7f43cda650
[ Upstream commit 71921a9606ddbcc1d98c00eca7ae82c373d1fecd ] rcutorture is generating some nesting scenarios that are not compatible on PREEMPT_RT. For example: preempt_disable(); rcu_read_lock_bh(); preempt_enable(); rcu_read_unlock_bh(); The problem here is that on PREEMPT_RT the bottom halves have to be disabled and enabled in preemptible context. Reorder locking: start with BH locking and continue with then with disabling preemption or interrupts. In the unlocking do it reverse by first enabling interrupts and preemption and BH at the very end. Ensure that on PREEMPT_RT BH locking remains unchanged if in non-preemptible context. Link: https://lkml.kernel.org/r/20190911165729.11178-6-swood@redhat.com Link: https://lkml.kernel.org/r/20210819182035.GF4126399@paulmck-ThinkPad-P17-Gen-1 Signed-off-by: Scott Wood <swood@redhat.com> [bigeasy: Drop ATOM_BH, make it only about changing BH in atomic context. Allow enabling RCU in IRQ-off section. Reword commit message.] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.