linux-toradex.git/include/linux/netlink.h, branch tegra-10.7.1

genetlink: fix netns vs. netlink table locking (2)

2009-09-24T22:44:05+00:00

Similar to commit d136f1bd366fdb7e747ca7e0218171e7a00a98a5,
there's a bug when unregistering a generic netlink family,
which is caught by the might_sleep() added in that commit:

    BUG: sleeping function called from invalid context at net/netlink/af_netlink.c:183
    in_atomic(): 1, irqs_disabled(): 0, pid: 1510, name: rmmod
    2 locks held by rmmod/1510:
     #0:  (genl_mutex){+.+.+.}, at: [] genl_unregister_family+0x2b/0x130
     #1:  (rcu_read_lock){.+.+..}, at: [] __genl_unregister_mc_group+0x1c/0x120
    Pid: 1510, comm: rmmod Not tainted 2.6.31-wl #444
    Call Trace:
     [] __might_sleep+0x119/0x150
     [] netlink_table_grab+0x21/0x100
     [] netlink_clear_multicast_users+0x23/0x60
     [] __genl_unregister_mc_group+0x71/0x120
     [] genl_unregister_family+0x56/0x130
     [] nl80211_exit+0x15/0x20 [cfg80211]
     [] cfg80211_exit+0x1a/0x40 [cfg80211]

Fix in the same way by grabbing the netlink table lock
before doing rcu_read_lock().

Signed-off-by: Johannes Berg 
Signed-off-by: David S. Miller

genetlink: fix netns vs. netlink table locking

2009-09-15T00:02:50+00:00

Since my commits introducing netns awareness into
genetlink we can get this problem:

BUG: scheduling while atomic: modprobe/1178/0x00000002
2 locks held by modprobe/1178:
 #0:  (genl_mutex){+.+.+.}, at: [] genl_register_mc_grou
 #1:  (rcu_read_lock){.+.+..}, at: [] genl_register_mc_g
Pid: 1178, comm: modprobe Not tainted 2.6.31-rc8-wl-34789-g95cb731-dirty #
Call Trace:
 [] __schedule_bug+0x85/0x90
 [] schedule+0x108/0x588
 [] netlink_table_grab+0xa1/0xf0
 [] netlink_change_ngroups+0x47/0x100
 [] genl_register_mc_group+0x12f/0x290

because I overlooked that netlink_table_grab() will
schedule, thinking it was just the rwlock. However,
in the contention case, that isn't actually true.

Fix this by letting the code grab the netlink table
lock first and then the RCU for netns protection.

Signed-off-by: Johannes Berg 
Signed-off-by: David S. Miller

netlink: constify nlmsghdr arguments

2009-08-25T14:07:40+00:00

Consitfy nlmsghdr arguments to a couple of functions as preparation
for the next patch, which will constify the netlink message data in
all nfnetlink users.

Signed-off-by: Patrick McHardy

netlink: add NETLINK_NO_ENOBUFS socket flag

2009-03-24T23:37:55+00:00

This patch adds the NETLINK_NO_ENOBUFS socket flag. This flag can
be used by unicast and broadcast listeners to avoid receiving
ENOBUFS errors.

Generally speaking, ENOBUFS errors are useful to notify two things
to the listener:

a) You may increase the receiver buffer size via setsockopt().
b) You have lost messages, you may be out of sync.

In some cases, ignoring ENOBUFS errors can be useful. For example:

a) nfnetlink_queue: this subsystem does not have any sort of resync
method and you can decide to ignore ENOBUFS once you have set a
given buffer size.

b) ctnetlink: you can use this together with the socket flag
NETLINK_BROADCAST_SEND_ERROR to stop getting ENOBUFS errors as
you do not need to resync (packets whose event are not delivered
are drop to provide reliable logging and state-synchronization).

Moreover, the use of NETLINK_NO_ENOBUFS also reduces a "go up, go down"
effect in terms of performance which is due to the netlink congestion
control when the listener cannot back off. The effect is the following:

1) throughput rate goes up and netlink messages are inserted in the
receiver buffer.
2) Then, netlink buffer fills and overruns (set on nlk->state bit 0).
3) While the listener empties the receiver buffer, netlink keeps
dropping messages. Thus, throughput goes dramatically down.
4) Then, once the listener has emptied the buffer (nlk->state
bit 0 is set off), goto step 1.

This effect is easy to trigger with netlink broadcast under heavy
load, and it is more noticeable when using a big receiver buffer.
You can find some results in [1] that show this problem.

[1] http://1984.lsi.us.es/linux/netlink/

This patch also includes the use of sk_drop to account the number of
netlink messages drop due to overrun. This value is shown in
/proc/net/netlink.

Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: David S. Miller

netlink: add NETLINK_BROADCAST_ERROR socket option

2009-02-20T09:01:08+00:00

This patch adds NETLINK_BROADCAST_ERROR which is a netlink
socket option that the listener can set to make netlink_broadcast()
return errors in the delivery to the caller. This option is useful
if the caller of netlink_broadcast() do something with the result
of the message delivery, like in ctnetlink where it drops a network
packet if the event delivery failed, this is used to enable reliable
logging and state-synchronization. If this socket option is not set,
netlink_broadcast() only reports ESRCH errors and silently ignore
ENOBUFS errors, which is what most netlink_broadcast() callers
should do.

This socket option is based on a suggestion from Patrick McHardy.
Patrick McHardy can exchange this patch for a beer from me ;).

Signed-off-by: Pablo Neira Ayuso 
Acked-by: Patrick McHardy 
Signed-off-by: David S. Miller

netlink: avoid memset of 0 bytes sparse warning

2008-11-20T12:08:29+00:00

A netlink attribute padding of zero triggers this sparse warning:

include/linux/netlink.h:245:8: warning: memset with byte count of 0

Avoid the memset when the size parameter is constant and requires no padding.

Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller

netlink: Remove nonblock parameter from netlink_attachskb

2008-06-05T18:23:39+00:00

Signed-off-by: Denis V. Lunev 
Signed-off-by: David S. Miller

Audit: collect sessionid in netlink messages

2008-04-28T10:18:03+00:00

Previously I added sessionid output to all audit messages where it was
available but we still didn't know the sessionid of the sender of
netlink messages.  This patch adds that information to netlink messages
so we can audit who sent netlink messages.

Signed-off-by: Eric Paris 
Signed-off-by: Al Viro

[IPV4] fib_trie: rescan if key is lost during dump

2008-02-01T03:28:23+00:00

Normally during a dump the key of the last dumped entry is used for
continuation, but since lock is dropped it might be lost. In that case
fallback to the old counter based N^2 behaviour.  This means the dump
will end up skipping some routes which matches what FIB_HASH does.

Signed-off-by: Stephen Hemminger 
Signed-off-by: David S. Miller

[NETNS]: Consolidate kernel netlink socket destruction.

2008-01-28T23:08:07+00:00

Create a specific helper for netlink kernel socket disposal. This just
let the code look better and provides a ground for proper disposal
inside a namespace.

Signed-off-by: Denis V. Lunev 
Tested-by: Alexey Dobriyan 
Signed-off-by: David S. Miller