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This problem only occurs on versions of FreeBSD prior to the recent CAM locking changes. (i.e. stable/9 and older versions of stable/10) This change should be a no-op for head and stable/10. If a path isn't specified, xpt_register_async() will create a fully wildcarded path and acquire a lock (the XPT lock in older versions, and via xpt_path_lock() in newer versions) to call xpt_action() for the XPT_SASYNC_CB CCB. It will then drop the lock and if the requested event includes AC_FOUND_DEVICE or AC_PATH_REGISTERED, it will get the caller up to date with any device arrivals or path registrations. The issue is that before the locking changes, each SIM lock would get acquired in turn during the EDT tree traversal process. If a path is specified for xpt_register_async(), it won't acquire and drop its own lock, but instead expects the caller to hold its own SIM lock. That works for the first part of xpt_register_async(), but causes a recursive lock acquisition once the EDT traversal happens and it comes to the SIM in question. And it isn't possible to call xpt_action() without holding a SIM lock. The locking changes fix this by using the XPT topology lock for EDT traversal, so it is no longer an issue to hold the SIM lock while calling xpt_register_async(). The solution for FreeBSD versions before the locking changes is to request notification of all device arrivals (so we pass a NULL path into xpt_register_async()) and then filter out the arrivals that are not ours. MFC After: 3 days Sponsored by: Spectra Logic Corporation |
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| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tests | ||
| 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