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From: "Jürgen Groß" <jgross@suse.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>,
	"Paul Durrant" <pdurrant@amazon.com>
Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
	Stefano Stabellini <sstabellini@kernel.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [Xen-devel] [PATCH 2/4] xenbus: limit when state is forced to closed
Date: Mon, 9 Dec 2019 12:55:01 +0100	[thread overview]
Message-ID: <b8a138ad-5770-65fa-f368-f7b4063702fa@suse.com> (raw)
In-Reply-To: <20191209113926.GS980@Air-de-Roger>

On 09.12.19 12:39, Roger Pau Monné wrote:
> On Thu, Dec 05, 2019 at 02:01:21PM +0000, Paul Durrant wrote:
>> Only force state to closed in the case when the toolstack may need to
>> clean up. This can be detected by checking whether the state in xenstore
>> has been set to closing prior to device removal.
> 
> I'm not sure I see the point of this, I would expect that a failure to
> probe or the removal of the device would leave the xenbus state as
> closed, which is consistent with the actual driver state.
> 
> Can you explain what's the benefit of leaving a device without a
> driver in such unknown state?

And more concerning: did you check that no frontend/backend is
relying on the closed state to be visible without closing having been
set before?


Juergen


WARNING: multiple messages have this Message-ID (diff)
From: "Jürgen Groß" <jgross@suse.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>,
	"Paul Durrant" <pdurrant@amazon.com>
Cc: xen-devel@lists.xenproject.org,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [Xen-devel] [PATCH 2/4] xenbus: limit when state is forced to closed
Date: Mon, 9 Dec 2019 12:55:01 +0100	[thread overview]
Message-ID: <b8a138ad-5770-65fa-f368-f7b4063702fa@suse.com> (raw)
In-Reply-To: <20191209113926.GS980@Air-de-Roger>

On 09.12.19 12:39, Roger Pau Monné wrote:
> On Thu, Dec 05, 2019 at 02:01:21PM +0000, Paul Durrant wrote:
>> Only force state to closed in the case when the toolstack may need to
>> clean up. This can be detected by checking whether the state in xenstore
>> has been set to closing prior to device removal.
> 
> I'm not sure I see the point of this, I would expect that a failure to
> probe or the removal of the device would leave the xenbus state as
> closed, which is consistent with the actual driver state.
> 
> Can you explain what's the benefit of leaving a device without a
> driver in such unknown state?

And more concerning: did you check that no frontend/backend is
relying on the closed state to be visible without closing having been
set before?


Juergen


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Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

  reply	other threads:[~2019-12-09 11:55 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-05 14:01 [PATCH 0/4] xen-blkback: support live update Paul Durrant
2019-12-05 14:01 ` [Xen-devel] " Paul Durrant
2019-12-05 14:01 ` [PATCH 1/4] xenbus: move xenbus_dev_shutdown() into frontend code Paul Durrant
2019-12-05 14:01   ` [Xen-devel] " Paul Durrant
2019-12-09 11:33   ` Jürgen Groß
2019-12-09 11:33     ` [Xen-devel] " Jürgen Groß
2019-12-09 11:55     ` Durrant, Paul
2019-12-09 11:55       ` [Xen-devel] " Durrant, Paul
2019-12-09 11:57       ` Jürgen Groß
2019-12-09 11:57         ` [Xen-devel] " Jürgen Groß
2019-12-05 14:01 ` [PATCH 2/4] xenbus: limit when state is forced to closed Paul Durrant
2019-12-05 14:01   ` [Xen-devel] " Paul Durrant
2019-12-09 11:39   ` Roger Pau Monné
2019-12-09 11:39     ` Roger Pau Monné
2019-12-09 11:55     ` Jürgen Groß [this message]
2019-12-09 11:55       ` Jürgen Groß
2019-12-09 12:03       ` Durrant, Paul
2019-12-09 12:03         ` Durrant, Paul
2019-12-09 12:08         ` Jürgen Groß
2019-12-09 12:08           ` Jürgen Groß
2019-12-09 12:19           ` Durrant, Paul
2019-12-09 12:19             ` Durrant, Paul
2019-12-09 13:38             ` Jürgen Groß
2019-12-09 13:38               ` Jürgen Groß
2019-12-09 14:06               ` Durrant, Paul
2019-12-09 14:06                 ` Durrant, Paul
2019-12-09 14:09                 ` Jürgen Groß
2019-12-09 14:09                   ` Jürgen Groß
2019-12-09 14:23                   ` Durrant, Paul
2019-12-09 14:23                     ` Durrant, Paul
2019-12-09 14:41                     ` Jürgen Groß
2019-12-09 14:41                       ` Jürgen Groß
2019-12-09 14:43                       ` Durrant, Paul
2019-12-09 14:43                         ` Durrant, Paul
2019-12-09 12:01     ` Durrant, Paul
2019-12-09 12:01       ` Durrant, Paul
2019-12-09 12:25       ` Roger Pau Monné
2019-12-09 12:25         ` Roger Pau Monné
2019-12-09 12:40         ` Durrant, Paul
2019-12-09 12:40           ` Durrant, Paul
2019-12-09 14:28           ` Roger Pau Monné
2019-12-09 14:28             ` Roger Pau Monné
2019-12-09 14:41             ` Durrant, Paul
2019-12-09 14:41               ` Durrant, Paul
2019-12-09 15:13               ` Roger Pau Monné
2019-12-09 15:13                 ` Roger Pau Monné
2019-12-09 16:26                 ` Durrant, Paul
2019-12-09 16:26                   ` Durrant, Paul
2019-12-09 17:17                   ` Roger Pau Monné
2019-12-09 17:17                     ` Roger Pau Monné
2019-12-09 17:23                     ` Durrant, Paul
2019-12-09 17:23                       ` Durrant, Paul
2019-12-05 14:01 ` [PATCH 3/4] xen/interface: don't discard pending work in FRONT/BACK_RING_ATTACH Paul Durrant
2019-12-05 14:01   ` [Xen-devel] " Paul Durrant
2019-12-09 11:41   ` Roger Pau Monné
2019-12-09 11:41     ` Roger Pau Monné
2019-12-09 11:52     ` Jürgen Groß
2019-12-09 11:52       ` Jürgen Groß
2019-12-09 12:50       ` Durrant, Paul
2019-12-09 12:50         ` Durrant, Paul
2019-12-09 13:55   ` Jürgen Groß
2019-12-09 13:55     ` [Xen-devel] " Jürgen Groß
2019-12-09 16:38     ` Durrant, Paul
2019-12-09 16:38       ` [Xen-devel] " Durrant, Paul
2019-12-10 11:42       ` Jürgen Groß
2019-12-10 11:42         ` [Xen-devel] " Jürgen Groß
2019-12-05 14:01 ` [PATCH 4/4] xen-blkback: support dynamic unbind/bind Paul Durrant
2019-12-05 14:01   ` [Xen-devel] " Paul Durrant
2019-12-09 12:17   ` Roger Pau Monné
2019-12-09 12:17     ` [Xen-devel] " Roger Pau Monné
2019-12-09 12:24     ` Durrant, Paul
2019-12-09 12:24       ` [Xen-devel] " Durrant, Paul
2019-12-09 13:57   ` Jürgen Groß
2019-12-09 13:57     ` [Xen-devel] " Jürgen Groß
2019-12-09 14:01     ` Durrant, Paul
2019-12-09 14:01       ` [Xen-devel] " Durrant, Paul

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