drivers/staging/usbip/userspace/libsrc/vhci_driver.c: test the just-initialized value

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / scsi / fcoe / fcoe_transport.c

/*
 * Copyright(c) 2008 - 2011 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Maintained at www.Open-FCoE.org
 */

#include <linux/types.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/errno.h>
#include <linux/crc32.h>
#include <scsi/libfcoe.h>

#include "libfcoe.h"

MODULE_AUTHOR("Open-FCoE.org");
MODULE_DESCRIPTION("FIP discovery protocol and FCoE transport for FCoE HBAs");
MODULE_LICENSE("GPL v2");

static int fcoe_transport_create(const char *, struct kernel_param *);
static int fcoe_transport_destroy(const char *, struct kernel_param *);
static int fcoe_transport_show(char *buffer, const struct kernel_param *kp);
static struct fcoe_transport *fcoe_transport_lookup(struct net_device *device);
static struct fcoe_transport *fcoe_netdev_map_lookup(struct net_device *device);
static int fcoe_transport_enable(const char *, struct kernel_param *);
static int fcoe_transport_disable(const char *, struct kernel_param *);
static int libfcoe_device_notification(struct notifier_block *notifier,
                                    ulong event, void *ptr);

static LIST_HEAD(fcoe_transports);
static DEFINE_MUTEX(ft_mutex);
static LIST_HEAD(fcoe_netdevs);
static DEFINE_MUTEX(fn_mutex);

unsigned int libfcoe_debug_logging;
module_param_named(debug_logging, libfcoe_debug_logging, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(debug_logging, "a bit mask of logging levels");

module_param_call(show, NULL, fcoe_transport_show, NULL, S_IRUSR);
__MODULE_PARM_TYPE(show, "string");
MODULE_PARM_DESC(show, " Show attached FCoE transports");

module_param_call(create, fcoe_transport_create, NULL,
                  (void *)FIP_MODE_FABRIC, S_IWUSR);
__MODULE_PARM_TYPE(create, "string");
MODULE_PARM_DESC(create, " Creates fcoe instance on a ethernet interface");

module_param_call(create_vn2vn, fcoe_transport_create, NULL,
                  (void *)FIP_MODE_VN2VN, S_IWUSR);
__MODULE_PARM_TYPE(create_vn2vn, "string");
MODULE_PARM_DESC(create_vn2vn, " Creates a VN_node to VN_node FCoE instance "
                 "on an Ethernet interface");

module_param_call(destroy, fcoe_transport_destroy, NULL, NULL, S_IWUSR);
__MODULE_PARM_TYPE(destroy, "string");
MODULE_PARM_DESC(destroy, " Destroys fcoe instance on a ethernet interface");

module_param_call(enable, fcoe_transport_enable, NULL, NULL, S_IWUSR);
__MODULE_PARM_TYPE(enable, "string");
MODULE_PARM_DESC(enable, " Enables fcoe on a ethernet interface.");

module_param_call(disable, fcoe_transport_disable, NULL, NULL, S_IWUSR);
__MODULE_PARM_TYPE(disable, "string");
MODULE_PARM_DESC(disable, " Disables fcoe on a ethernet interface.");

/* notification function for packets from net device */
static struct notifier_block libfcoe_notifier = {
        .notifier_call = libfcoe_device_notification,
};

/**
 * fcoe_fc_crc() - Calculates the CRC for a given frame
 * @fp: The frame to be checksumed
 *
 * This uses crc32() routine to calculate the CRC for a frame
 *
 * Return: The 32 bit CRC value
 */
u32 fcoe_fc_crc(struct fc_frame *fp)
{
        struct sk_buff *skb = fp_skb(fp);
        struct skb_frag_struct *frag;
        unsigned char *data;
        unsigned long off, len, clen;
        u32 crc;
        unsigned i;

        crc = crc32(~0, skb->data, skb_headlen(skb));

