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| author | Jarek Poplawski <jarkao2@gmail.com> | 2008-03-20 17:05:13 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2008-03-20 17:05:13 -0700 |
| commit | 94833dfb8c98ed4ca1944dd2c1339d88a2d1c758 (patch) | |
| tree | c059b5aec8432d82c73f1f3038132f364502d265 /drivers/net/ifb.c | |
| parent | 38fe999e2286139cccdaa500a81bd49a16a81158 (diff) | |
| download | lwn-94833dfb8c98ed4ca1944dd2c1339d88a2d1c758.tar.gz lwn-94833dfb8c98ed4ca1944dd2c1339d88a2d1c758.zip | |
[NET] ifb: set separate lockdep classes for queue locks
[ 10.536424] =======================================================
[ 10.536424] [ INFO: possible circular locking dependency detected ]
[ 10.536424] 2.6.25-rc3-devel #3
[ 10.536424] -------------------------------------------------------
[ 10.536424] swapper/0 is trying to acquire lock:
[ 10.536424] (&dev->queue_lock){-+..}, at: [<c0299b4a>]
dev_queue_xmit+0x175/0x2f3
[ 10.536424]
[ 10.536424] but task is already holding lock:
[ 10.536424] (&p->tcfc_lock){-+..}, at: [<f8a67154>] tcf_mirred+0x20/0x178
[act_mirred]
[ 10.536424]
[ 10.536424] which lock already depends on the new lock.
lockdep warns of locking order while using ifb with sch_ingress and
act_mirred: ingress_lock, tcfc_lock, queue_lock (usually queue_lock
is at the beginning). This patch is only to tell lockdep that ifb is
a different device (e.g. from eth) and has its own pair of queue
locks. (This warning is a false-positive in common scenario of using
ifb; yet there are possible situations, when this order could be
dangerous; lockdep should warn in such a case.) (With suggestions by
David S. Miller)
Reported-and-tested-by: Denys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ifb.c')
| -rw-r--r-- | drivers/net/ifb.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/net/ifb.c b/drivers/net/ifb.c index 15949d3df17e..af233b591534 100644 --- a/drivers/net/ifb.c +++ b/drivers/net/ifb.c @@ -35,6 +35,7 @@ #include <linux/moduleparam.h> #include <net/pkt_sched.h> #include <net/net_namespace.h> +#include <linux/lockdep.h> #define TX_TIMEOUT (2*HZ) @@ -227,6 +228,16 @@ static struct rtnl_link_ops ifb_link_ops __read_mostly = { module_param(numifbs, int, 0); MODULE_PARM_DESC(numifbs, "Number of ifb devices"); +/* + * dev_ifb->queue_lock is usually taken after dev->ingress_lock, + * reversely to e.g. qdisc_lock_tree(). It should be safe until + * ifb doesn't take dev->queue_lock with dev_ifb->ingress_lock. + * But lockdep should know that ifb has different locks from dev. + */ +static struct lock_class_key ifb_queue_lock_key; +static struct lock_class_key ifb_ingress_lock_key; + + static int __init ifb_init_one(int index) { struct net_device *dev_ifb; @@ -246,6 +257,10 @@ static int __init ifb_init_one(int index) err = register_netdevice(dev_ifb); if (err < 0) goto err; + + lockdep_set_class(&dev_ifb->queue_lock, &ifb_queue_lock_key); + lockdep_set_class(&dev_ifb->ingress_lock, &ifb_ingress_lock_key); + return 0; err: |