kernel/linux.git/include/linux/netdevice.h, branch linux-2.6.28.y

netpoll: fix race on poll_list resulting in garbage entry

2008-12-10T07:22:26+00:00

A few months back a race was discused between the netpoll napi service path, and the fast path through net_rx_action: http://kerneltrap.org/mailarchive/linux-netdev/2007/10/16/345470 A patch was submitted for that bug, but I think we missed a case. Consider the following scenario: INITIAL STATE CPU0 has one napi_struct A on its poll_list CPU1 is calling netpoll_send_skb and needs to call poll_napi on the same napi_struct A that CPU0 has on its list CPU0 CPU1 net_rx_action poll_napi !list_empty (returns true) locks poll_lock for A poll_one_napi napi->poll netif_rx_complete __napi_complete (removes A from poll_list) list_entry(list->next) In the above scenario, net_rx_action assumes that the per-cpu poll_list is exclusive to that cpu. netpoll of course violates that, and because the netpoll path can dequeue from the poll list, its possible for CPU0 to detect a non-empty list at the top of the while loop in net_rx_action, but have it become empty by the time it calls list_entry. Since the poll_list isn't surrounded by any other structure, the returned data from that list_entry call in this situation is garbage, and any number of crashes can result based on what exactly that garbage is. Given that its not fasible for performance reasons to place exclusive locks arround each cpus poll list to provide that mutal exclusion, I think the best solution is modify the netpoll path in such a way that we continue to guarantee that the poll_list for a cpu is in fact exclusive to that cpu. To do this I've implemented the patch below. It adds an additional bit to the state field in the napi_struct. When executing napi->poll from the netpoll_path, this bit will be set. When a driver calls netif_rx_complete, if that bit is set, it will not remove the napi_struct from the poll_list. That work will be saved for the next iteration of net_rx_action. I've tested this and it seems to work well. About the biggest drawback I can see to it is the fact that it might result in an extra loop through net_rx_action in the event that the device is actually contended for (i.e. the netpoll path actually preforms all the needed work no the device, and the call to net_rx_action winds up doing nothing, except removing the napi_struct from the poll_list. However I think this is probably a small price to pay, given that the alternative is a crash. Signed-off-by: Neil Horman Signed-off-by: David S. Miller

net: delete excess kernel-doc notation

2008-10-31T06:54:35+00:00

Remove excess kernel-doc function parameters from networking header & driver files: Warning(include/net/sock.h:946): Excess function parameter or struct member 'sk' description in 'sk_filter_release' Warning(include/linux/netdevice.h:1545): Excess function parameter or struct member 'cpu' description in 'netif_tx_lock' Warning(drivers/net/wan/z85230.c:712): Excess function parameter or struct member 'regs' description in 'z8530_interrupt' Signed-off-by: Randy Dunlap Signed-off-by: David S. Miller

net: Fix disjunct computation of netdev features

2008-10-23T08:11:29+00:00

My change commit e2a6b85247aacc52d6ba0d9b37a99b8d1a3e0d83 net: Enable TSO if supported by at least one device didn't do what was intended because the netdev_compute_features function was designed for conjunctions. So what happened was that it would simply take the TSO status of the last constituent device. This patch extends it to support both conjunctions and disjunctions under the new name of netdev_increment_features. It also adds a new function netdev_fix_features which does the sanity checking that usually occurs upon registration. This ensures that the computation doesn't result in an illegal combination since this checking is absent when the change is initiated via ethtool. The two users of netdev_compute_features have been converted. Signed-off-by: Herbert Xu Signed-off-by: David S. Miller

net: Rationalise email address: Network Specific Parts

2008-10-14T02:01:08+00:00

Clean up the various different email addresses of mine listed in the code to a single current and valid address. As Dave says his network merges for 2.6.28 are now done this seems a good point to send them in where they won't risk disrupting real changes. Signed-off-by: Alan Cox Signed-off-by: David S. Miller

dsa: add support for Trailer tagging format

2008-10-09T00:24:16+00:00

This adds support for the Trailer switch tagging format. This is another tagging that doesn't explicitly mark tagged packets with a distinct ethertype, so that we need to add a similar hack in the receive path as for the Original DSA tagging format. Signed-off-by: Lennert Buytenhek Tested-by: Byron Bradley Tested-by: Tim Ellis Signed-off-by: David S. Miller