        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
                frag = &skb_shinfo(skb)->frags[i];
                off = frag->page_offset;
                len = frag->size;
                while (len > 0) {
                        clen = min(len, PAGE_SIZE - (off & ~PAGE_MASK));
                        data = kmap_atomic(frag->page + (off >> PAGE_SHIFT),
                                           KM_SKB_DATA_SOFTIRQ);
                        crc = crc32(crc, data + (off & ~PAGE_MASK), clen);
                        kunmap_atomic(data, KM_SKB_DATA_SOFTIRQ);
                        off += clen;
                        len -= clen;
                }
        }
        return crc;
}
EXPORT_SYMBOL_GPL(fcoe_fc_crc);

/**
 * fcoe_start_io() - Start FCoE I/O
 * @skb: The packet to be transmitted
 *
 * This routine is called from the net device to start transmitting
 * FCoE packets.
 *
 * Returns: 0 for success
 */
int fcoe_start_io(struct sk_buff *skb)
{
        struct sk_buff *nskb;
        int rc;

        nskb = skb_clone(skb, GFP_ATOMIC);
        if (!nskb)
                return -ENOMEM;
        rc = dev_queue_xmit(nskb);
        if (rc != 0)
                return rc;
        kfree_skb(skb);
        return 0;
}
EXPORT_SYMBOL_GPL(fcoe_start_io);


/**
 * fcoe_clean_pending_queue() - Dequeue a skb and free it
 * @lport: The local port to dequeue a skb on
 */
void fcoe_clean_pending_queue(struct fc_lport *lport)
{
        struct fcoe_port  *port = lport_priv(lport);
        struct sk_buff *skb;

        spin_lock_bh(&port->fcoe_pending_queue.lock);
        while ((skb = __skb_dequeue(&port->fcoe_pending_queue)) != NULL) {
                spin_unlock_bh(&port->fcoe_pending_queue.lock);
                kfree_skb(skb);
                spin_lock_bh(&port->fcoe_pending_queue.lock);
        }
        spin_unlock_bh(&port->fcoe_pending_queue.lock);
}
EXPORT_SYMBOL_GPL(fcoe_clean_pending_queue);

/**
 * fcoe_check_wait_queue() - Attempt to clear the transmit backlog
 * @lport: The local port whose backlog is to be cleared
 *
 * This empties the wait_queue, dequeues the head of the wait_queue queue
 * and calls fcoe_start_io() for each packet. If all skb have been
 * transmitted it returns the qlen. If an error occurs it restores
 * wait_queue (to try again later) and returns -1.
 *
 * The wait_queue is used when the skb transmit fails. The failed skb
 * will go in the wait_queue which will be emptied by the timer function or
 * by the next skb transmit.
 */
void fcoe_check_wait_queue(struct fc_lport *lport, struct sk_buff *skb)
{
        struct fcoe_port *port = lport_priv(lport);
        int rc;

        spin_lock_bh(&port->fcoe_pending_queue.lock);

        if (skb)
                __skb_queue_tail(&port->fcoe_pending_queue, skb);

        if (port->fcoe_pending_queue_active)
                goto out;
        port->fcoe_pending_queue_active = 1;

        while (port->fcoe_pending_queue.qlen) {
                /* keep qlen > 0 until fcoe_start_io succeeds */
                port->fcoe_pending_queue.qlen++;
                skb = __skb_dequeue(&port->fcoe_pending_queue);

                spin_unlock_bh(&port->fcoe_pending_queue.lock);
                rc = fcoe_start_io(skb);
                spin_lock_bh(&port->fcoe_pending_queue.lock);

                if (rc) {
                        __skb_queue_head(&port->fcoe_pending_queue, skb);
                        /* undo temporary increment above */
                        port->fcoe_pending_queue.qlen--;
                        break;
                }
                /* undo temporary increment above */
                port->fcoe_pending_queue.qlen--;
        }

        if (port->fcoe_pending_queue.qlen < port->min_queue_depth)
                lport->qfull = 0;
        if (port->fcoe_pending_queue.qlen && !timer_pending(&port->timer))
                mod_timer(&port->timer, jiffies + 2);
        port->fcoe_pending_queue_active = 0;
out:
        if (port->fcoe_pending_queue.qlen > port->max_queue_depth)
                lport->qfull = 1;
        spin_unlock_bh(&port->fcoe_pending_queue.lock);
}
EXPORT_SYMBOL_GPL(fcoe_check_wait_queue);

