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OPNsense - FreeBSD source
ce12afaa6f
In emulated mode, the FreeBSD netmap port attempts to perform zero-copy transmission. This works as follows: the kernel ring is populated with mbuf headers to which netmap buffers are attached. When transmitting, the mbuf refcount is initialized to 2, and when the counter value has been decremented to 1 netmap infers that the driver has freed the mbuf and thus transmission is complete. This scheme does not generalize to the situation where netmap is attaching to a software interface which may transmit packets among multiple "queues", as is the case with bridge or lagg interfaces. In that case, we would be relying on backing hardware drivers to free transmitted mbufs promptly, but this isn't guaranteed; a driver may reasonably defer freeing a small number of transmitted buffers indefinitely. If such a buffer ends up at the tail of a netmap transmit ring, further transmits can end up blocked indefinitely. Fix the problem by removing the zero-copy scheme (which is also not implemented in the Linux port of netmap). Instead, the kernel ring is populated with regular mbuf clusters into which netmap buffers are copied by nm_os_generic_xmit_frame(). The refcounting scheme is preserved, and this lets us avoid allocating a fresh cluster per transmitted packet in the common case. If the transmit ring is full, a callout is used to free the "stuck" mbuf, avoiding the queue deadlock described above. Furthermore, when recycling mbuf clusters, be sure to fully reinitialize the mbuf header instead of simply re-setting M_PKTHDR. Some software interfaces, like if_vlan, may set fields in the header which should be reset before the mbuf is reused. Reviewed by: vmaffione MFC after: 1 month Sponsored by: Zenarmor Sponsored by: OPNsense Sponsored by: Klara, Inc. Differential Revision: https://reviews.freebsd.org/D38065 |
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| .cirrus-ci | ||
| .github | ||
| 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 | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitignore | ||
| CONTRIBUTING.md | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| Makefile.libcompat | ||
| Makefile.sys.inc | ||
| ObsoleteFiles.inc | ||
| README.md | ||
| RELNOTES | ||
| UPDATING | ||
FreeBSD Source:
This is the top level of the FreeBSD source directory.
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), FreeBSD handbook on building userland, and Handbook for kernels for more information, including setting make(1) variables.
For information on the CPU architectures and platforms supported by FreeBSD, see the FreeBSD website's Platforms page.
Source Roadmap:
| Directory | Description |
|---|---|
| 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 | Commands and libraries under the GNU General Public License (GPL) or Lesser General Public License (LGPL). Please see gnu/COPYING and gnu/COPYING.LIB 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 (see sys/README.md). |
| targets | Support for experimental DIRDEPS_BUILD |
| 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 FreeBSD Handbook.