Revision 712f3147aee0fbbbbed2da20b21b272c5505125e authored by Linus Torvalds on 13 May 2011, 23:16:41 UTC, committed by Linus Torvalds on 14 May 2011, 17:23:44 UTC
When a register_framebuffer() call results in us removing old conflicting framebuffers, the new registration_lock doesn't protect that situation. And we can't just add the same locking to the function, because these functions call each other: register_framebuffer() calls remove_conflicting_framebuffers, which in turn calls unregister_framebuffer for any conflicting entry. In order to fix it, this just creates wrapper functions around all three functions and makes the versions that actually do the work be called "do_xxx()", leaving just the wrapper that gets the lock and calls the worker function. So the rule becomes simply that "do_xxxx()" has to be called with the lock held, and now do_register_framebuffer() can just call do_remove_conflicting_framebuffers(), and that in turn can call _do_unregister_framebuffer(), and there is no deadlock, and we can hold the registration lock over the whole sequence, fixing the races. It also makes error cases simpler, and fixes one situation where we would return from unregister_framebuffer() without releasing the lock, pointed out by Bruno Prémont. Tested-by: Bruno Prémont <bonbons@linux-vserver.org> Tested-by: Anca Emanuel <anca.emanuel@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent c47747f
br_device.c
/*
* Device handling code
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <buytenh@gnu.org>
*
* 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.
*/
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/netpoll.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/list.h>
#include <linux/netfilter_bridge.h>
#include <asm/uaccess.h>
#include "br_private.h"
/* net device transmit always called with BH disabled */
netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct net_bridge *br = netdev_priv(dev);
const unsigned char *dest = skb->data;
struct net_bridge_fdb_entry *dst;
struct net_bridge_mdb_entry *mdst;
struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);
#ifdef CONFIG_BRIDGE_NETFILTER
if (skb->nf_bridge && (skb->nf_bridge->mask & BRNF_BRIDGED_DNAT)) {
br_nf_pre_routing_finish_bridge_slow(skb);
return NETDEV_TX_OK;
}
#endif
u64_stats_update_begin(&brstats->syncp);
brstats->tx_packets++;
brstats->tx_bytes += skb->len;
u64_stats_update_end(&brstats->syncp);
BR_INPUT_SKB_CB(skb)->brdev = dev;
skb_reset_mac_header(skb);
skb_pull(skb, ETH_HLEN);
rcu_read_lock();
if (is_multicast_ether_addr(dest)) {
if (unlikely(netpoll_tx_running(dev))) {
br_flood_deliver(br, skb);
goto out;
}
if (br_multicast_rcv(br, NULL, skb)) {
kfree_skb(skb);
goto out;
}
mdst = br_mdb_get(br, skb);
if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb))
br_multicast_deliver(mdst, skb);
else
br_flood_deliver(br, skb);
} else if ((dst = __br_fdb_get(br, dest)) != NULL)
br_deliver(dst->dst, skb);
else
br_flood_deliver(br, skb);
out:
rcu_read_unlock();
return NETDEV_TX_OK;
}
static int br_dev_open(struct net_device *dev)
{
struct net_bridge *br = netdev_priv(dev);
netif_carrier_off(dev);
br_features_recompute(br);
netif_start_queue(dev);
br_stp_enable_bridge(br);
br_multicast_open(br);
return 0;
}
static void br_dev_set_multicast_list(struct net_device *dev)
{
}
static int br_dev_stop(struct net_device *dev)
{
struct net_bridge *br = netdev_priv(dev);
netif_carrier_off(dev);
br_stp_disable_bridge(br);
br_multicast_stop(br);
netif_stop_queue(dev);
return 0;
}
static struct rtnl_link_stats64 *br_get_stats64(struct net_device *dev,
struct rtnl_link_stats64 *stats)
{
struct net_bridge *br = netdev_priv(dev);
struct br_cpu_netstats tmp, sum = { 0 };
unsigned int cpu;
for_each_possible_cpu(cpu) {
unsigned int start;
const struct br_cpu_netstats *bstats
= per_cpu_ptr(br->stats, cpu);
do {
start = u64_stats_fetch_begin(&bstats->syncp);
memcpy(&tmp, bstats, sizeof(tmp));
} while (u64_stats_fetch_retry(&bstats->syncp, start));
sum.tx_bytes += tmp.tx_bytes;
sum.tx_packets += tmp.tx_packets;
sum.rx_bytes += tmp.rx_bytes;
sum.rx_packets += tmp.rx_packets;
}
stats->tx_bytes = sum.tx_bytes;
stats->tx_packets = sum.tx_packets;
stats->rx_bytes = sum.rx_bytes;
stats->rx_packets = sum.rx_packets;
return stats;
}
static int br_change_mtu(struct net_device *dev, int new_mtu)
{
struct net_bridge *br = netdev_priv(dev);
if (new_mtu < 68 || new_mtu > br_min_mtu(br))
return -EINVAL;
dev->mtu = new_mtu;
#ifdef CONFIG_BRIDGE_NETFILTER
/* remember the MTU in the rtable for PMTU */
dst_metric_set(&br->fake_rtable.dst, RTAX_MTU, new_mtu);