/**
 * fcoe_queue_timer() - The fcoe queue timer
 * @lport: The local port
 *
 * Calls fcoe_check_wait_queue on timeout
 */
void fcoe_queue_timer(ulong lport)
{
        fcoe_check_wait_queue((struct fc_lport *)lport, NULL);
}
EXPORT_SYMBOL_GPL(fcoe_queue_timer);

/**
 * fcoe_get_paged_crc_eof() - Allocate a page to be used for the trailer CRC
 * @skb:  The packet to be transmitted
 * @tlen: The total length of the trailer
 * @fps:  The fcoe context
 *
 * This routine allocates a page for frame trailers. The page is re-used if
 * there is enough room left on it for the current trailer. If there isn't
 * enough buffer left a new page is allocated for the trailer. Reference to
 * the page from this function as well as the skbs using the page fragments
 * ensure that the page is freed at the appropriate time.
 *
 * Returns: 0 for success
 */
int fcoe_get_paged_crc_eof(struct sk_buff *skb, int tlen,
                           struct fcoe_percpu_s *fps)
{
        struct page *page;

        page = fps->crc_eof_page;
        if (!page) {
                page = alloc_page(GFP_ATOMIC);
                if (!page)
                        return -ENOMEM;

                fps->crc_eof_page = page;
                fps->crc_eof_offset = 0;
        }

        get_page(page);
        skb_fill_page_desc(skb, skb_shinfo(skb)->nr_frags, page,
                           fps->crc_eof_offset, tlen);
        skb->len += tlen;
        skb->data_len += tlen;
        skb->truesize += tlen;
        fps->crc_eof_offset += sizeof(struct fcoe_crc_eof);

        if (fps->crc_eof_offset >= PAGE_SIZE) {
                fps->crc_eof_page = NULL;
                fps->crc_eof_offset = 0;
                put_page(page);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(fcoe_get_paged_crc_eof);

/**
 * fcoe_transport_lookup - find an fcoe transport that matches a netdev
 * @netdev: The netdev to look for from all attached transports
 *
 * Returns : ptr to the fcoe transport that supports this netdev or NULL
 * if not found.
 *
 * The ft_mutex should be held when this is called
 */
static struct fcoe_transport *fcoe_transport_lookup(struct net_device *netdev)
{
        struct fcoe_transport *ft = NULL;

        list_for_each_entry(ft, &fcoe_transports, list)
                if (ft->match && ft->match(netdev))
                        return ft;
        return NULL;
}

/**
 * fcoe_transport_attach - Attaches an FCoE transport
 * @ft: The fcoe transport to be attached
 *
 * Returns : 0 for success
 */
int fcoe_transport_attach(struct fcoe_transport *ft)
{
        int rc = 0;

        mutex_lock(&ft_mutex);
        if (ft->attached) {
                LIBFCOE_TRANSPORT_DBG("transport %s already attached\n",
                                       ft->name);
                rc = -EEXIST;
                goto out_attach;
        }

        /* Add default transport to the tail */
        if (strcmp(ft->name, FCOE_TRANSPORT_DEFAULT))
                list_add(&ft->list, &fcoe_transports);
        else
                list_add_tail(&ft->list, &fcoe_transports);

        ft->attached = true;
        LIBFCOE_TRANSPORT_DBG("attaching transport %s\n", ft->name);

out_attach:
        mutex_unlock(&ft_mutex);
        return rc;
}
EXPORT_SYMBOL(fcoe_transport_attach);

