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2019-03-26doc: Remove obsolete RCU update functions from RCU documentationPaul E. McKenney
Now that synchronize_rcu_bh, synchronize_rcu_bh_expedited, call_rcu_bh, rcu_barrier_bh, synchronize_sched, synchronize_sched_expedited, call_rcu_sched, rcu_barrier_sched, get_state_synchronize_sched, and cond_synchronize_sched are obsolete, let's remove them from the documentation aside from a small historical section. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-02-09Merge branches 'doc.2019.01.26a', 'fixes.2019.01.26a', 'sil.2019.01.26a', ↵Paul E. McKenney
'spdx.2019.02.09a', 'srcu.2019.01.26a' and 'torture.2019.01.26a' into HEAD doc.2019.01.26a: Documentation updates. fixes.2019.01.26a: Miscellaneous fixes. sil.2019.01.26a: Removal of a few more spin_is_locked() instances. spdx.2019.02.09a: Add SPDX identifiers to RCU files srcu.2019.01.26a: SRCU updates. torture.2019.01.26a: Torture-test updates.
2019-01-25rcu: Rename rcu_process_callbacks() to rcu_core() for Tree RCUPaul E. McKenney
Although the name rcu_process_callbacks() still makes sense for Tiny RCU, where most of what it does is invoke callbacks, it no longer makes much sense for Tree RCU, especially given that the actually callback invocation is relegated to rcu_do_batch(), or, for no-CBs CPUs, to the rcuo kthreads. Especially in the latter case, rcu_process_callbacks() has very little to do with actual callbacks. A better description of this function is that it performs RCU's core processing. This commit therefore changes the name of Tree RCU's rcu_process_callbacks() function to rcu_core(), which also has the virtue of being consistent with the existing invoke_rcu_core() function. While in the area, the header comment is reworked. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Rename rcu_check_callbacks() to rcu_sched_clock_irq()Paul E. McKenney
The name rcu_check_callbacks() arguably made sense back in the early 2000s when RCU was quite a bit simpler than it is today, but it has become quite misleading, especially with the advent of dyntick-idle and NO_HZ_FULL. The rcu_check_callbacks() function is RCU's hook into the scheduling-clock interrupt, and is now but one of many ways that callbacks get promoted to invocable state. This commit therefore changes the name to rcu_sched_clock_irq(), which is the same number of characters and clearly indicates this function's relation to the rest of the Linux kernel. In addition, for the sake of consistency, rcu_flavor_check_callbacks() is also renamed to rcu_flavor_sched_clock_irq(). While in the area, the header comments for both functions are reworked. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25doc: CPU-hotplug notifiers cannot invoke synchronize_srcu() or srcu_barrier()Paul E. McKenney
SRCU's synchronize_srcu() may not be invoked from CPU-hotplug notifiers, due to the fact that SRCU grace periods make use of timers and the possibility of timers being temporarily stranded on the outgoing CPU. This stranding of timers means that timers posted to the outgoing CPU will not fire until late in the CPU-hotplug process. The problem is that if a notifier is waiting on an SRCU grace period, that grace period is waiting on a timer, and that timer is stranded on the outgoing CPU, then the notifier will never be awakened, in other words, deadlock has occurred. This same situation of course also prohibits srcu_barrier() from being invoked from CPU-hotplug notifiers. This commit therefore updates the requirements to include this restriction. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Determine expedited-GP IPI handler at build timePaul E. McKenney
Back when there could be multiple RCU flavors running in the same kernel at the same time, it was necessary to specify the expedited grace-period IPI handler at runtime. Now that there is only one RCU flavor, the IPI handler can be determined at build time. There is therefore no longer any reason for the RCU-preempt and RCU-sched IPI handlers to have different names, nor is there any reason to pass these handlers in function arguments and in the data structures enclosing workqueues. This commit therefore makes all these changes, pushing the specification of the expedited grace-period IPI handler down to the point of use. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-12doc: Fix "struction" typo in RCU memory-ordering documentationJoel Fernandes (Google)
This commit replaces "struction" with the correct "structure". Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-12doc: RCU scheduler spinlock rcu_read_unlock() restriction remainsPaul E. McKenney
Given RCU flavor consolidation, when rcu_read_unlock() is invoked with interrupts disabled, the reporting of the corresponding quiescent state is deferred until interrupts are re-enabled. There was therefore some hope that this would allow dropping the restriction against holding scheduler spinlocks across an rcu_read_unlock() without disabling interrupts across the entire corresponding RCU read-side critical section. Unfortunately, the need to quickly provide a quiescent state to expedited grace periods sometimes requires a call to raise_softirq() during rcu_read_unlock() execution. Because raise_softirq() can sometimes acquire the scheduler spinlocks, the restriction must remain in effect. This commit therefore updates the RCU requirements documentation accordingly. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-12doc: Make listing in RCU perf/scale requirements use rcu_assign_pointer()Joel Fernandes (Google)
