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From: Kevin Wolf <kwolf@redhat.com>
To: Sergio Lopez <slp@redhat.com>
Cc: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
	qemu-block@nongnu.org, qemu-devel@nongnu.org,
	Max Reitz <mreitz@redhat.com>, Nir Soffer <nsoffer@redhat.com>
Subject: Re: [PATCH v2 0/2] nbd/server: Quiesce server on drained section
Date: Wed, 2 Jun 2021 13:57:05 +0200	[thread overview]
Message-ID: <YLdyEblm7cVxWoBr@redhat.com> (raw)
In-Reply-To: <20210602060552.17433-1-slp@redhat.com>

Am 02.06.2021 um 08:05 hat Sergio Lopez geschrieben:
> Before switching between AioContexts we need to make sure that we're
> fully quiesced ("nb_requests == 0" for every client) when entering the
> drained section. Otherwise, coroutines may be run in the wrong context
> after the switch, leading to a number of critical issues.
> 
> To accomplish this, we add ".drained_poll" to BlockDevOps and use it
> in the NBD server, along with ".drained_being" and "drained_end", to
> coordinate the quiescing of the server while entering a drained
> section.
> 
> v2:
>  - Use a bool for the value returned by .drained_poll [Kevin]
>  - Change .drained_poll comment to reflect that the returned boolean
>    value will be true if the device is still busy, or false otherwise
>  - Drop yield_co_list and use recv_coroutine and read_yielding [Kevin]
>  - Return "true" or "false" in nbd_drained_poll [Kevin]
>  - Fix grammar in the commit message of patch 2 [Eric]

Thanks, applied to the block branch.

Kevin



      parent reply	other threads:[~2021-06-02 11:58 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-02  6:05 [PATCH v2 0/2] nbd/server: Quiesce server on drained section Sergio Lopez
2021-06-02  6:05 ` [PATCH v2 1/2] block-backend: add drained_poll Sergio Lopez
2021-06-02  8:34   ` Vladimir Sementsov-Ogievskiy
2021-06-02  6:05 ` [PATCH v2 2/2] nbd/server: Use drained block ops to quiesce the server Sergio Lopez
2021-06-02 12:06   ` Vladimir Sementsov-Ogievskiy
2021-06-02 12:44     ` Sergio Lopez
2021-06-02 12:48       ` Vladimir Sementsov-Ogievskiy
2021-06-02 11:57 ` Kevin Wolf [this message]

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