Patchwork [net-next-2.6] net: introduce rcu_dereference_read_lock_or_rtnl

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Submitter Eric Dumazet
Date Sept. 7, 2010, 8:11 p.m.
Message ID <1283890291.2634.143.camel@edumazet-laptop>
Download mbox | patch
Permalink /patch/64058/
State Superseded
Delegated to: David Miller
Headers show

Comments

Eric Dumazet - Sept. 7, 2010, 8:11 p.m.
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 <eric.dumazet@gmail.com>
---
include/linux/rtnetlink.h |   12 ++++++++++++



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Jarek Poplawski - Sept. 7, 2010, 8:49 p.m.
Eric Dumazet wrote, On 09/07/2010 10:11 PM:

> 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 <eric.dumazet@gmail.com>
> ---
> include/linux/rtnetlink.h |   12 ++++++++++++
> 
> diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
> index 58d4449..5ba48bb 100644
> --- a/include/linux/rtnetlink.h
> +++ b/include/linux/rtnetlink.h
> @@ -745,10 +745,22 @@ extern void rtnl_lock(void);
>  extern void rtnl_unlock(void);
>  extern int rtnl_trylock(void);
>  extern int rtnl_is_locked(void);
> +
>  #ifdef CONFIG_PROVE_LOCKING
>  extern int lockdep_rtnl_is_held(void);
>  #endif /* #ifdef CONFIG_PROVE_LOCKING */
>  
> +/**
> + * rcu_dereference_read_lock_or_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_read_lock_or_rtnl(p)


My proposal is to shorten the name, and since rcu_read_lock
part seems obvious, maybe rcu_dereference_rtnl() only?

Jarek P.

				\
> +		rcu_dereference_check(p, rcu_read_lock_held() ||	\
> +					 lockdep_rtnl_is_held());
> +
>  extern void rtnetlink_init(void);
>  extern void __rtnl_unlock(void);
>  
> 
> 
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> 


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Patch

diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index 58d4449..5ba48bb 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -745,10 +745,22 @@  extern void rtnl_lock(void);
 extern void rtnl_unlock(void);
 extern int rtnl_trylock(void);
 extern int rtnl_is_locked(void);
+
 #ifdef CONFIG_PROVE_LOCKING
 extern int lockdep_rtnl_is_held(void);
 #endif /* #ifdef CONFIG_PROVE_LOCKING */
 
+/**
+ * rcu_dereference_read_lock_or_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_read_lock_or_rtnl(p)				\
+		rcu_dereference_check(p, rcu_read_lock_held() ||	\
+					 lockdep_rtnl_is_held());
+
 extern void rtnetlink_init(void);
 extern void __rtnl_unlock(void);