freebsd kernel with SKQ
5ed480f8c9
The cause of "Duplicate mbuf free panic" is in the programming error of hme_load_txmbuf(). The code path of the panic is the following. 1. Due to unknown reason DMA engine was freezed. So TX descritors of HME become full and the last failed attempt to transmit a packet had set its associated mbuf address to hme_txdesc structure. Also the failed packet is requeued into interface queue structure in order to retrasmit it when there are more available TX descritors. 2. Since DMA engine was freezed, if_timer starts to decrement its counter. When if_timer expires it tries to reset HME. During the reset phase, hme_meminit() is called and it frees all associated mbuf with descriptors. The last failed mbuf is also freed here. 3. After HME reset completed, HME starts to retransmit packets by dequeing the first packet in interface queue.(Note! the packet was already freed in hme_meminit()!) 4. When a TX completion interrupt is posted by the HME, driver tries to free the successfylly transmitted mbuf. Since the mbuf was freed in step2, now we get "Duplicate mbuf free panic". However, the real cause is in DMA engine freeze. Since no fatal errors reported via interrupts, there might be other cause of the freeze. I tried hard to understand the cause of DMA engine freeze but couldn't find any clues. It seems that the freeze happens under very high network loads(e.g. 7.5-8.0 MB/s TX speed). Though this fix is not enough to eliminate DMA engine freeze it's better than panic. Reported by: jhb via sparc64 ML |
||
|---|---|---|
| bin | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| COPYRIGHT | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| 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 ``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. 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. 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