From a6e0fc8514d41dfdd98b1d15cacc432cf040f8af Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 8 Sep 2010 14:15:32 -0700 Subject: net: introduce rcu_dereference_rtnl We use rcu_dereference_check(p, rcu_read_lock_held() || lockdep_rtnl_is_held()) several times in network stack. More usages to come too, so its time to create a helper. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/rtnetlink.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include/linux/rtnetlink.h') diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index 58d44491880f..263690d991a8 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -749,6 +749,17 @@ extern int rtnl_is_locked(void); extern int lockdep_rtnl_is_held(void); #endif /* #ifdef CONFIG_PROVE_LOCKING */ +/** + * rcu_dereference_rtnl - rcu_dereference with debug checking + * @p: The pointer to read, prior to dereferencing + * + * Do an rcu_dereference(p), but check caller either holds rcu_read_lock() + * or RTNL + */ +#define rcu_dereference_rtnl(p) \ + rcu_dereference_check(p, rcu_read_lock_held() || \ + lockdep_rtnl_is_held()) + extern void rtnetlink_init(void); extern void __rtnl_unlock(void); -- cgit v1.2.2 From 7dff59efbb0e8b0f81c95fd40379c0d0c757c808 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 15 Sep 2010 11:07:15 +0000 Subject: net: add rtnl_dereference() We sometime want to dereference an rcu protected pointer while holding RTNL. Use a macro to hide all lockdep details. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/rtnetlink.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/linux/rtnetlink.h') diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index 263690d991a8..68c436bddc88 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -760,6 +760,15 @@ extern int lockdep_rtnl_is_held(void); rcu_dereference_check(p, rcu_read_lock_held() || \ lockdep_rtnl_is_held()) +/** + * rtnl_dereference - rcu_dereference with debug checking + * @p: The pointer to read, prior to dereferencing + * + * Do an rcu_dereference(p), but check caller holds RTNL + */ +#define rtnl_dereference(p) \ + rcu_dereference_check(p, lockdep_rtnl_is_held()) + extern void rtnetlink_init(void); extern void __rtnl_unlock(void); -- cgit v1.2.2 From 24824a09e35402b8d58dcc5be803a5ad3937bdba Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sat, 2 Oct 2010 06:11:55 +0000 Subject: net: dynamic ingress_queue allocation ingress being not used very much, and net_device->ingress_queue being quite a big object (128 or 256 bytes), use a dynamic allocation if needed (tc qdisc add dev eth0 ingress ...) dev_ingress_queue(dev) helper should be used only with RTNL taken. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/rtnetlink.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/linux/rtnetlink.h') diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index 68c436bddc88..0bb7b48632bd 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -6,6 +6,7 @@ #include #include #include +#include /* rtnetlink families. Values up to 127 are reserved for real address * families, values above 128 may be used arbitrarily. @@ -769,6 +770,13 @@ extern int lockdep_rtnl_is_held(void); #define rtnl_dereference(p) \ rcu_dereference_check(p, lockdep_rtnl_is_held()) +static inline struct netdev_queue *dev_ingress_queue(struct net_device *dev) +{ + return rtnl_dereference(dev->ingress_queue); +} + +extern struct netdev_queue *dev_ingress_queue_create(struct net_device *dev); + extern void rtnetlink_init(void); extern void __rtnl_unlock(void); -- cgit v1.2.2 From 29fa060eab3f524d338566d34c1d9e704579ae5e Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Tue, 5 Oct 2010 00:29:48 -0700 Subject: 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 Signed-off-by: David S. Miller --- include/linux/rtnetlink.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'include/linux/rtnetlink.h') 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) { -- cgit v1.2.2