FreeBSD src
Before this change state creating sequence was: 1) lock wire key hash 2) link state's wire key 3) unlock wire key hash 4) lock stack key hash 5) link state's stack key 6) unlock stack key hash 7) lock ID hash 8) link into ID hash 9) unlock ID hash What could happen here is that other thread finds the state via key hash lookup after 6), locks ID hash and does some processing of the state. When the thread creating state unblocks, it finds the state it was inserting already non-virgin. Now we perform proper interlocking between key hash locks and ID hash lock: 1) lock wire & stack hashes 2) link state's keys 3) lock ID hash 4) unlock wire & stack hashes 5) link into ID hash 6) unlock ID hash To achieve that, the following hacking was performed in pf_state_key_attach(): - Key hash mutex is marked with MTX_DUPOK. - To avoid deadlock on 2 key hash mutexes, we lock them in order determined by their address value. - pf_state_key_attach() had a magic to reuse a > FIN_WAIT_2 state. It unlinked the conflicting state synchronously. In theory this could require locking a third key hash, which we can't do now. Now we do not remove the state immediately, instead we leave this task to the purge thread. To avoid conflicts in a short period before state is purged, we push to the very end of the TAILQ. - On success, before dropping key hash locks, pf_state_key_attach() locks ID hash and returns. Tested by: Ian FREISLICH <ianf clue.co.za> |
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bin | ||
cddl | ||
contrib | ||
crypto | ||
etc | ||
games | ||
gnu | ||
include | ||
kerberos5 | ||
lib | ||
libexec | ||
release | ||
rescue | ||
sbin | ||
secure | ||
share | ||
sys | ||
tools | ||
usr.bin | ||
usr.sbin | ||
COPYRIGHT | ||
LOCKS | ||
MAINTAINERS | ||
Makefile | ||
Makefile.inc1 | ||
ObsoleteFiles.inc | ||
README | ||
UPDATING |
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``world'' target should only be used in cases where the source tree has not changed from the currently running version. See: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html for more information, including setting make(1) variables. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. 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 ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/user commands. cddl Various commands and libraries under the Common Development and Distribution License. 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. libexec System daemons. release Release building Makefile & associated tools. rescue Build system for statically linked /rescue utilities. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html