On Thu, Sep 30, 2021 at 12:10:01AM +0200, Frederic Weisbecker wrote: > PREEMPT_RT has made rcu_core() preemptible, making it unsafe against > concurrent NOCB (de-)offloading. > > Thomas suggested to drop the local_lock() based solution and simply > check the offloaded state while context looks safe but that's not > enough. Here is a bit of rework. > > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git > rcu/rt > > HEAD: aac1c58961446c731f2e989bd822ca1fd2659bad Many of these look quite good, but any chance of getting an official Tested-by from someone in the -rt community? Thanx, Paul > Thanks, > Frederic > --- > > Frederic Weisbecker (10): > rcu/nocb: Make local rcu_nocb_lock_irqsave() safe against concurrent deoffloading > rcu/nocb: Prepare state machine for a new step > rcu/nocb: Invoke rcu_core() at the start of deoffloading > rcu/nocb: Make rcu_core() callbacks acceleration (de-)offloading safe > rcu/nocb: Check a stable offloaded state to manipulate qlen_last_fqs_check > rcu/nocb: Use appropriate rcu_nocb_lock_irqsave() > rcu/nocb: Limit number of softirq callbacks only on softirq > rcu: Fix callbacks processing time limit retaining cond_resched() > rcu: Apply callbacks processing time limit only on softirq > rcu/nocb: Don't invoke local rcu core on callback overload from nocb kthread > > Thomas Gleixner (1): > rcu/nocb: Make rcu_core() callbacks acceleration preempt-safe > > > include/linux/rcu_segcblist.h | 51 +++++++++++++++++++------- > kernel/rcu/rcu_segcblist.c | 10 ++--- > kernel/rcu/rcu_segcblist.h | 7 ++-- > kernel/rcu/tree.c | 85 ++++++++++++++++++++++++++++++------------- > kernel/rcu/tree.h | 16 +++++--- > kernel/rcu/tree_nocb.h | 29 ++++++++++++--- > 6 files changed, 136 insertions(+), 62 deletions(-)