#endif
return 0;
}
/* Allow setting mac address to any valid ethernet address. */
static int br_set_mac_address(struct net_device *dev, void *p)
{
struct net_bridge *br = netdev_priv(dev);
struct sockaddr *addr = p;
if (!is_valid_ether_addr(addr->sa_data))
return -EINVAL;
spin_lock_bh(&br->lock);
memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
br_stp_change_bridge_id(br, addr->sa_data);
br->flags |= BR_SET_MAC_ADDR;
spin_unlock_bh(&br->lock);
return 0;
}
static void br_getinfo(struct net_device *dev, struct ethtool_drvinfo *info)
{
strcpy(info->driver, "bridge");
strcpy(info->version, BR_VERSION);
strcpy(info->fw_version, "N/A");
strcpy(info->bus_info, "N/A");
}
static int br_set_sg(struct net_device *dev, u32 data)
{
struct net_bridge *br = netdev_priv(dev);
if (data)
br->feature_mask |= NETIF_F_SG;
else
br->feature_mask &= ~NETIF_F_SG;
br_features_recompute(br);
return 0;
}
static int br_set_tso(struct net_device *dev, u32 data)
{
struct net_bridge *br = netdev_priv(dev);
if (data)
br->feature_mask |= NETIF_F_TSO;
else
br->feature_mask &= ~NETIF_F_TSO;
br_features_recompute(br);
return 0;
}
static int br_set_tx_csum(struct net_device *dev, u32 data)
{
struct net_bridge *br = netdev_priv(dev);
if (data)
br->feature_mask |= NETIF_F_NO_CSUM;
else
br->feature_mask &= ~NETIF_F_ALL_CSUM;
br_features_recompute(br);
return 0;
}
static int br_set_flags(struct net_device *netdev, u32 data)
{
return ethtool_op_set_flags(netdev, data, ETH_FLAG_TXVLAN);
}
#ifdef CONFIG_NET_POLL_CONTROLLER
static void br_poll_controller(struct net_device *br_dev)
{
}
static void br_netpoll_cleanup(struct net_device *dev)
{
struct net_bridge *br = netdev_priv(dev);
struct net_bridge_port *p, *n;
list_for_each_entry_safe(p, n, &br->port_list, list) {
br_netpoll_disable(p);
}
}
static int br_netpoll_setup(struct net_device *dev, struct netpoll_info *ni)
{
struct net_bridge *br = netdev_priv(dev);
struct net_bridge_port *p, *n;
int err = 0;
list_for_each_entry_safe(p, n, &br->port_list, list) {
if (!p->dev)
continue;
err = br_netpoll_enable(p);
if (err)
goto fail;
}
out:
return err;
fail:
br_netpoll_cleanup(dev);
goto out;
}
int br_netpoll_enable(struct net_bridge_port *p)
{
struct netpoll *np;
int err = 0;
np = kzalloc(sizeof(*p->np), GFP_KERNEL);
err = -ENOMEM;
if (!np)
goto out;
np->dev = p->dev;
err = __netpoll_setup(np);
if (err) {
kfree(np);
goto out;
}
p->np = np;
out:
return err;
}
void br_netpoll_disable(struct net_bridge_port *p)
{
struct netpoll *np = p->np;
if (!np)
return;
p->np = NULL;
/* Wait for transmitting packets to finish before freeing. */
synchronize_rcu_bh();
__netpoll_cleanup(np);
kfree(np);
}
#endif
static int br_add_slave(struct net_device *dev, struct net_device *slave_dev)
{
struct net_bridge *br = netdev_priv(dev);
return br_add_if(br, slave_dev);
}
static int br_del_slave(struct net_device *dev, struct net_device *slave_dev)
{
struct net_bridge *br = netdev_priv(dev);
return br_del_if(br, slave_dev);
}
static const struct ethtool_ops br_ethtool_ops = {
.get_drvinfo = br_getinfo,
.get_link = ethtool_op_get_link,
.get_tx_csum = ethtool_op_get_tx_csum,
.set_tx_csum = br_set_tx_csum,
.get_sg = ethtool_op_get_sg,
.set_sg = br_set_sg,
.get_tso = ethtool_op_get_tso,
.set_tso = br_set_tso,
.get_ufo = ethtool_op_get_ufo,
.set_ufo = ethtool_op_set_ufo,
.get_flags = ethtool_op_get_flags,
.set_flags = br_set_flags,
};
static const struct net_device_ops br_netdev_ops = {
.ndo_open = br_dev_open,
.ndo_stop = br_dev_stop,
.ndo_start_xmit = br_dev_xmit,
.ndo_get_stats64 = br_get_stats64,
.ndo_set_mac_address = br_set_mac_address,
.ndo_set_multicast_list = br_dev_set_multicast_list,
.ndo_change_mtu = br_change_mtu,
.ndo_do_ioctl = br_dev_ioctl,
#ifdef CONFIG_NET_POLL_CONTROLLER
.ndo_netpoll_setup = br_netpoll_setup,
.ndo_netpoll_cleanup = br_netpoll_cleanup,
.ndo_poll_controller = br_poll_controller,
#endif
.ndo_add_slave = br_add_slave,
.ndo_del_slave = br_del_slave,
};
static void br_dev_free(struct net_device *dev)
{
struct net_bridge *br = netdev_priv(dev);
free_percpu(br->stats);
free_netdev(dev);
}
void br_dev_setup(struct net_device *dev)
{
random_ether_addr(dev->dev_addr);
ether_setup(dev);
dev->netdev_ops = &br_netdev_ops;
dev->destructor = br_dev_free;
SET_ETHTOOL_OPS(dev, &br_ethtool_ops);
dev->tx_queue_len = 0;
dev->priv_flags = IFF_EBRIDGE;
dev->features = NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_HIGHDMA |
NETIF_F_GSO_MASK | NETIF_F_NO_CSUM | NETIF_F_LLTX |
NETIF_F_NETNS_LOCAL | NETIF_F_GSO | NETIF_F_HW_VLAN_TX;
}
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