Commit 8344496e8b49 ("rcu-tasks: Conditionally compile
show_rcu_tasks_gp_kthreads()") introduced conditional
compilation of several functions, but forgot one occurrence of
show_rcu_tasks_classic_gp_kthread() that causes the compiler to warn of
an unused static function.  This commit uses "static inline" to avoid
these complaints and possibly also to avoid emitting an actual definition
of this function.

Fixes: 8344496e8b49 ("rcu-tasks: Conditionally compile show_rcu_tasks_gp_kthreads()")
Cc: <stable@vger.kernel.org> # 5.8.x
Reported-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

doc.2020.06.29a:  Documentation updates.
fixes.2020.06.29a:  Miscellaneous fixes.
kfree_rcu.2020.06.29a:  kfree_rcu() updates.
rcu-tasks.2020.06.29a:  RCU Tasks updates.
scale.2020.06.29a:  Read-side scalability tests.
srcu.2020.06.29a:  SRCU updates.
torture.2020.06.29a:  Torture-test updates.

The synchronize_rcu_tasks_trace() header comment incorrectly claims that
any number of things delimit RCU Tasks Trace read-side critical sections,
when in fact only rcu_read_lock_trace() and rcu_read_unlock_trace() do so.
This commit therefore fixes this comment, and, while in the area, fixes
a typo in the rcu_read_lock_trace() header comment.

Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

This commit declares trc_n_readers_need_end and trc_wait static and
replaced a "&" with "&&".  The "&" happened to work because the values
are bool, but accidents waiting to happen and all that...

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

The show_rcu_tasks_gp_kthreads() function is not invoked by Tiny RCU,
but is nevertheless defined in Tiny RCU builds that enable Tasks Trace
RCU.  This commit therefore conditionally compiles this function so
that it is defined only in builds that actually use it.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

The rcu_tasks_postscan() function is not used outside of RCU's tasks.h
file, so this commit makes it be static.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

This commit converts the long-standing schedule_timeout_interruptible()
and schedule_timeout_uninterruptible() calls used by the various Tasks
RCU's grace-period kthreads to schedule_timeout_idle().  This conversion
avoids polluting the load-average with Tasks-RCU-related sleeping.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

This commit allows TASKS_TRACE_RCU to be used independently of TASKS_RCU
and vice versa.

[ paulmck: Fix conditional compilation per kbuild test robot feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

This commit adds a failure-return count for smp_call_function_single(),
and adds this to the console messages for rcutorture writer stalls and at
the end of rcutorture testing.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

This commit adds a counter for the number of times the quiescent state
was an idle task associated with an offline CPU, and prints this count
at the end of rcutorture runs and at stall time.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>