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path: root/kernel/Documentation/scsi/link_power_management_policy.txt
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This parameter allows the user to set the link (interface) power management.
There are 3 possible options:

Value			Effect
----------------------------------------------------------------------------
min_power		Tell the controller to try to make the link use the
			least possible power when possible.  This may
			sacrifice some performance due to increased latency
			when coming out of lower power states.

max_performance		Generally, this means no power management.  Tell
			the controller to have performance be a priority
			over power management.

medium_power		Tell the controller to enter a lower power state
			when possible, but do not enter the lowest power
			state, thus improving latency over min_power setting.
*/ .highlight .bp { color: #003388 } /* Name.Builtin.Pseudo */ .highlight .fm { color: #0066bb; font-weight: bold } /* Name.Function.Magic */ .highlight .vc { color: #336699 } /* Name.Variable.Class */ .highlight .vg { color: #dd7700 } /* Name.Variable.Global */ .highlight .vi { color: #3333bb } /* Name.Variable.Instance */ .highlight .vm { color: #336699 } /* Name.Variable.Magic */ .highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */
/*
 *  fs/cifs/dns_resolve.c
 *
 *   Copyright (c) 2007 Igor Mammedov
 *   Author(s): Igor Mammedov (niallain@gmail.com)
 *              Steve French (sfrench@us.ibm.com)
 *              Wang Lei (wang840925@gmail.com)
 *		David Howells (dhowells@redhat.com)
 *
 *   Contains the CIFS DFS upcall routines used for hostname to
 *   IP address translation.
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library 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 Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/slab.h>
#include <linux/dns_resolver.h>
#include "dns_resolve.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"

/**
 * dns_resolve_server_name_to_ip - Resolve UNC server name to ip address.
 * @unc: UNC path specifying the server (with '/' as delimiter)
 * @ip_addr: Where to return the IP address.
 *
 * The IP address will be returned in string form, and the caller is
 * responsible for freeing it.
 *
 * Returns length of result on success, -ve on error.
 */
int
dns_resolve_server_name_to_ip(const char *unc, char **ip_addr)
{
	struct sockaddr_storage ss;
	const char *hostname, *sep;
	char *name;
	int len, rc;

	if (!ip_addr || !unc)
		return -EINVAL;

	len = strlen(unc);
	if (len < 3) {
		cifs_dbg(FYI, "%s: unc is too short: %s\n", __func__, unc);
		return -EINVAL;
	}

	/* Discount leading slashes for cifs */
	len -= 2;
	hostname = unc + 2;

	/* Search for server name delimiter */
	sep = memchr(hostname, '/', len);
	if (sep)
		len = sep - hostname;
	else
		cifs_dbg(FYI, "%s: probably server name is whole unc: %s\n",
			 __func__, unc);

	/* Try to interpret hostname as an IPv4 or IPv6 address */
	rc = cifs_convert_address((struct sockaddr *)&ss, hostname, len);
	if (rc > 0)
		goto name_is_IP_address;

	/* Perform the upcall */
	rc = dns_query(NULL, hostname, len, NULL, ip_addr, NULL);
	if (rc < 0)
		cifs_dbg(FYI, "%s: unable to resolve: %*.*s\n",
			 __func__, len, len, hostname);
	else
		cifs_dbg(FYI, "%s: resolved: %*.*s to %s\n",
			 __func__, len, len, hostname, *ip_addr);
	return rc;

name_is_IP_address:
	name = kmalloc(len + 1, GFP_KERNEL);
	if (!name)
		return -ENOMEM;
	memcpy(name, hostname, len);
	name[len] = 0;
	cifs_dbg(FYI, "%s: unc is IP, skipping dns upcall: %s\n",
		 __func__, name);
	*ip_addr = name;
	return 0;
}