/**
 * fcoe_transport_detach - Detaches an FCoE transport
 * @ft: The fcoe transport to be attached
 *
 * Returns : 0 for success
 */
int fcoe_transport_detach(struct fcoe_transport *ft)
{
        int rc = 0;
        struct fcoe_netdev_mapping *nm = NULL, *tmp;

        mutex_lock(&ft_mutex);
        if (!ft->attached) {
                LIBFCOE_TRANSPORT_DBG("transport %s already detached\n",
                        ft->name);
                rc = -ENODEV;
                goto out_attach;
        }

        /* remove netdev mapping for this transport as it is going away */
        mutex_lock(&fn_mutex);
        list_for_each_entry_safe(nm, tmp, &fcoe_netdevs, list) {
                if (nm->ft == ft) {
                        LIBFCOE_TRANSPORT_DBG("transport %s going away, "
                                "remove its netdev mapping for %s\n",
                                ft->name, nm->netdev->name);
                        list_del(&nm->list);
                        kfree(nm);
                }
        }
        mutex_unlock(&fn_mutex);

        list_del(&ft->list);
        ft->attached = false;
        LIBFCOE_TRANSPORT_DBG("detaching transport %s\n", ft->name);

out_attach:
        mutex_unlock(&ft_mutex);
        return rc;

}
EXPORT_SYMBOL(fcoe_transport_detach);

static int fcoe_transport_show(char *buffer, const struct kernel_param *kp)
{
        int i, j;
        struct fcoe_transport *ft = NULL;

        i = j = sprintf(buffer, "Attached FCoE transports:");
        mutex_lock(&ft_mutex);
        list_for_each_entry(ft, &fcoe_transports, list) {
                if (i >= PAGE_SIZE - IFNAMSIZ)
                        break;
                i += snprintf(&buffer[i], IFNAMSIZ, "%s ", ft->name);
        }
        mutex_unlock(&ft_mutex);
        if (i == j)
                i += snprintf(&buffer[i], IFNAMSIZ, "none");
        return i;
}

static int __init fcoe_transport_init(void)
{
        register_netdevice_notifier(&libfcoe_notifier);
        return 0;
}

static int __exit fcoe_transport_exit(void)
{
        struct fcoe_transport *ft;

        unregister_netdevice_notifier(&libfcoe_notifier);
        mutex_lock(&ft_mutex);
        list_for_each_entry(ft, &fcoe_transports, list)
                printk(KERN_ERR "FCoE transport %s is still attached!\n",
                      ft->name);
        mutex_unlock(&ft_mutex);
        return 0;
}


static int fcoe_add_netdev_mapping(struct net_device *netdev,
                                        struct fcoe_transport *ft)
{
        struct fcoe_netdev_mapping *nm;

        nm = kmalloc(sizeof(*nm), GFP_KERNEL);
        if (!nm) {
                printk(KERN_ERR "Unable to allocate netdev_mapping");
                return -ENOMEM;
        }

        nm->netdev = netdev;
        nm->ft = ft;

        mutex_lock(&fn_mutex);
        list_add(&nm->list, &fcoe_netdevs);
        mutex_unlock(&fn_mutex);
        return 0;
}


static void fcoe_del_netdev_mapping(struct net_device *netdev)
{
        struct fcoe_netdev_mapping *nm = NULL, *tmp;

        mutex_lock(&fn_mutex);
        list_for_each_entry_safe(nm, tmp, &fcoe_netdevs, list) {
                if (nm->netdev == netdev) {
                        list_del(&nm->list);
                        kfree(nm);
                        mutex_unlock(&fn_mutex);
                        return;
                }
        }
        mutex_unlock(&fn_mutex);
}