The code listing under this section has a quick quiz that says line 19 uses rcu_access_pointer, but the code listing itself instead uses rcu_dereference(). This commit therefore makes the code listing match the quick quiz. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-12doc: Remove obsolete (non-)requirement about disabling preemptionJoel Fernandes (Google)
The Requirements.html document says "Disabling Preemption Does Not Block Grace Periods". However this is no longer true with the RCU consolidation. This commit therefore removes the obsolete (non-)requirement entirely. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-12doc: rcu: Update description of gp_seq fields in rcu_dataJoel Fernandes (Google)
The rcu_state structure doesn't have a gp_seq_needed field. Update the description under rcu_data accordingly, to reflect this. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: <kernel-team@android.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-12doc: rcu: Better clarify the rcu_segcblist ->len fieldJoel Fernandes (Google)
An important note under the rcu_segcblist description could use a more detailed description. Especially explanation of the scenario where the ->head field may be temporarily NULL making it not wise to rely on it to determine if callbacks are associated with the rcu_segcblist. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: <kernel-team@android.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-12doc: rcu: Update Data-Structures for RCU flavor consolidationJoel Fernandes (Google)
This patch updates all Data-Structures document figures and text and removes some unwanted figures, to reflect the recent work Paul has been doing with consolidating all flavors of RCU. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: <kernel-team@android.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-12doc: Remove rcu_dynticks from Data-StructuresJoel Fernandes (Google)
rcu_dynticks was folded into rcu_data structure. Update the data structures RCU document accordingly. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: <kernel-team@android.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-12doc: Update information about resched_cpuJoel Fernandes (Google)
Since commit fced9c8cfe6b ("rcu: Avoid resched_cpu() when rescheduling the current CPU"), resched_cpu is not directly called from sync_sched_exp_handler. Update the documentation about the same. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: <kernel-team@android.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-08doc: Clarify RCU data-structure comment about rcu_tree fanoutJoel Fernandes (Google)
RCU Data-Structures document describes a trick to test RCU with small number of CPUs but with a taller tree. It wasn't immediately clear how the document arrived at 16 CPUs which also requires setting the FANOUT_LEAF to 2 instead of the default of 16. This commit therefore provides the needed clarification. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: <kernel-team@android.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-08doc: Set down forward-progress requirementsPaul E. McKenney
This commit adds a section to the requirements documentation setting down requirements for grace-period and callback-invocation forward progress. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2018-08-30Merge branches 'doc.2018.08.30a', 'dynticks.2018.08.30b', 'srcu.2018.08.30b' ↵Paul E. McKenney
and 'torture.2018.08.29a' into HEAD doc.2018.08.30a: Documentation updates dynticks.2018.08.30b: RCU flavor consolidation updates and cleanups srcu.2018.08.30b: SRCU updates torture.2018.08.29a: Torture-test updates
2018-08-30rcu: Defer reporting RCU-preempt quiescent states when disabledPaul E. McKenney
This commit defers reporting of RCU-preempt quiescent states at rcu_read_unlock_special() time when any of interrupts, softirq, or preemption are disabled. These deferred quiescent states are reported at a later RCU_SOFTIRQ, context switch, idle entry, or CPU-hotplug offline operation. Of course, if another RCU read-side critical section has started in the meantime, the reporting of the quiescent state will be further deferred. This also means that disabling preemption, interrupts, and/or softirqs will act as an RCU-preempt read-side critical section. This is enforced by checking preempt_count() as needed. Some special cases must be handled on an ad-hoc basis, for example, context switch is a quiescent state even though both the scheduler and do_exit() disable preemption. In these cases, additional calls to rcu_preempt_deferred_qs() override the preemption disabling. Similar logic overrides disabled interrupts in rcu_preempt_check_callbacks() because in this case the quiescent state happened just before the corresponding scheduling-clock interrupt. In theory, this change lifts a long-standing restriction that required that if interrupts were disabled across a call to rcu_read_unlock() that the matching rcu_read_lock() also be contained within that interrupts-disabled region of code. Because the reporting of the corresponding RCU-preempt quiescent state is now deferred until after interrupts have been enabled, it is no longer possible for this situation to result in deadlocks involving the scheduler's runqueue and priority-inheritance locks. This may allow some code simplification that might reduce interrupt latency a bit. Unfortunately, in practice this would also defer deboosting a low-priority task that had been subjected to RCU priority boosting, so real-time-response considerations might well force this restriction to remain in place. Because RCU-preempt grace periods are now blocked not only by RCU read-side critical sections, but also by disabling of interrupts, preemption, and softirqs, it will be possible to eliminate RCU-bh and RCU-sched in favor of RCU-preempt in CONFIG_PREEMPT=y kernels. This may require some additional plumbing to provide the network denial-of-service guarantees that have been traditionally provided by RCU-bh. Once these are in place, CONFIG_PREEMPT=n kernels will be able to fold RCU-bh into RCU-sched. This would mean that all kernels would have but one flavor of RCU, which would open the door to significant code cleanup. Moving to a single flavor of RCU would also have the beneficial effect of reducing the NOCB kthreads by at least a factor of two. