From: David Brownell <david-b@pacbell.net>
To: linux-hotplug@vger.kernel.org
Subject: Re: udevd: serialize device chain event sequence
Date: Thu, 09 Dec 2004 03:07:39 +0000 [thread overview]
Message-ID: <200412081907.39285.david-b@pacbell.net> (raw)
In-Reply-To: <20041208231335.GA6402@vrfy.org>
On Wednesday 08 December 2004 3:13 pm, Kay Sievers wrote:
> Any objections against the serialization of the event sequence of a
> chain of devices. Currently udevd delays only events for the same
> DEVPATH.
I'm amused ... that's what the original hotplug code achieved.
Thing is, now serialization would be done in userspace, rather
than offering new and fun paths to kernel deadlock nirvana! :)
> Example of an "add" event sequence:
> /block/sda
> /block/sda/sda1
>
> With this change, we make sure, that the udev process handling /block/sda
> has finished its work (waited for all attributes, created the node) before
> we fork the udev event for /block/sda/sda1. This way the event for sda1 can
> be sure, that the node for the main device is already created (may be
> useful for disk labels).
But the "add" for the underlying hardware (maybe USB) would
not be serialized.
> The main motivation to do this is the program execution of the dev.d/
> and hotplug.d/ directory. If we don't wait for the parent event to exit,
> we can't be sure that the executed scripts are run in the right order.
Could that argument apply to the underlying hardware, too?
- Dave
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next prev parent reply other threads:[~2004-12-09 3:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-08 23:13 udevd: serialize device chain event sequence Kay Sievers
2004-12-09 3:07 ` David Brownell [this message]
2004-12-09 8:18 ` Kay Sievers
2004-12-09 10:06 ` Kay Sievers
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