[PATCH net-next v2 1/2] rtnetlink: add guard for RTNL

[PATCH net-next v2 1/2] rtnetlink: add guard for RTNL

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

The new guard/scoped_gard can be useful for the RTNL as well,
so add a guard definition for it. It gets used like

 {
   guard(rtnl)();
   // RTNL held until end of block
 }

or

  scoped_guard(rtnl) {
    // RTNL held in this block
  }

as with any other guard/scoped_guard.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
v2: resend
---
 include/linux/rtnetlink.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index cdfc897f1e3c..a7da7dfc06a2 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -7,6 +7,7 @@
 #include <linux/netdevice.h>
 #include <linux/wait.h>
 #include <linux/refcount.h>
+#include <linux/cleanup.h>
 #include <uapi/linux/rtnetlink.h>
 
 extern int rtnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, u32 group, int echo);
@@ -46,6 +47,8 @@ extern int rtnl_is_locked(void);
 extern int rtnl_lock_killable(void);
 extern bool refcount_dec_and_rtnl_lock(refcount_t *r);
 
+DEFINE_LOCK_GUARD_0(rtnl, rtnl_lock(), rtnl_unlock())
+
 extern wait_queue_head_t netdev_unregistering_wq;
 extern atomic_t dev_unreg_count;
 extern struct rw_semaphore pernet_ops_rwsem;
-- 
2.44.0

[PATCH net-next v2 2/2] netdevice: add DEFINE_FREE() for dev_put

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

For short netdev holds within a function there are still a lot of
users of dev_put() rather than netdev_put(). Add DEFINE_FREE() to
allow making those safer.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
v2: resend
---
 include/linux/netdevice.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index cb37817d6382..f6c0d731fa35 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -4127,6 +4127,8 @@ static inline void dev_put(struct net_device *dev)
 	netdev_put(dev, NULL);
 }
 
+DEFINE_FREE(dev_put, struct net_device *, if (_T) dev_put(_T))
+
 static inline void netdev_ref_replace(struct net_device *odev,
 				      struct net_device *ndev,
 				      netdevice_tracker *tracker,
-- 
2.44.0

Re: [PATCH net-next v2 2/2] netdevice: add DEFINE_FREE() for dev_put

[Simon Horman]

On Thu, Mar 28, 2024 at 08:27:50AM +0100, Johannes Berg wrote:
> From: Johannes Berg <johannes.berg@intel.com>
> 
> For short netdev holds within a function there are still a lot of
> users of dev_put() rather than netdev_put(). Add DEFINE_FREE() to
> allow making those safer.
> 
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH net-next v2 1/2] rtnetlink: add guard for RTNL

[Simon Horman]

On Thu, Mar 28, 2024 at 08:27:49AM +0100, Johannes Berg wrote:
> From: Johannes Berg <johannes.berg@intel.com>
> 
> The new guard/scoped_gard can be useful for the RTNL as well,
> so add a guard definition for it. It gets used like
> 
>  {
>    guard(rtnl)();
>    // RTNL held until end of block
>  }
> 
> or
> 
>   scoped_guard(rtnl) {
>     // RTNL held in this block
>   }
> 
> as with any other guard/scoped_guard.
> 
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH net-next v2 1/2] rtnetlink: add guard for RTNL

[Jiri Pirko]

Thu, Mar 28, 2024 at 08:27:49AM CET, johannes@sipsolutions.net wrote:
>From: Johannes Berg <johannes.berg@intel.com>
>
>The new guard/scoped_gard can be useful for the RTNL as well,
>so add a guard definition for it. It gets used like
>
> {
>   guard(rtnl)();
>   // RTNL held until end of block
> }
>
>or
>
>  scoped_guard(rtnl) {
>    // RTNL held in this block
>  }
>
>as with any other guard/scoped_guard.
>
>Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Since you add couple of helpers, I believe it is a nice custom to add a
couple of patches that actually uses them. Would that make sense?


>---
>v2: resend
>---
> include/linux/rtnetlink.h | 3 +++
> 1 file changed, 3 insertions(+)
>
>diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
>index cdfc897f1e3c..a7da7dfc06a2 100644
>--- a/include/linux/rtnetlink.h
>+++ b/include/linux/rtnetlink.h
>@@ -7,6 +7,7 @@
> #include <linux/netdevice.h>
> #include <linux/wait.h>
> #include <linux/refcount.h>
>+#include <linux/cleanup.h>
> #include <uapi/linux/rtnetlink.h>
> 
> extern int rtnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, u32 group, int echo);
>@@ -46,6 +47,8 @@ extern int rtnl_is_locked(void);
> extern int rtnl_lock_killable(void);
> extern bool refcount_dec_and_rtnl_lock(refcount_t *r);
> 
>+DEFINE_LOCK_GUARD_0(rtnl, rtnl_lock(), rtnl_unlock())
>+
> extern wait_queue_head_t netdev_unregistering_wq;
> extern atomic_t dev_unreg_count;
> extern struct rw_semaphore pernet_ops_rwsem;
>-- 
>2.44.0
>

Re: [PATCH net-next v2 1/2] rtnetlink: add guard for RTNL

[Jakub Kicinski]

On Tue, 2 Apr 2024 14:31:31 +0200 Jiri Pirko wrote:
> >Signed-off-by: Johannes Berg <johannes.berg@intel.com>  
> 
> Since you add couple of helpers, I believe it is a nice custom to add a
> couple of patches that actually uses them. Would that make sense?

We discussed on v1, we want to open up the use in new code but
I don't see any benefit in rewriting existing, well tested code.
The first users are likely to be in wireless.

Re: [PATCH net-next v2 1/2] rtnetlink: add guard for RTNL

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by David S. Miller <davem@davemloft.net>:

On Thu, 28 Mar 2024 08:27:49 +0100 you wrote:
> From: Johannes Berg <johannes.berg@intel.com>
> 
> The new guard/scoped_gard can be useful for the RTNL as well,
> so add a guard definition for it. It gets used like
> 
>  {
>    guard(rtnl)();
>    // RTNL held until end of block
>  }
> 
> [...]

Here is the summary with links:
  - [net-next,v2,1/2] rtnetlink: add guard for RTNL
    https://git.kernel.org/netdev/net-next/c/464eb03c4a7c
  - [net-next,v2,2/2] netdevice: add DEFINE_FREE() for dev_put
    https://git.kernel.org/netdev/net-next/c/b1f81b9a535b

You are awesome, thank you!
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