From: Kay Sievers <kay.sievers@vrfy.org>
To: linux-hotplug@vger.kernel.org
Subject: Re: udev synchronization problems
Date: Thu, 15 Sep 2005 15:34:47 +0000 [thread overview]
Message-ID: <20050915153447.GA7187@vrfy.org> (raw)
In-Reply-To: <4328D34C.7070008@jcwren.com>
On Wed, Sep 14, 2005 at 09:50:04PM -0400, J.C. Wren wrote:
> Forgive me if this has been addressed before. I did some googling
> for answers, but either there are none, or more likely, I am not using
> the correct search terms for useful results.
>
> I have a script to create compact flash cards for an application.
> It worked well until I switched from devfs to udev.
>
> The script is pretty basic. sfdisk, mke2fs, tune2fs, mount, cp,
> umount. I run into errors where sfdisk completes, then mke2fs complains
> that /dev/hde1 (hde is the PCMCIA CF card) doesn't exist. Or sometimes
> it gets past that, and tune2fs complains /dev/hde1 doesn't exist.
>
> As near as I can tell, it's because udevd doesn't react fast enough
> (from my scripts perspective) and present /dev/hde1 once it's been
> created. So I tried a few things. I put a loop in the script waiting
> for /dev/hde1 to become present. Didn't fix it. Added some 'sleep 1'
> commands. Didn't fix it. Tried a while loop that waited for /dev/hde1
> to become present in /proc/partitions. Didn't fix it. However, running
> these commands by hand almost always succeed.
>
> Is there some reliable way to determine that /dev/hde1 is *really*
> there, and ready for action?
>
> I've tried 2.6.12-gentoo-r10, 2.6.13 (vanilla), both against udev
> 068 and 069.
>
> I've been through the udev utilities, didn't see anything that
> looked like it was what I neeed. Is there a handy command that makes
> sure things are flushed and updated before the next action can take place?
>
> I'll cheerfully take a solution, or go back to Google if someone can
> tell me what sort of search terms would be relevant.
I don't see why a while loop wouldn't work. Please run "udevmonitor" while
yoy run your script and post the output here.
I expect fdisk writes the partitiontanble and triggers a reread with
a ioctl, which will create the hotplug events for the partition devices.
You have to wait for the nodes to appear.
Kay
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next prev parent reply other threads:[~2005-09-15 15:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-15 1:50 udev synchronization problems J.C. Wren
2005-09-15 15:34 ` Kay Sievers [this message]
2005-09-19 16:51 ` J.C. Wren
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