/**
 * fcoe_netdev_map_lookup - find the fcoe transport that matches the netdev on which
 * it was created
 *
 * Returns : ptr to the fcoe transport that supports this netdev or NULL
 * if not found.
 *
 * The ft_mutex should be held when this is called
 */
static struct fcoe_transport *fcoe_netdev_map_lookup(struct net_device *netdev)
{
        struct fcoe_transport *ft = NULL;
        struct fcoe_netdev_mapping *nm;

        mutex_lock(&fn_mutex);
        list_for_each_entry(nm, &fcoe_netdevs, list) {
                if (netdev == nm->netdev) {
                        ft = nm->ft;
                        mutex_unlock(&fn_mutex);
                        return ft;
                }
        }

        mutex_unlock(&fn_mutex);
        return NULL;
}

/**
 * fcoe_if_to_netdev() - Parse a name buffer to get a net device
 * @buffer: The name of the net device
 *
 * Returns: NULL or a ptr to net_device
 */
static struct net_device *fcoe_if_to_netdev(const char *buffer)
{
        char *cp;
        char ifname[IFNAMSIZ + 2];

        if (buffer) {
                strlcpy(ifname, buffer, IFNAMSIZ);
                cp = ifname + strlen(ifname);
                while (--cp >= ifname && *cp == '\n')
                        *cp = '\0';
                return dev_get_by_name(&init_net, ifname);
        }
        return NULL;
}

/**
 * libfcoe_device_notification() - Handler for net device events
 * @notifier: The context of the notification
 * @event:    The type of event
 * @ptr:      The net device that the event was on
 *
 * This function is called by the Ethernet driver in case of link change event.
 *
 * Returns: 0 for success
 */
static int libfcoe_device_notification(struct notifier_block *notifier,
                                    ulong event, void *ptr)
{
        struct net_device *netdev = ptr;

        switch (event) {
        case NETDEV_UNREGISTER:
                printk(KERN_ERR "libfcoe_device_notification: NETDEV_UNREGISTER %s\n",
                                netdev->name);
                fcoe_del_netdev_mapping(netdev);
                break;
        }
        return NOTIFY_OK;
}


/**
 * fcoe_transport_create() - Create a fcoe interface
 * @buffer: The name of the Ethernet interface to create on
 * @kp:     The associated kernel param
 *
 * Called from sysfs. This holds the ft_mutex while calling the
 * registered fcoe transport's create function.
 *
 * Returns: 0 for success
 */
static int fcoe_transport_create(const char *buffer, struct kernel_param *kp)
{
        int rc = -ENODEV;
        struct net_device *netdev = NULL;
        struct fcoe_transport *ft = NULL;
        enum fip_state fip_mode = (enum fip_state)(long)kp->arg;

        mutex_lock(&ft_mutex);

        netdev = fcoe_if_to_netdev(buffer);
        if (!netdev) {
                LIBFCOE_TRANSPORT_DBG("Invalid device %s.\n", buffer);
                goto out_nodev;
        }

        ft = fcoe_netdev_map_lookup(netdev);
        if (ft) {
                LIBFCOE_TRANSPORT_DBG("transport %s already has existing "
                                      "FCoE instance on %s.\n",
                                      ft->name, netdev->name);
                rc = -EEXIST;
                goto out_putdev;
        }

        ft = fcoe_transport_lookup(netdev);
        if (!ft) {
                LIBFCOE_TRANSPORT_DBG("no FCoE transport found for %s.\n",
                                      netdev->name);
                goto out_putdev;
        }

        rc = fcoe_add_netdev_mapping(netdev, ft);
        if (rc) {
                LIBFCOE_TRANSPORT_DBG("failed to add new netdev mapping "
                                      "for FCoE transport %s for %s.\n",
                                      ft->name, netdev->name);
                goto out_putdev;
        }

        /* pass to transport create */
        rc = ft->create ? ft->create(netdev, fip_mode) : -ENODEV;
        if (rc)
                fcoe_del_netdev_mapping(netdev);

        LIBFCOE_TRANSPORT_DBG("transport %s %s to create fcoe on %s.\n",
                              ft->name, (rc) ? "failed" : "succeeded",
                              netdev->name);

out_putdev:
        dev_put(netdev);
out_nodev:
        mutex_unlock(&ft_mutex);
        return rc;
}

