#!/bin/bash
#
# Alternate sleeping and spinning on randomly selected CPUs.  The purpose
# of this script is to inflict random OS jitter on a concurrently running
# test.
#
# Usage: jitter.sh me duration [ sleepmax [ spinmax ] ]
#
# me: Random-number-generator seed salt.
# duration: Time to run in seconds.
# sleepmax: Maximum microseconds to sleep, defaults to one second.
# spinmax: Maximum microseconds to spin, defaults to one millisecond.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, you can access it online at
# http://www.gnu.org/licenses/gpl-2.0.html.
#
# Copyright (C) IBM Corporation, 2016
#
# Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

me=$(($1 * 1000))
duration=$2
sleepmax=${3-1000000}
spinmax=${4-1000}

n=1

starttime=`awk 'BEGIN { print systime(); }' < /dev/null`

while :
do
	# Check for done.
	t=`awk -v s=$starttime 'BEGIN { print systime() - s; }' < /dev/null`
	if test "$t" -gt "$duration"
	then
		exit 0;
	fi

	# Set affinity to randomly selected CPU
	cpus=`ls /sys/devices/system/cpu/*/online |
		sed -e 's,/[^/]*$,,' -e 's/^[^0-9]*//' |
		grep -v '^0*$'`
	cpumask=`awk -v cpus="$cpus" -v me=$me -v n=$n 'BEGIN {
		srand(n + me + systime());
		ncpus = split(cpus, ca);
		curcpu = ca[int(rand() * ncpus + 1)];
		mask = lshift(1, curcpu);
		if (mask + 0 <= 0)
			mask = 1;
		printf("%#x\n", mask);
	}' < /dev/null`
	n=$(($n+1))
	if ! taskset -p $cpumask $$ > /dev/null 2>&1
	then
		echo taskset failure: '"taskset -p ' $cpumask $$ '"'
		exit 1
	fi

	# Sleep a random duration
	sleeptime=`awk -v me=$me -v n=$n -v sleepmax=$sleepmax 'BEGIN {
		srand(n + me + systime());
		printf("%06d", int(rand() * sleepmax));
	}' < /dev/null`
	n=$(($n+1))
	sleep .$sleeptime

	# Spin a random duration
	limit=`awk -v me=$me -v n=$n -v spinmax=$spinmax 'BEGIN {
		srand(n + me + systime());
		printf("%06d", int(rand() * spinmax));
	}' < /dev/null`
	n=$(($n+1))
	for i in {1..$limit}
	do
		echo > /dev/null
	done
done

exit 1
 class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='42691398be08bd1fe99326911a0aa31f2c041d53'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Chuck Lever &lt;chuck.lever@oracle.com&gt;</td><td class='right'>2016-08-11 10:37:30 -0400</td></tr>
<tr><th>committer</th><td>J. Bruce Fields &lt;bfields@redhat.com&gt;</td><td class='right'>2016-08-11 15:08:39 -0400</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/?id=42691398be08bd1fe99326911a0aa31f2c041d53'>42691398be08bd1fe99326911a0aa31f2c041d53</a> (<a href='/cgit.cgi/linux/net-next.git/patch/?id=42691398be08bd1fe99326911a0aa31f2c041d53'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=42691398be08bd1fe99326911a0aa31f2c041d53'>1a0674b92269c6ed774b755189764f84c4687061</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/?id=502aa0a5be633e6558574ebcf63b65afdfbfcd7a'>502aa0a5be633e6558574ebcf63b65afdfbfcd7a</a> (<a href='/cgit.cgi/linux/net-next.git/diff/?id=42691398be08bd1fe99326911a0aa31f2c041d53&amp;id2=502aa0a5be633e6558574ebcf63b65afdfbfcd7a'>diff</a>)</td></tr></table>
<div class='commit-subject'>nfsd: Fix race between FREE_STATEID and LOCK</div><div class='commit-msg'>When running LTP's nfslock01 test, the Linux client can send a LOCK
and a FREE_STATEID request at the same time. The outcome is:

Frame 324    R OPEN stateid [2,O]

Frame 115004 C LOCK lockowner_is_new stateid [2,O] offset 672000 len 64
Frame 115008 R LOCK stateid [1,L]
Frame 115012 C WRITE stateid [0,L] offset 672000 len 64
Frame 115016 R WRITE NFS4_OK
Frame 115019 C LOCKU stateid [1,L] offset 672000 len 64
Frame 115022 R LOCKU NFS4_OK
Frame 115025 C FREE_STATEID stateid [2,L]
Frame 115026 C LOCK lockowner_is_new stateid [2,O] offset 672128 len 64
Frame 115029 R FREE_STATEID NFS4_OK
Frame 115030 R LOCK stateid [3,L]
Frame 115034 C WRITE stateid [0,L] offset 672128 len 64
Frame 115038 R WRITE NFS4ERR_BAD_STATEID

In other words, the server returns stateid L in a successful LOCK
reply, but it has already released it. Subsequent uses of stateid L
fail.

To address this, protect the generation check in nfsd4_free_stateid
with the st_mutex. This should guarantee that only one of two
outcomes occurs: either LOCK returns a fresh valid stateid, or
FREE_STATEID returns NFS4ERR_LOCKS_HELD.

Reported-by: Alexey Kodanev &lt;alexey.kodanev@oracle.com&gt;
Fix-suggested-by: Jeff Layton &lt;jlayton@redhat.com&gt;
Signed-off-by: Chuck Lever &lt;chuck.lever@oracle.com&gt;
Tested-by: Alexey Kodanev &lt;alexey.kodanev@oracle.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=42691398be08bd1fe99326911a0aa31f2c041d53'>Diffstat</a></div><table summary='diffstat' class='diffstat'>