From: Markus Pargmann <mpa@pengutronix.de>
To: Wouter Verhelst <w@uter.be>
Cc: nbd-general <nbd-general@lists.sourceforge.net>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] nbd: Issue a uevent when disconnecting
Date: Fri, 05 Feb 2016 10:03:41 +0100 [thread overview]
Message-ID: <5247002.OuBHJMaBYj@adelgunde> (raw)
In-Reply-To: <20160202152700.GA7562@grep.be>
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Hi Wouter,
On Tuesday, February 02, 2016 04:27:00 PM Wouter Verhelst wrote:
> There already is a uevent by default when closing a device upon connect
> of the device. However, the same isn't true on disconnect.
>
> This makes it hard for userspace to keep track of whether a device is
> connected, since we are notified when the connection is created, but not
> when it is removed again.
>
> Explicitly issue a "change" uevent to remedy.
>
> [v2: incorporate feedback from udev maintainer and make sure that we
> issue a uevent upon connect as well as disconnect, rather than connect
> only]
The systemd people had the same feedback. Basically the device is not
marked as ready until a uevent is received. My idea was to use the size
property consistently. If the device is connected the size is correctly
changed and a uevent is created. On disconnect the size is set to 0 with
another uevent.
Does this work for you as well? I will send the patch as reply.
Thanks,
Markus
>
> Signed-off-by: Wouter Verhelst <w@uter.be>
> ---
> drivers/block/nbd.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index e4c5cc1..04d9563 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -417,6 +417,8 @@ static int nbd_thread_recv(struct nbd_device *nbd)
> spin_unlock_irqrestore(&nbd->tasks_lock, flags);
>
> ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
> + kobject_uevent(&disk_to_dev(nbd->disk)->kobj, KOBJ_CHANGE);
> +
> if (ret) {
> dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
>
> @@ -438,6 +440,7 @@ static int nbd_thread_recv(struct nbd_device *nbd)
> }
>
> device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
> + kobject_uevent(&disk_to_dev(nbd->disk)->kobj, KOBJ_CHANGE);
>
> spin_lock_irqsave(&nbd->tasks_lock, flags);
> nbd->task_recv = NULL;
>
--
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next prev parent reply other threads:[~2016-02-05 9:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-23 16:23 [PATCH] Issue a uevent when disconnecting Wouter Verhelst
2016-02-02 15:27 ` [PATCH v2] nbd: " Wouter Verhelst
2016-02-05 9:03 ` Markus Pargmann [this message]
2016-02-05 9:42 ` Wouter Verhelst
2016-02-12 14:49 ` Markus Pargmann
2016-02-05 9:04 ` [PATCH] nbd: Create size change events for userspace Markus Pargmann
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