8f43a81524
The existing AF_UNIX socket garbage collector destroys any socket which may potentially be in a cycle, as indicated by its file reference count being equal to its enqueue count. However, this can produce false positives for in-flight sockets which aren't part of a cycle but are part of one or more SCM_RIGHTS mssages and which have been closed on the sending side. If the garbage collector happens to run at exactly the wrong time, destruction of these sockets will render them unusable on the receiving side, such that no previously-written data may be read. This change rewrites the garbage collector to precisely detect cycles: 1. The existing check of msgcount==f_count is still used to determine whether the socket is potentially in a cycle. 2. The socket is now placed on a local "dead list", which is used to reduce iteration time (and therefore contention on the global unp_link_rwlock). 3. The first pass through the dead list removes each potentially-dead socket's outgoing references from the graph of potentially-dead sockets, using a gc-specific copy of the original reference count. 4. The second series of passes through the dead list removes from the list any socket whose remaining gc refcount is non-zero, as this indicates the socket is actually accessible outside of any possible cycle. Iteration is repeated until no further sockets are removed from the dead list. 5. Sockets remaining in the dead list are destroyed as before. PR: 227285 Submitted by: jan.kokemueller@gmail.com (prior version) Reviewed by: markj Differential Revision: https://reviews.freebsd.org/D23142 |
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| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| stand | ||
| sys | ||
| targets | ||
| tests | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| .arcconfig | ||
| .arclint | ||
| .cirrus.yml | ||
| .clang-format | ||
| .gitattributes | ||
| .gitignore | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| Makefile.libcompat | ||
| Makefile.sys.inc | ||
| ObsoleteFiles.inc | ||
| README | ||
| README.md | ||
| RELNOTES | ||
| UPDATING | ||
FreeBSD Source:
This is the top level of the FreeBSD source directory. This file
was last revised on:
FreeBSD
FreeBSD is an operating system used to power modern servers, desktops, and embedded platforms. A large community has continually developed it for more than thirty years. Its advanced networking, security, and storage features have made FreeBSD the platform of choice for many of the busiest web sites and most pervasive embedded networking and storage devices.
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. See build(7), config(8), https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html, and https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html for more information, including setting make(1) variables.
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.
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.
stand Boot loader sources.
sys Kernel sources.
sys/<arch>/conf Kernel configuration files. GENERIC is the configuration
used in release builds. NOTES contains documentation of
all possible entries.
tests Regression tests which can be run by Kyua. See tests/README
for additional information.
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:
https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/current-stable.html