/*
 * netsniff-ng - the packet sniffing beast
 * Copyright 2012 Markus Amend <markus@netsniff-ng.org>, Deutsche Flugsicherung GmbH
 * Subject to the GPL, version 2.
 *
 * IPv6 Fragmentation Header described in RFC2460
 */

#include <stdio.h>
#include <stdint.h>
#include <netinet/in.h>    /* for ntohs() */

#include "proto.h"
#include "dissector_eth.h"
#include "built_in.h"
#include "pkt_buff.h"

struct fragmhdr {
	uint8_t h_fragm_next_header;
	uint8_t h_fragm_reserved;
	uint16_t h_fragm_off_res_M;	
	uint32_t h_fragm_identification;
} __packed;

static void fragm(struct pkt_buff *pkt)
{
	uint16_t off_res_M;
	struct fragmhdr *fragm_ops;

	fragm_ops = (struct fragmhdr *) pkt_pull(pkt, sizeof(*fragm_ops));
	if (fragm_ops == NULL)
		return;

	off_res_M = ntohs(fragm_ops->h_fragm_off_res_M);
	
	tprintf("\t [ Fragment ");
	tprintf("NextHdr (%u), ", fragm_ops->h_fragm_next_header);
	tprintf("Reserved (%u), ", fragm_ops->h_fragm_reserved);
	tprintf("Offset (%u), ", off_res_M >> 3);
	tprintf("Res (%u), ", (off_res_M >> 1) & 0x3);
	tprintf("M flag (%u), ", off_res_M & 0x1);
	tprintf("Identification (%u)",
		ntohl(fragm_ops->h_fragm_identification));
	tprintf(" ]\n");

	pkt_set_dissector(pkt, &eth_lay3, fragm_ops->h_fragm_next_header);
}

static void fragm_less(struct pkt_buff *pkt)
{
	uint16_t off_res_M;
	struct fragmhdr *fragm_ops;

	fragm_ops = (struct fragmhdr *) pkt_pull(pkt, sizeof(*fragm_ops));
	if (fragm_ops == NULL)
		return;

	off_res_M = ntohs(fragm_ops->h_fragm_off_res_M);

	tprintf(" FragmOffs %u", off_res_M >> 3);

	pkt_set_dissector(pkt, &eth_lay3, fragm_ops->h_fragm_next_header);
}

struct protocol ipv6_fragm_ops = {
	.key = 0x2C,
	.print_full = fragm,
	.print_less = fragm_less,
};
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/commit/?id=5aff60a191e579ae00ae5ca6ce16c13b687bc8a3'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/kernel?id=5aff60a191e579ae00ae5ca6ce16c13b687bc8a3'>kernel</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='5aff60a191e579ae00ae5ca6ce16c13b687bc8a3'/><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>Pan Xinhui &lt;xinhui.pan@linux.vnet.ibm.com&gt;</td><td class='right'>2016-11-02 05:08:29 -0400</td></tr>
<tr><th>committer</th><td>Ingo Molnar &lt;mingo@kernel.org&gt;</td><td class='right'>2016-11-22 12:48:10 +0100</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/kernel?id=5aff60a191e579ae00ae5ca6ce16c13b687bc8a3'>5aff60a191e579ae00ae5ca6ce16c13b687bc8a3</a> (<a href='/cgit.cgi/linux/net-next.git/patch/kernel?id=5aff60a191e579ae00ae5ca6ce16c13b687bc8a3'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=5aff60a191e579ae00ae5ca6ce16c13b687bc8a3'>1dfe75f4697e367a178044b043ad2ca8dc250f3a</a> /<a href='/cgit.cgi/linux/net-next.git/tree/kernel?id=5aff60a191e579ae00ae5ca6ce16c13b687bc8a3'>kernel</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/kernel?id=3dd3e0ce7989b645eee0174b17f5095e187c7f28'>3dd3e0ce7989b645eee0174b17f5095e187c7f28</a> (<a href='/cgit.cgi/linux/net-next.git/diff/kernel?id=5aff60a191e579ae00ae5ca6ce16c13b687bc8a3&amp;id2=3dd3e0ce7989b645eee0174b17f5095e187c7f28'>diff</a>)</td></tr></table>
<div class='commit-subject'>locking/osq: Break out of spin-wait busy waiting loop for a preempted vCPU in osq_lock()</div><div class='commit-msg'>An over-committed guest with more vCPUs than pCPUs has a heavy overload
in osq_lock().

This is because if vCPU-A holds the osq lock and yields out, vCPU-B ends
up waiting for per_cpu node-&gt;locked to be set. IOW, vCPU-B waits for
vCPU-A to run and unlock the osq lock.

Use the new vcpu_is_preempted(cpu) interface to detect if a vCPU is
currently running or not, and break out of the spin-loop if so.

test case:

 $ perf record -a perf bench sched messaging -g 400 -p &amp;&amp; perf report

 before patch:
 18.09%  sched-messaging  [kernel.vmlinux]  [k] osq_lock
 12.28%  sched-messaging  [kernel.vmlinux]  [k] rwsem_spin_on_owner
  5.27%  sched-messaging  [kernel.vmlinux]  [k] mutex_unlock
  3.89%  sched-messaging  [kernel.vmlinux]  [k] wait_consider_task
  3.64%  sched-messaging  [kernel.vmlinux]  [k] _raw_write_lock_irq
  3.41%  sched-messaging  [kernel.vmlinux]  [k] mutex_spin_on_owner.is
  2.49%  sched-messaging  [kernel.vmlinux]  [k] system_call

 after patch:
 20.68%  sched-messaging  [kernel.vmlinux]  [k] mutex_spin_on_owner
  8.45%  sched-messaging  [kernel.vmlinux]  [k] mutex_unlock
  4.12%  sched-messaging  [kernel.vmlinux]  [k] system_call
  3.01%  sched-messaging  [kernel.vmlinux]  [k] system_call_common
  2.83%  sched-messaging  [kernel.vmlinux]  [k] copypage_power7
  2.64%  sched-messaging  [kernel.vmlinux]  [k] rwsem_spin_on_owner
  2.00%  sched-messaging  [kernel.vmlinux]  [k] osq_lock

Suggested-by: Boqun Feng &lt;boqun.feng@gmail.com&gt;
Tested-by: Juergen Gross &lt;jgross@suse.com&gt;
Signed-off-by: Pan Xinhui &lt;xinhui.pan@linux.vnet.ibm.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Acked-by: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Acked-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: benh@kernel.crashing.org
Cc: bsingharora@gmail.com
Cc: dave@stgolabs.net
Cc: kernellwp@gmail.com
Cc: konrad.wilk@oracle.com
Cc: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au
Cc: paulmck@linux.vnet.ibm.com
Cc: paulus@samba.org
Cc: rkrcmar@redhat.com
Cc: virtualization@lists.linux-foundation.org
Cc: will.deacon@arm.com
Cc: xen-devel-request@lists.xenproject.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1478077718-37424-3-git-send-email-xinhui.pan@linux.vnet.ibm.com
[ Translated to English. ]
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=5aff60a191e579ae00ae5ca6ce16c13b687bc8a3'>Diffstat</a> (limited to 'kernel')</div><table summary='diffstat' class='diffstat'>