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Apply rcu_read_unlock_special() preempt_count() feedback from Joel Fernandes. ] [ paulmck: Adjust rcu_eqs_enter() call to rcu_preempt_deferred_qs() in response to bug reports from kbuild test robot. ] [ paulmck: Fix bug located by kbuild test robot involving recursion via rcu_preempt_deferred_qs(). ]
2018-08-30doc: Fix broken HTML directivePaul E. McKenney
This commit adds the needed "<". Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2018-08-30doc: Update removal of RCU-bh/sched update machineryPaul E. McKenney
The RCU-bh update API is now defined in terms of that of RCU-bh and RCU-sched, so this commit updates the documentation accordingly. In addition, although RCU-sched persists in !PREEMPT kernels, in the PREEMPT case its update API is now defined in terms of that of RCU-preempt, so this commit also updates the documentation accordingly. While in the area, this commit removes the documentation for the now-obsolete synchronize_rcu_mult() and clarifies the Tasks RCU documentation. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2018-08-29doc: Improve rcu_dynticks::dynticks documentationJoel Fernandes (Google)
The very useful RCU Data-Structures describes that the dynticks counter of the rcu_dynticks data structure is incremented when we transitions to or from dynticks-idle mode. However it doesn't mention that it is also incremented due to transitions to and from user mode which for dynticks purposes is an extended quiescent state. I found this with tracing calls to rcu_dynticks_eqs_enter which can also happen from rcu_user_enter. Lets add this information to the Data-Structures document. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2018-08-29doc: Fix broken RCU-requirements link to LKML archiveJoel Fernandes (Google)
Two of the Requirements.html LKML links are broken. This patch changes them to use the archive from lore.kernel.org, which works fine. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2018-08-29doc: Add design documentation on interruption of NMI handlersPaul E. McKenney
Make Requirements.html talk about how NMI handlers can take what appear to RCU to be normal interrupts. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2018-07-12doc: Update memory-ordering documentation for ->gp-seqPaul E. McKenney
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2018-07-12doc: Update data-structure documentation for ->gp_seqPaul E. McKenney
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-12-11Merge branches 'cond_resched.2017.12.04a', 'dyntick.2017.11.28a', ↵Paul E. McKenney
'fixes.2017.12.11a', 'srbd.2017.12.05a' and 'torture.2017.12.11a' into HEAD 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
2017-12-05doc: De-emphasize smp_read_barrier_dependsPaul E. McKenney
This commit keeps only the historical and low-level discussion of smp_read_barrier_depends(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Adjusted to allow for David Howells feedback on prior commit. ]
2017-12-04doc: Eliminate cond_resched_rcu_qs() in favor of cond_resched()Paul E. McKenney
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 <paulmck@linux.vnet.ibm.com>
2017-11-28doc: Update dyntick-idle design documentation for NMI/irq consolidationPaul E. McKenney
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-11-13Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "The main changes in this cycle are: - Documentation updates - RCU CPU stall-warning updates - Torture-test updates - Miscellaneous fixes Size wise the biggest updates are to documentation. Excluding documentation most of the code increase comes from a single commit which expands debugging" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) srcu: Add parameters to SRCU docbook comments doc: Rewrite confusing statement about memory barriers memory-barriers.txt: Fix typo in pairing example rcu/segcblist: Include rcupdate.h rcu: Add extended-quiescent-state testing advice rcu: Suppress lockdep false-positive ->boost_mtx complaints rcu: Do not include rtmutex_common.h unconditionally torture: Provide TMPDIR environment variable to specify tmpdir rcutorture: Dump writer stack if stalled rcutorture: Add interrupt-disable capability to stall-warning tests rcu: Suppress RCU CPU stall warnings while dumping trace rcu: Turn off tracing before dumping trace rcu: Make RCU CPU stall warnings check for irq-disabled CPUs sched,rcu: Make cond_resched() provide RCU quiescent state sched: Make resched_cpu() unconditional irq_work: Map irq_work_on_queue() to irq_work_on() in !SMP rcu: Create call_rcu_tasks() kthread at boot time rcu: Fix up pending cbs check in rcu_prepare_for_idle memory-barriers: Rework multicopy-atomicity section memory-barriers: Replace uses of "transitive" ...
