diff options
| author | David S. Miller <davem@davemloft.net> | 2010-10-05 00:29:48 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-10-05 00:29:48 -0700 |
| commit | 29fa060eab3f524d338566d34c1d9e704579ae5e (patch) | |
| tree | 5ec18e56dc3321dda6e1fa76b08b32043f8c88e9 /include/linux/rtnetlink.h | |
| parent | 13f5bf18ba657d2d17c8fcf584e50359c718dd4b (diff) | |
| download | lwn-29fa060eab3f524d338566d34c1d9e704579ae5e.tar.gz lwn-29fa060eab3f524d338566d34c1d9e704579ae5e.zip | |
net: relax rtnl_dereference()
rtnl_dereference() is used in contexts where RTNL is held, to fetch an
RCU protected pointer.
Updates to this pointer are prevented by RTNL, so we dont need
smp_read_barrier_depends() and the ACCESS_ONCE() provided in
rcu_dereference_check().
rtnl_dereference() is mainly a macro to document the locking invariant.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/rtnetlink.h')
| -rw-r--r-- | include/linux/rtnetlink.h | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index 0bb7b48632bd..d42f274418b8 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -755,20 +755,22 @@ extern int lockdep_rtnl_is_held(void); * @p: The pointer to read, prior to dereferencing * * Do an rcu_dereference(p), but check caller either holds rcu_read_lock() - * or RTNL + * or RTNL. Note : Please prefer rtnl_dereference() or rcu_dereference() */ #define rcu_dereference_rtnl(p) \ rcu_dereference_check(p, rcu_read_lock_held() || \ lockdep_rtnl_is_held()) /** - * rtnl_dereference - rcu_dereference with debug checking + * rtnl_dereference - fetch RCU pointer when updates are prevented by RTNL * @p: The pointer to read, prior to dereferencing * - * Do an rcu_dereference(p), but check caller holds RTNL + * Return the value of the specified RCU-protected pointer, but omit + * both the smp_read_barrier_depends() and the ACCESS_ONCE(), because + * caller holds RTNL. */ #define rtnl_dereference(p) \ - rcu_dereference_check(p, lockdep_rtnl_is_held()) + rcu_dereference_protected(p, lockdep_rtnl_is_held()) static inline struct netdev_queue *dev_ingress_queue(struct net_device *dev) { |