller must own the AioContext lock for the old AioContext of bs,
>>> but it
>>> + * must not own the AioContext lock for new_context. */
>>
>> Is this comment still accurate, given
>>
>>> void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context)
>>> {
>>> - AioContext *ctx = bdrv_get_aio_context(bs);
>>> -
>>> - if (ctx == new_context) {
>>> + if (bdrv_get_aio_context(bs) == new_context) {
>>> return;
>>> }
>>
>> the short-circuiting when the old context is the new context?
>
> Hm, yes, old == new is an exception where you quite obviously can't have
> old locked and new unlocked at the same time.
>
> So is adding this enough?
>
> (unless new_context is the same as the current context of bs)
Works for me.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
- Re: [Qemu-devel] [PATCH 07/12] nbd: Increase bs->in_flight during AioContext switch, (continued)
[Qemu-devel] [PATCH 09/12] block: Fix AioContext switch for drained node, Kevin Wolf, 2019/02/18
[Qemu-devel] [PATCH 03/12] nbd: Restrict connection_co reentrance, Kevin Wolf, 2019/02/18
[Qemu-devel] [PATCH 11/12] block: Use normal drain for bdrv_set_aio_context(), Kevin Wolf, 2019/02/18
[Qemu-devel] [PATCH 12/12] aio-posix: Assert that aio_poll() is always called in home thread, Kevin Wolf, 2019/02/18
[Qemu-devel] [PATCH 05/12] nbd: Move nbd_read_eof() to nbd/client.c, Kevin Wolf, 2019/02/18
[Qemu-devel] [PATCH 06/12] nbd: Use low-level QIOChannel API in nbd_read_eof(), Kevin Wolf, 2019/02/18
[Qemu-devel] [PATCH 04/12] io: Make qio_channel_yield() interruptible, Kevin Wolf, 2019/02/18