/**
 * fcoe_transport_destroy() - Destroy a FCoE interface
 * @buffer: The name of the Ethernet interface to be destroyed
 * @kp:     The associated kernel parameter
 *
 * Called from sysfs. This holds the ft_mutex while calling the
 * registered fcoe transport's destroy function.
 *
 * Returns: 0 for success
 */
static int fcoe_transport_destroy(const char *buffer, struct kernel_param *kp)
{
        int rc = -ENODEV;
        struct net_device *netdev = NULL;
        struct fcoe_transport *ft = NULL;

        mutex_lock(&ft_mutex);

        netdev = fcoe_if_to_netdev(buffer);
        if (!netdev) {
                LIBFCOE_TRANSPORT_DBG("invalid device %s.\n", buffer);
                goto out_nodev;
        }

        ft = fcoe_netdev_map_lookup(netdev);
        if (!ft) {
                LIBFCOE_TRANSPORT_DBG("no FCoE transport found for %s.\n",
                                      netdev->name);
                goto out_putdev;
        }

        /* pass to transport destroy */
        rc = ft->destroy ? ft->destroy(netdev) : -ENODEV;
        fcoe_del_netdev_mapping(netdev);
        LIBFCOE_TRANSPORT_DBG("transport %s %s to destroy fcoe on %s.\n",
                              ft->name, (rc) ? "failed" : "succeeded",
                              netdev->name);

out_putdev:
        dev_put(netdev);
out_nodev:
        mutex_unlock(&ft_mutex);
        return rc;
}

/**
 * fcoe_transport_disable() - Disables a FCoE interface
 * @buffer: The name of the Ethernet interface to be disabled
 * @kp:     The associated kernel parameter
 *
 * Called from sysfs.
 *
 * Returns: 0 for success
 */
static int fcoe_transport_disable(const char *buffer, struct kernel_param *kp)
{
        int rc = -ENODEV;
        struct net_device *netdev = NULL;
        struct fcoe_transport *ft = NULL;

        mutex_lock(&ft_mutex);

        netdev = fcoe_if_to_netdev(buffer);
        if (!netdev)
                goto out_nodev;

        ft = fcoe_netdev_map_lookup(netdev);
        if (!ft)
                goto out_putdev;

        rc = ft->disable ? ft->disable(netdev) : -ENODEV;

out_putdev:
        dev_put(netdev);
out_nodev:
        mutex_unlock(&ft_mutex);

        if (rc == -ERESTARTSYS)
                return restart_syscall();
        else
                return rc;
}

/**
 * fcoe_transport_enable() - Enables a FCoE interface
 * @buffer: The name of the Ethernet interface to be enabled
 * @kp:     The associated kernel parameter
 *
 * Called from sysfs.
 *
 * Returns: 0 for success
 */
static int fcoe_transport_enable(const char *buffer, struct kernel_param *kp)
{
        int rc = -ENODEV;
        struct net_device *netdev = NULL;
        struct fcoe_transport *ft = NULL;

        mutex_lock(&ft_mutex);

        netdev = fcoe_if_to_netdev(buffer);
        if (!netdev)
                goto out_nodev;

        ft = fcoe_netdev_map_lookup(netdev);
        if (!ft)
                goto out_putdev;

        rc = ft->enable ? ft->enable(netdev) : -ENODEV;

out_putdev:
        dev_put(netdev);
out_nodev:
        mutex_unlock(&ft_mutex);
        return rc;
}

/**
 * libfcoe_init() - Initialization routine for libfcoe.ko
 */
static int __init libfcoe_init(void)
{
        fcoe_transport_init();

        return 0;
}
module_init(libfcoe_init);

/**
 * libfcoe_exit() - Tear down libfcoe.ko
 */
static void __exit libfcoe_exit(void)
{
        fcoe_transport_exit();
}
module_exit(libfcoe_exit);