Robert Watson 83b3d58d05 In the current world order, each socket has two mutexes: a mutex
that protects socket and receive socket buffer state, and a second
mutex to protect send socket buffer state.  In some places, the
mutex shared between the socket and receive socket buffer will be
acquired twice, once by each layer, resulting in some
inconsistency, but providing the abstraction benefit of being able
to more easily separate the two mutexes in the future if desired.

When transitioning a socket to the SS_ISDISCONNECTING or
SS_ISDISCONNECTED states, grab the socket/receive socket buffer lock
once rather than grabbing it as the socket lock, modifying socket
state, then grabbing a second time as the receive lock in order to
modify the socket buffer state to indicate no further data can be
read.  This change is believed to close a race between the change in
socket state and the change in socket buffer state, which for a
remotely initiated close on a UNIX domain socket, resulted in
soreceive() returning ENOTCONN rather than an EOF condition.

A similar race still exists in the case of send, however, and is
harder to fix as the socket and send socket buffer mutexes are not
the same, and we would like to avoid holding combinations of socket
mutexes over sb_upcall until we've finished clarifying the locking
protocol for upcalls.

This change has the side affect of reducing the number of mutex
operations to initiate disconnect or perform disconnect on a
socket by two.

PR:		78824
Rerported by:	Marc Olzheim <marcolz@stack.nl>
MFC after:	2 weeks
2005-05-27 17:16:43 +00:00
2005-05-23 10:52:07 +00:00
2005-02-25 06:04:12 +00:00
2005-01-01 07:29:20 +00:00

This is the top level of the FreeBSD source directory.  This file
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For copyright information, please see the file COPYRIGHT in this
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Building a kernel is a somewhat more involved process, documentation
for which can be found at:
   http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html
And in the config(8) man page.
Note: If you want to build and install the kernel with the
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The sample kernel configuration files reside in the sys/<arch>/conf
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Source Roadmap:
---------------
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contrib		Packages contributed by 3rd parties.

crypto		Cryptography stuff (see crypto/README).

etc		Template files for /etc.

games		Amusements.

gnu		Various commands and libraries under the GNU Public License.
		Please see gnu/COPYING* for more information.

include		System include files.

kerberos5	Kerberos5 (Heimdal) package.

lib		System libraries.

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release		Release building Makefile & associated tools.

sbin		System commands.

secure		Cryptographic libraries and commands.

share		Shared resources.

sys		Kernel sources.

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usr.sbin	System administration commands.


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