From: Mike Waychison <Michael.Waychison@Sun.COM>
To: linux-hotplug@vger.kernel.org
Subject: Re: [PATCH] convert udevsend/udevd to DGRAM and single-threaded
Date: Sat, 07 Feb 2004 02:04:29 +0000 [thread overview]
Message-ID: <402447AD.50805@sun.com> (raw)
In-Reply-To: <40232F58.3040404@sympatico.ca>
Patrick Mansfield wrote:
>On Fri, Feb 06, 2004 at 05:22:23PM -0500, Chris Friesen wrote:
>
>
>>Patrick Mansfield wrote:
>>
>>
>>
>>>>On Fri, Feb 06, 2004 at 01:08:24AM -0500, Chris Friesen wrote:
>>>>
>>>>
>>>>- ssock = socket(AF_LOCAL, SOCK_STREAM, 0);
>>>>+ ssock = socket(AF_LOCAL, SOCK_DGRAM, 0);
>>>>
>>>>
>>>How are dropped packets handled?
>>>
>>>
>
>
>
>>If udevd is not present, then the udevsend creates it. Otherwise, it blocks
>>until the message is placed in udevd's buffer. No problem there.
>>
>>If udevd crashes after the message was placed in its rx buffer but before
>>handling it, then you have a problem, but this problem exists for any protocol
>>and to solve it you need to have an ack message sent back to udevsend *after*
>>the udev has run and returned for that message.
>>
>>
>
>I mean, SOCK_DGRAM is an unreliable transport, so what happens if the
>transport drops packets? It might be unlikely, especially for the AF_LOCAL,
>but it is possible.
>
>I don't see any ack or retransmit code in udevsend.
>
>
>
SOCK_DGRAM is a reliable transport under AF_UNIX / AF_LOCAL. From unix(7):
Valid types are SOCK_STREAM for a stream oriented socket and
SOCK_DGRAM
for a datagram oriented socket that preserves message
boundaries. Unix
sockets are always reliable and don't reorder datagrams.
--
Mike Waychison
Sun Microsystems, Inc.
1 (650) 352-5299 voice
1 (416) 202-8336 voice
mailto: Michael.Waychison@Sun.COM
http://www.sun.com
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next prev parent reply other threads:[~2004-02-07 2:04 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-06 6:08 [PATCH] convert udevsend/udevd to DGRAM and single-threaded Chris Friesen
2004-02-06 11:27 ` Kay Sievers
2004-02-06 16:03 ` Robert Love
2004-02-06 16:58 ` Patrick Mansfield
2004-02-06 22:21 ` Greg KH
2004-02-06 22:22 ` Chris Friesen
2004-02-07 1:24 ` Patrick Mansfield
2004-02-07 2:04 ` Mike Waychison [this message]
2004-02-07 7:06 ` Chris Friesen
2004-02-07 7:32 ` Patrick Mansfield
2004-02-07 10:06 ` Kay Sievers
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