Re: [PATCH net] net: sched: flower: don't call synchronize_rcu() on mask creation

[David Miller <davem@davemloft.net>]

From: Vlad Buslov <vladbu@mellanox.com>
Date: Thu, 13 Jun 2019 17:54:04 +0300

> Current flower mask creating code assumes that temporary mask that is used
> when inserting new filter is stack allocated. To prevent race condition
> with data patch synchronize_rcu() is called every time fl_create_new_mask()
> replaces temporary stack allocated mask. As reported by Jiri, this
> increases runtime of creating 20000 flower classifiers from 4 seconds to
> 163 seconds. However, this design is no longer necessary since temporary
> mask was converted to be dynamically allocated by commit 2cddd2014782
> ("net/sched: cls_flower: allocate mask dynamically in fl_change()").
> 
> Remove synchronize_rcu() calls from mask creation code. Instead, refactor
> fl_change() to always deallocate temporary mask with rcu grace period.
> 
> Fixes: 195c234d15c9 ("net: sched: flower: handle concurrent mask insertion")
> Reported-by: Jiri Pirko <jiri@mellanox.com>
> Signed-off-by: Vlad Buslov <vladbu@mellanox.com>

Applied, thanks.