dsa: add support for original DSA tagging format

2008-10-09T00:19:56+00:00

Most of the DSA switches currently in the field do not support the Ethertype DSA tagging format that one of the previous patches added support for, but only the original DSA tagging format. The original DSA tagging format carries the same information as the Ethertype DSA tagging format, but with the difference that it does not have an ethertype field. In other words, when receiving a packet that is tagged with an original DSA tag, there is no way of telling in eth_type_trans() that this packet is in fact a DSA-tagged packet. This patch adds a hook into eth_type_trans() which is only compiled in if support for a switch chip that doesn't support Ethertype DSA is selected, and which checks whether there is a DSA switch driver instance attached to this network device which uses the old tag format. If so, it sets the protocol field to ETH_P_DSA without looking at the packet, so that the packet ends up in the right place. Signed-off-by: Lennert Buytenhek Tested-by: Nicolas Pitre Tested-by: Peter van Valderen Tested-by: Dirk Teurlings Signed-off-by: David S. Miller

net: Distributed Switch Architecture protocol support

2008-10-09T00:15:19+00:00

Distributed Switch Architecture is a protocol for managing hardware switch chips. It consists of a set of MII management registers and commands to configure the switch, and an ethernet header format to signal which of the ports of the switch a packet was received from or is intended to be sent to. The switches that this driver supports are typically embedded in access points and routers, and a typical setup with a DSA switch looks something like this: +-----------+ +-----------+ | | RGMII | | | +-------+ +------ 1000baseT MDI ("WAN") | | | 6-port +------ 1000baseT MDI ("LAN1") | CPU | | ethernet +------ 1000baseT MDI ("LAN2") | |MIImgmt| switch +------ 1000baseT MDI ("LAN3") | +-------+ w/5 PHYs +------ 1000baseT MDI ("LAN4") | | | | +-----------+ +-----------+ The switch driver presents each port on the switch as a separate network interface to Linux, polls the switch to maintain software link state of those ports, forwards MII management interface accesses to those network interfaces (e.g. as done by ethtool) to the switch, and exposes the switch's hardware statistics counters via the appropriate Linux kernel interfaces. This initial patch supports the MII management interface register layout of the Marvell 88E6123, 88E6161 and 88E6165 switch chips, and supports the "Ethertype DSA" packet tagging format. (There is no officially registered ethertype for the Ethertype DSA packet format, so we just grab a random one. The ethertype to use is programmed into the switch, and the switch driver uses the value of ETH_P_EDSA for this, so this define can be changed at any time in the future if the one we chose is allocated to another protocol or if Ethertype DSA gets its own officially registered ethertype, and everything will continue to work.) Signed-off-by: Lennert Buytenhek Tested-by: Nicolas Pitre Tested-by: Byron Bradley Tested-by: Tim Ellis Tested-by: Peter van Valderen Tested-by: Dirk Teurlings Signed-off-by: David S. Miller

netdev: use const for some name functions

2008-09-30T09:22:14+00:00

dev_change_name and netdev_drivername should use const char on parameters that are read-only input values. The strcpy to newname is not needed since newname is not used later in function. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller

net: network device name ifalias support

2008-09-23T04:28:11+00:00

This patch add support for keeping an additional character alias associated with an network interface. This is useful for maintaining the SNMP ifAlias value which is a user defined value. Routers use this to hold information like which circuit or line it is connected to. It is just an arbitrary text label on the network device. There are two exposed interfaces with this patch, the value can be read/written either via netlink or sysfs. This could be maintained just by the snmp daemon, but it is more generally useful for other management tools, and the kernel is good place to act as an agreed upon interface to store it. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller

net: Kill plain NET_XMIT_BYPASS.

2008-08-05T06:04:08+00:00

dst_input() was doing something completely absurd, looping on skb->dst->input() if NET_XMIT_BYPASS was seen, but these functions never return such an error. And as a result plain ole' NET_XMIT_BYPASS has no more references and can be completely killed off. Signed-off-by: David S. Miller