2017-10-19Documentation: fix ref to workqueue contentTom Saeger
Signed-off-by: Tom Saeger <tom.saeger@oracle.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-10-09documentation: RCU grace-period memory ordering guaranteesPaul E. McKenney
This commit provides text and diagrams showing how Tree RCU implements its grace-period memory ordering guarantees. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-17doc: Set down RCU's scheduling-clock-interrupt needsPaul E. McKenney
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 <paulmck@linux.vnet.ibm.com>
2017-06-08rcu: Remove debugfs tracingPaul E. McKenney
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 <paulmck@linux.vnet.ibm.com>
2017-06-08rcu: Remove SPARSE_RCU_POINTER Kconfig optionPaul E. McKenney
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 <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Fengguang Wu <fengguang.wu@intel.com>
2017-06-08rcu: Remove nohz_full full-system-idle state machinePaul E. McKenney
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 <paulmck@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-08doc: Take tail recursion into account in RCU requirementsPaul E. McKenney
This commit classifies tail recursion as an alternative way to write a loop, with similar limitations. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-06-08srcu: Document auto-expediting requirementPaul E. McKenney
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 <paulmck@linux.vnet.ibm.com>
2017-04-21Merge branches 'doc.2017.04.12a', 'fixes.2017.04.19a' and 'srcu.2017.04.21a' ↵Paul E. McKenney
into HEAD doc.2017.04.12a: Documentation updates fixes.2017.04.19a: Miscellaneous fixes srcu.2017.04.21a: Parallelize SRCU callback handling
2017-04-18rcu: Place guard on rcu_all_qs() and rcu_note_context_switch() actionsPaul E. McKenney
The rcu_all_qs() and rcu_note_context_switch() do a series of checks, taking various actions to supply RCU with quiescent states, depending on the outcomes of the various checks. This is a bit much for scheduling fastpaths, so this commit creates a separate ->rcu_urgent_qs field in the rcu_dynticks structure that acts as a global guard for these checks. Thus, in the common case, rcu_all_qs() and rcu_note_context_switch() check the ->rcu_urgent_qs field, find it false, and simply return. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org>
2017-04-18rcu: Eliminate flavor scan in rcu_momentary_dyntick_idle()Paul E. McKenney
The rcu_momentary_dyntick_idle() function scans the RCU flavors, checking that one of them still needs a quiescent state before doing an expensive atomic operation on the ->dynticks counter. However, this check reduces overhead only after a rare race condition, and increases complexity. This commit therefore removes the scan and the mechanism enabling the scan. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18rcu: Pull rcu_qs_ctr into rcu_dynticks structurePaul E. McKenney
The rcu_qs_ctr variable is yet another isolated per-CPU variable, so this commit pulls it into the pre-existing rcu_dynticks per-CPU structure. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18rcu: Pull rcu_sched_qs_mask into rcu_dynticks structurePaul E. McKenney
The rcu_sched_qs_mask variable is yet another isolated per-CPU variable, so this commit pulls it into the pre-existing rcu_dynticks per-CPU structure. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-12doc: Update requirements based on recent changesPaul E. McKenney
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 <paulmck@linux.vnet.ibm.com>
2017-04-12doc: Update RCU data-structure documentation for rcu_segcblistPaul E. McKenney
The rcu_segcblist data structure, which contains segmented lists of RCU callbacks, was recently added. This commit updates the documentation accordingly. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-12doc: Add mid-boot operation to expedited grace periodsPaul E. McKenney
This commit adds a description of how expedited grace periods operate during the mid-boot "dead zone", which starts when the scheduler spawns the first kthread and ends when all of RCU's kthreads have been spawned. In short, before mid-boot, synchronous grace periods can be a no-op. After the end of mid-boot, workqueues may be used. During mid-boot, the requesting task drivees the expedited grace period. For more detail, see https://lwn.net/Articles/716148/. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-12doc: Synchronous RCU grace periods are now legal throughout bootPaul E. McKenney
This commit updates the "Early Boot" section of the RCU requirements to describe how synchronous RCU grace periods are now legal throughout the boot process. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-01-14doc: Quick-Quiz answers are now inlinePaul E. McKenney
Now that quick-quiz answers are inline, there is no separate section containing those answers. This commit therefore removes the dangling reference from the RCU data-structures design documentation. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2017-01-14doc: Fix RCU requirements typosTetsuo Handa
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>