70ae7b0ce0
An early check on synchronize_rcu[_expedited]() tries to determine if the current CPU is in UP mode on an SMP no-preempt kernel, in which case there is no need to start a grace period since the current assumed quiescent state is all we need. However the preemption mode doesn't take into account the boot selected preemption mode under CONFIG_PREEMPT_DYNAMIC=y, missing a possible early return if the running flavour is "none" or "voluntary". Use the shiny new preempt mode accessors to fix this. However, avoid invoking them during early boot because doing so triggers a WARN_ON_ONCE(). [ paulmck: Update for mainlined API. ] Reported-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Paul E. McKenney <paulmck@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.