2839ad58dd
This patch fixes multiple different panic scenarios occuring during hot-unload: 1. The channel is unlocked in chn_read()/chn_write() for uiomove(9) and in the meantime we enter pcm_killchans() and free it. By the time we have returned from userland and try to lock it back, the channel will have been freed. 2. The parent channel has been freed in pcm_killchans(), but at the same time, some yet-unstopped vchan's chn_read()/chn_write() calls chn_start(), which eventually calls vchan_trigger(), which references the freed parent. 3. PCM_WAIT() panics because it references a freed PCM lock. For scenarios 1 and 2, refactor pcm_killchans() to first make sure all channels have been stopped, and then proceed to free them one by one, as opposed to freeing the first free channel until all channels have been freed. This change makes the code more robust, but might introduce some performance overhead when many channels are allocated, since we continuously loop through the channel list until all of them are stopped, and then we loop one last time to free them. For scenario 3, restructure the code so that we can use destroy_dev(9) instead of destroy_dev_sched(9) in dsp_destroy_dev(). Because destroy_dev(9) blocks until all references to the device have went away, we ensure that the PCM cv and lock will be freed safely. While here, move the delete_unrhdr(9) calls to pcm_killchans() and re-order some lines. Sponsored by: The FreeBSD Foundation MFC after: 2 days Reviewed by: dev_submerge.ch Differential Revision: https://reviews.freebsd.org/D47462 |
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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 | ||
| .mailmap | ||
| 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.
For official FreeBSD bootable images, see the release 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.