On Fri, Dec 04, 2020 at 06:01:52PM +0100, Thomas Gleixner wrote: > From: Thomas Gleixner <t...@linutronix.de> > > RT requires the softirq processing and local bottomhalf disabled regions to > be preemptible. Using the normal preempt count based serialization is > therefore not possible because this implicitely disables preemption. > > RT kernels use a per CPU local lock to serialize bottomhalfs. As > local_bh_disable() can nest the lock can only be acquired on the outermost > invocation of local_bh_disable() and released when the nest count becomes > zero. Tasks which hold the local lock can be preempted so its required to > keep track of the nest count per task. > > Add a RT only counter to task struct and adjust the relevant macros in > preempt.h. > > Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Reviewed-by: Frederic Weisbecker <frede...@kernel.org>
