/*
 *  net/dccp/qpolicy.c
 *
 *  Policy-based packet dequeueing interface for DCCP.
 *
 *  Copyright (c) 2008 Tomasz Grobelny <tomasz@grobelny.oswiecenia.net>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License v2
 *  as published by the Free Software Foundation.
 */
#include "dccp.h"

/*
 *	Simple Dequeueing Policy:
 *	If tx_qlen is different from 0, enqueue up to tx_qlen elements.
 */
static void qpolicy_simple_push(struct sock *sk, struct sk_buff *skb)
{
	skb_queue_tail(&sk->sk_write_queue, skb);
}

static bool qpolicy_simple_full(struct sock *sk)
{
	return dccp_sk(sk)->dccps_tx_qlen &&
	       sk->sk_write_queue.qlen >= dccp_sk(sk)->dccps_tx_qlen;
}

static struct sk_buff *qpolicy_simple_top(struct sock *sk)
{
	return skb_peek(&sk->sk_write_queue);
}

/*
 *	Priority-based Dequeueing Policy:
 *	If tx_qlen is different from 0 and the queue has reached its upper bound
 *	of tx_qlen elements, replace older packets lowest-priority-first.
 */
static struct sk_buff *qpolicy_prio_best_skb(struct sock *sk)
{
	struct sk_buff *skb, *best = NULL;

	skb_queue_walk(&sk->sk_write_queue, skb)
		if (best == NULL || skb->priority > best->priority)
			best = skb;
	return best;
}

static struct sk_buff *qpolicy_prio_worst_skb(struct sock *sk)
{
	struct sk_buff *skb, *worst = NULL;

	skb_queue_walk(&sk->sk_write_queue, skb)
		if (worst == NULL || skb->priority < worst->priority)
			worst = skb;
	return worst;
}

static bool qpolicy_prio_full(struct sock *sk)
{
	if (qpolicy_simple_full(sk))
		dccp_qpolicy_drop(sk, qpolicy_prio_worst_skb(sk));
	return false;
}

/**
 * struct dccp_qpolicy_operations  -  TX Packet Dequeueing Interface
 * @push: add a new @skb to the write queue
 * @full: indicates that no more packets will be admitted
 * @top:  peeks at whatever the queueing policy defines as its `top'
 */
static struct dccp_qpolicy_operations {
	void		(*push)	(struct sock *sk, struct sk_buff *skb);
	bool		(*full) (struct sock *sk);
	struct sk_buff*	(*top)  (struct sock *sk);
	__be32		params;

} qpol_table[DCCPQ_POLICY_MAX] = {
	[DCCPQ_POLICY_SIMPLE] = {
		.push   = qpolicy_simple_push,
		.full   = qpolicy_simple_full,
		.top    = qpolicy_simple_top,
		.params = 0,
	},
	[DCCPQ_POLICY_PRIO] = {
		.push   = qpolicy_simple_push,
		.full   = qpolicy_prio_full,
		.top    = qpolicy_prio_best_skb,
		.params = DCCP_SCM_PRIORITY,
	},
};

/*
 *	Externally visible interface
 */
void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb)
{
	qpol_table[dccp_sk(sk)->dccps_qpolicy].push(sk, skb);
}

bool dccp_qpolicy_full(struct sock *sk)
{
	return qpol_table[dccp_sk(sk)->dccps_qpolicy].full(sk);
}

void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb)
{
	if (skb != NULL) {
		skb_unlink(skb, &sk->sk_write_queue);
		kfree_skb(skb);
	}
}

struct sk_buff *dccp_qpolicy_top(struct sock *sk)
{
	return qpol_table[dccp_sk(sk)->dccps_qpolicy].top(sk);
}

struct sk_buff *dccp_qpolicy_pop(struct sock *sk)
{
	struct sk_buff *skb = dccp_qpolicy_top(sk);

	if (skb != NULL) {
		/* Clear any skb fields that we used internally */
		skb->priority = 0;
		skb_unlink(skb, &sk->sk_write_queue);
	}
	return skb;
}

bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param)
{
	/* check if exactly one bit is set */
	if (!param || (param & (param - 1)))
		return false;
	return (qpol_table[dccp_sk(sk)->dccps_qpolicy].params & param) == param;
}
ption 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>Steven Rostedt (VMware) &lt;rostedt@goodmis.org&gt;</td><td class='right'>2017-01-30 19:27:10 -0500</td></tr>
<tr><th>committer</th><td>Steven Rostedt (VMware) &lt;rostedt@goodmis.org&gt;</td><td class='right'>2017-01-31 09:13:49 -0500</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include?id=79c6f448c8b79c321e4a1f31f98194e4f6b6cae7'>79c6f448c8b79c321e4a1f31f98194e4f6b6cae7</a> (<a href='/cgit.cgi/linux/net-next.git/patch/include?id=79c6f448c8b79c321e4a1f31f98194e4f6b6cae7'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=79c6f448c8b79c321e4a1f31f98194e4f6b6cae7'>370efda701f03cccf21e02bb1fdd3b852547d75c</a> /<a href='/cgit.cgi/linux/net-next.git/tree/include?id=79c6f448c8b79c321e4a1f31f98194e4f6b6cae7'>include</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include?id=0c744ea4f77d72b3dcebb7a8f2684633ec79be88'>0c744ea4f77d72b3dcebb7a8f2684633ec79be88</a> (<a href='/cgit.cgi/linux/net-next.git/diff/include?id=79c6f448c8b79c321e4a1f31f98194e4f6b6cae7&amp;id2=0c744ea4f77d72b3dcebb7a8f2684633ec79be88'>diff</a>)</td></tr></table>
<div class='commit-subject'>tracing: Fix hwlat kthread migration</div><div class='commit-msg'>The hwlat tracer creates a kernel thread at start of the tracer. It is
pinned to a single CPU and will move to the next CPU after each period of
running. If the user modifies the migration thread's affinity, it will not
change after that happens.

The original code created the thread at the first instance it was called,
but later was changed to destroy the thread after the tracer was finished,
and would not be created until the next instance of the tracer was
established. The code that initialized the affinity was only called on the
initial instantiation of the tracer. After that, it was not initialized, and
the previous affinity did not match the current newly created one, making
it appear that the user modified the thread's affinity when it did not, and
the thread failed to migrate again.

Cc: stable@vger.kernel.org
Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs")
Signed-off-by: Steven Rostedt (VMware) &lt;rostedt@goodmis.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=79c6f448c8b79c321e4a1f31f98194e4f6b6cae7'>Diffstat</a> (limited to 'include')</div><table summary='diffstat' class='diffstat'>