Konstantin Belousov aef68c961a When delivering a signal with default disposition to the thread,
tdsigwakeup() increases the priority of the low-priority threads, to
give them a chance to be terminated timely.  Also, kernel allows user
to signal kernel processes.  The combined effect is that signalling
idle process bump a priority of the selected delivery thread, which
starts eating CPU.

Check for the delivery thread be an idle thread and do not raise its
priority then.

The signal delivery to the kernel threads must be opt-in feature.
Kernel thread should explicitely declare the ability to handle signals
directed to it.  E.g., nfsd threads check for signal as an indication
of exit request.

Most threads do not handle signals at all, and queuing the signal to
them causes odd side-effects.  Most innocent consequence is the memory
leak due to queued ksiginfo, which is never deleted from the sigqueue.
Code to prevent even queuing signals to the kernel threads is trivial,
but it requires careful examination of each call to kproc/kthread
creation to decide should the signalling be allowed.  The commit is a
stop-gap measure which fixes the immediate case for now.

PR:	200493
Reported and tested by:	trasz
Discussed with:	trasz, emaste
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-05-29 16:26:08 +00:00
2015-05-27 10:08:31 +00:00
2015-05-25 01:18:46 +00:00
2015-05-27 14:28:19 +00:00
2015-04-02 22:42:23 +00:00
2015-05-06 15:29:11 +00:00
2015-05-27 19:49:33 +00:00
2015-05-29 10:07:20 +00:00
2015-04-20 20:33:22 +00:00
2014-12-31 10:00:43 +00:00
2015-04-19 07:16:44 +00:00

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.  See build(7)
and 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.  See build(7), config(8),
and http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html
for more information.

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 kernel configuration files reside in the sys/<arch>/conf
sub-directory.  GENERIC is the default configuration used in release builds.
NOTES contains entries and documentation for all possible
devices, not just those commonly used.


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.

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:

  http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html
Description
freebsd kernel with SKQ
Readme 2 GiB
Languages
C 63.3%
C++ 23.3%
Roff 5.1%
Shell 2.9%
Makefile 1.5%
Other 3.4%