On 14.01.2016 15:50, Sebastian Andrzej Siewior wrote:

* Thomas Gleixner | 2016-01-13 18:31:46 [+0100]:

quoted

On Wed, 13 Jan 2016, Sebastian Andrzej Siewior wrote:

quoted

+#ifdef CONFIG_PREEMPT_RT_FULL
+static inline int dev_recursion_level(void)
+{
+	return atomic_read(&current->xmit_recursion);

Why would you need an atomic here. current does hardly race against itself.

right.

We are just adding a second recursion limit solely to openvswitch which 
has the same problem:

https://patchwork.ozlabs.org/patch/566769/

This time also we depend on rcu_read_lock marking the section being 
nonpreemptible. Nice would be a more generic solution here which doesn't 
need to always add something to *current.

Thanks,
Hannes