linux-toradex.git/Documentation/RCU/Design/Requirements, branch v4.16

Merge branches 'cond_resched.2017.12.04a', 'dyntick.2017.11.28a', 'fixes.2017.12.11a', 'srbd.2017.12.05a' and 'torture.2017.12.11a' into HEAD

2017-12-11T17:21:58+00:00

cond_resched.2017.12.04a: Convert cond_resched_rcu_qs() to cond_resched()
dyntick.2017.11.28a: Make RCU dynticks handle interrupts from NMI
fixes.2017.12.11a: Miscellaneous fixes
srbd.2017.12.05a: Remove now-redundant smp_read_barrier_depends()
torture.2017.12.11a: Torture-testing update

doc: De-emphasize smp_read_barrier_depends

2017-12-05T19:57:53+00:00

This commit keeps only the historical and low-level discussion of
smp_read_barrier_depends().

Signed-off-by: Paul E. McKenney 
[ paulmck: Adjusted to allow for David Howells feedback on prior commit. ]

doc: Eliminate cond_resched_rcu_qs() in favor of cond_resched()

2017-12-04T18:28:59+00:00

Now that cond_resched() also provides RCU quiescent states when
needed, it can be used in place of cond_resched_rcu_qs().  This
commit therefore documents this change.

Signed-off-by: Paul E. McKenney

doc: Set down RCU's scheduling-clock-interrupt needs

2017-08-17T14:31:14+00:00

This commit documents the situations in which RCU needs the
scheduling-clock interrupt to be enabled, along with the consequences
of failing to meet RCU's needs in this area.

Signed-off-by: Paul E. McKenney

rcu: Remove debugfs tracing

2017-06-09T01:52:43+00:00

RCU's debugfs tracing used to be the only reasonable low-level debug
information available, but ftrace and event tracing has since surpassed
the RCU debugfs level of usefulness.  This commit therefore removes
RCU's debugfs tracing.

Signed-off-by: Paul E. McKenney

rcu: Remove SPARSE_RCU_POINTER Kconfig option

2017-06-09T01:52:41+00:00

The sparse-based checking for non-RCU accesses to RCU-protected pointers
has been around for a very long time, and it is now the only type of
sparse-based checking that is optional.  This commit therefore makes
it unconditional.

Reported-by: Ingo Molnar 
Signed-off-by: Paul E. McKenney 
Cc: Fengguang Wu

rcu: Remove nohz_full full-system-idle state machine

2017-06-09T01:52:39+00:00

The NO_HZ_FULL_SYSIDLE full-system-idle capability was added in 2013
by commit 0edd1b1784cb ("nohz_full: Add full-system-idle state machine"),
but has not been used.  This commit therefore removes it.

If it turns out to be needed later, this commit can always be reverted.

Signed-off-by: Paul E. McKenney 
Cc: Frederic Weisbecker 
Cc: Rik van Riel 
Cc: Ingo Molnar 
Acked-by: Linus Torvalds

doc: Take tail recursion into account in RCU requirements

2017-06-08T15:25:34+00:00

This commit classifies tail recursion as an alternative way to write
a loop, with similar limitations.

Signed-off-by: Paul E. McKenney

srcu: Document auto-expediting requirement

2017-06-08T15:25:33+00:00

This commit documents the auto-expediting requirement satisfied by
commits 2da4b2a7fd8d ("srcu: Expedite first synchronize_srcu() when idle")
and 22607d66bbc3 ("srcu: Specify auto-expedite holdoff time").

Signed-off-by: Paul E. McKenney

doc: Update requirements based on recent changes

2017-04-12T15:23:41+00:00

These changes include lighter-weight expedited grace periods, the fact
that expedited grace periods and rcu_barrier() no longer block CPU
hotplug, some HTML font fixups, noting that rcu_barrier() need not wait
for a grace period (even if callbacks are posted), the fact that SRCU
read-side critical sections can be used from offline CPUs, and the fact
that SRCU now maintains per-CPU callback lists.

Signed-off-by: Paul E. McKenney