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From: Jan Beulich <jbeulich@suse.com>
To: Julien Grall <julien@xen.org>,
	Tamas K Lengyel <tamas.k.lengyel@gmail.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Ian Jackson <iwj@xenproject.org>, Wei Liu <wl@xen.org>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Tamas K Lengyel <lengyelt@ainfosec.com>,
	Petre Ovidiu PIRCALABU <ppircalabu@bitdefender.com>,
	Alexandru Isaila <aisaila@bitdefender.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v3 5/5] evtchn: don't call Xen consumer callback with per-channel lock held
Date: Wed, 23 Dec 2020 14:41:42 +0100	[thread overview]
Message-ID: <3b339f30-57db-caf6-fd7e-84199f98546f@suse.com> (raw)
In-Reply-To: <ed5fc3e2-42b1-477a-c424-05ddf7fd3bf4@xen.org>

On 23.12.2020 14:33, Julien Grall wrote:
> On 23/12/2020 13:12, Jan Beulich wrote:
>> From the input by both of you I still can't
>> conclude whether this patch should remain as is in v4, or revert
>> back to its v2 version. Please can we get this settled so I can get
>> v4 out?
> 
> I haven't had time to investigate the rest of the VM event code to find 
> other cases where this may happen. I still think there is a bigger 
> problem in the VM event code, but the maintainer disagrees here.
> 
> At which point, I see limited reason to try to paper over in the common 
> code. So I would rather ack/merge v2 rather than v3.

Since I expect Tamas and/or the Bitdefender folks to be of the
opposite opinion, there's still no way out, at least if "rather
ack" implies a nak for v3. Personally, if this expectation of
mine is correct, I'd prefer to keep the accounting but make it
optional (as suggested in a post-commit-message remark).
That'll eliminate the overhead you appear to be concerned of,
but of course it'll further complicate the logic (albeit just
slightly).

Jan


  reply	other threads:[~2020-12-23 13:41 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-23 13:26 [PATCH v3 0/5] evtchn: (not so) recent XSAs follow-on Jan Beulich
2020-11-23 13:28 ` [PATCH v3 1/5] evtchn: drop acquiring of per-channel lock from send_guest_{global,vcpu}_virq() Jan Beulich
2020-12-02 19:03   ` Julien Grall
2020-12-03  9:46     ` Jan Beulich
2020-12-09  9:53       ` Julien Grall
2020-12-09 14:24         ` Jan Beulich
2020-11-23 13:28 ` [PATCH v3 2/5] evtchn: avoid access tearing for ->virq_to_evtchn[] accesses Jan Beulich
2020-12-02 21:14   ` Julien Grall
2020-11-23 13:28 ` [PATCH v3 3/5] evtchn: convert vIRQ lock to an r/w one Jan Beulich
2020-12-09 11:16   ` Julien Grall
2020-11-23 13:29 ` [PATCH v3 4/5] evtchn: convert domain event " Jan Beulich
2020-12-09 11:54   ` Julien Grall
2020-12-11 10:32     ` Jan Beulich
2020-12-11 10:57       ` Julien Grall
2020-12-14  9:40         ` Jan Beulich
2020-12-21 17:45           ` Julien Grall
2020-12-22  9:46             ` Jan Beulich
2020-12-23 11:22               ` Julien Grall
2020-12-23 12:57                 ` Jan Beulich
2020-12-23 13:19                   ` Julien Grall
2020-12-23 13:36                     ` Jan Beulich
2020-11-23 13:30 ` [PATCH v3 5/5] evtchn: don't call Xen consumer callback with per-channel lock held Jan Beulich
2020-11-30 10:39   ` Isaila Alexandru
2020-12-02 21:10   ` Julien Grall
2020-12-03 10:09     ` Jan Beulich
2020-12-03 14:40       ` Tamas K Lengyel
2020-12-04 11:28       ` Julien Grall
2020-12-04 11:48         ` Jan Beulich
2020-12-04 11:51           ` Julien Grall
2020-12-04 12:01             ` Jan Beulich
2020-12-04 15:09               ` Julien Grall
2020-12-07  8:02                 ` Jan Beulich
2020-12-07 17:22                   ` Julien Grall
2020-12-04 15:21         ` Tamas K Lengyel
2020-12-04 15:29           ` Julien Grall
2020-12-04 19:15             ` Tamas K Lengyel
2020-12-04 19:22               ` Julien Grall
2020-12-04 21:23                 ` Tamas K Lengyel
2020-12-07 15:28               ` Jan Beulich
2020-12-07 17:30                 ` Julien Grall
2020-12-07 17:35                   ` Tamas K Lengyel
2020-12-23 13:12                     ` Jan Beulich
2020-12-23 13:33                       ` Julien Grall
2020-12-23 13:41                         ` Jan Beulich [this message]
2020-12-23 14:44                           ` Julien Grall
2020-12-23 14:56                             ` Jan Beulich
2020-12-23 15:08                               ` Julien Grall
2020-12-23 15:15                             ` Tamas K Lengyel

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