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2019-03-06Merge branch 'perf-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf updates from Ingo Molnar: "Lots of tooling updates - too many to list, here's a few highlights: - Various subcommand updates to 'perf trace', 'perf report', 'perf record', 'perf annotate', 'perf script', 'perf test', etc. - CPU and NUMA topology and affinity handling improvements, - HW tracing and HW support updates: - Intel PT updates - ARM CoreSight updates - vendor HW event updates - BPF updates - Tons of infrastructure updates, both on the build system and the library support side - Documentation updates. - ... and lots of other changes, see the changelog for details. Kernel side updates: - Tighten up kprobes blacklist handling, reduce the number of places where developers can install a kprobe and hang/crash the system. - Fix/enhance vma address filter handling. - Various PMU driver updates, small fixes and additions. - refcount_t conversions - BPF updates - error code propagation enhancements - misc other changes" * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (238 commits) perf script python: Add Python3 support to syscall-counts-by-pid.py perf script python: Add Python3 support to syscall-counts.py perf script python: Add Python3 support to stat-cpi.py perf script python: Add Python3 support to stackcollapse.py perf script python: Add Python3 support to sctop.py perf script python: Add Python3 support to powerpc-hcalls.py perf script python: Add Python3 support to net_dropmonitor.py perf script python: Add Python3 support to mem-phys-addr.py perf script python: Add Python3 support to failed-syscalls-by-pid.py perf script python: Add Python3 support to netdev-times.py perf tools: Add perf_exe() helper to find perf binary perf script: Handle missing fields with -F +.. perf data: Add perf_data__open_dir_data function perf data: Add perf_data__(create_dir|close_dir) functions perf data: Fail check_backup in case of error perf data: Make check_backup work over directories perf tools: Add rm_rf_perf_data function perf tools: Add pattern name checking to rm_rf perf tools: Add depth checking to rm_rf perf data: Add global path holder ...
2019-03-05Merge 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 RCU related changes in this cycle were: - Additional cleanups after RCU flavor consolidation - Grace-period forward-progress cleanups and improvements - Documentation updates - Miscellaneous fixes - spin_is_locked() conversions to lockdep - SPDX changes to RCU source and header files - SRCU updates - Torture-test updates, including nolibc updates and moving nolibc to tools/include" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (71 commits) locking/locktorture: Convert to SPDX license identifier linux/torture: Convert to SPDX license identifier torture: Convert to SPDX license identifier linux/srcu: Convert to SPDX license identifier linux/rcutree: Convert to SPDX license identifier linux/rcutiny: Convert to SPDX license identifier linux/rcu_sync: Convert to SPDX license identifier linux/rcu_segcblist: Convert to SPDX license identifier linux/rcupdate: Convert to SPDX license identifier linux/rcu_node_tree: Convert to SPDX license identifier rcu/update: Convert to SPDX license identifier rcu/tree: Convert to SPDX license identifier rcu/tiny: Convert to SPDX license identifier rcu/sync: Convert to SPDX license identifier rcu/srcu: Convert to SPDX license identifier rcu/rcutorture: Convert to SPDX license identifier rcu/rcu_segcblist: Convert to SPDX license identifier rcu/rcuperf: Convert to SPDX license identifier rcu/rcu.h: Convert to SPDX license identifier RCU/torture.txt: Remove section MODULE PARAMETERS ...
2019-02-13kprobes: Prohibit probing on RCU debug routineMasami Hiramatsu
Since kprobe itself depends on RCU, probing on RCU debug routine can cause recursive breakpoint bugs. Prohibit probing on RCU debug routines. int3 ->do_int3() ->ist_enter() ->RCU_LOCKDEP_WARN() ->debug_lockdep_rcu_enabled() -> int3 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andrea Righi <righi.andrea@gmail.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/154998807741.31052.11229157537816341591.stgit@devbox Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-13x86/kprobes: Prohibit probing on functions before kprobe_int3_handler()Masami Hiramatsu
Prohibit probing on the functions called before kprobe_int3_handler() in do_int3(). More specifically, ftrace_int3_handler(), poke_int3_handler(), and ist_enter(). And since rcu_nmi_enter() is called by ist_enter(), it also should be marked as NOKPROBE_SYMBOL. Since those are handled before kprobe_int3_handler(), probing those functions can cause a breakpoint recursion and crash the kernel. Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andrea Righi <righi.andrea@gmail.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/154998793571.31052.11301258949601150994.stgit@devbox Signed-off-by: Ingo Molnar <mingo@kernel.org>
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.
2019-02-09rcu/update: Convert to SPDX license identifierPaul E. McKenney
Replace the license boiler plate with a SPDX license identifier. While in the area, update an email address. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09rcu/tree: Convert to SPDX license identifierPaul E. McKenney
Replace the license boiler plate with a SPDX license identifier. While in the area, update an email address. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> [ paulmck: Update .h file SPDX comment format per Joe Perches. ] Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09rcu/tiny: Convert to SPDX license identifierPaul E. McKenney
Replace the license boiler plate with a SPDX license identifier. While in the area, update an email address. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09rcu/sync: Convert to SPDX license identifierPaul E. McKenney
Replace the license boiler plate with a SPDX license identifier. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09rcu/srcu: Convert to SPDX license identifierPaul E. McKenney
Replace the license boiler plate with a SPDX license identifier. While in the area, update an email address. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09rcu/rcutorture: Convert to SPDX license identifierPaul E. McKenney
Replace the license boiler plate with a SPDX license identifier. While in the area, update an email address. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09rcu/rcu_segcblist: Convert to SPDX license identifierPaul E. McKenney
Replace the license boiler plate with a SPDX license identifier. While in the area, update an email address. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09rcu/rcuperf: Convert to SPDX license identifierPaul E. McKenney
Replace the license boiler plate with a SPDX license identifier. While in the area, update an email address. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-02-09rcu/rcu.h: Convert to SPDX license identifierPaul E. McKenney
Replace the license boiler plate with a SPDX license identifier. While in the area, update an email address. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2019-01-25rcuperf: Stop abusing IS_ENABLED()Paul E. McKenney
The ever-evolving IS_ENABLED() macro is intended for CONFIG_* Kconfig options, but rcuperf currently uses it for the decidedly non-CONFIG_* MODULE macro. In the spirit of not inviting trouble, this commit substitutes tried-and-true #ifdef. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Acked-by: Ingo Molnar <mingo@kernel.org>
2019-01-25rcutorture: Add grace period after CPU offlinePaul E. McKenney
Beyond a certain point in the CPU-hotplug offline process, timers get stranded on the outgoing CPU, and won't fire until that CPU comes back online, which might well be never. This commit therefore adds a hook in torture_onoff_init() that is invoked from torture_offline(), which rcutorture uses to occasionally wait for a grace period. This should result in failures for RCU implementations that rely on stranded timers eventually firing in the absence of the CPU coming back online. Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcutorture: Record grace periods in forward-progress histogramPaul E. McKenney
This commit records grace periods in rcutorture's n_launders_hist[] histogram, thus allowing rcu_torture_fwd_cb_hist() to print out the elapsed number of grace periods between buckets. This information helps to determine whether a lack of forward progress is due to stalled grace periods on the one hand or due to sluggish callback invocation on the other. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25srcu: Remove srcu_queue_delayed_work_on()Sebastian Andrzej Siewior
srcu_queue_delayed_work_on() disables preemption (and therefore CPU hotplug in RCU's case) and then checks based on its own accounting if a CPU is online. If the CPU is online it uses queue_delayed_work_on() otherwise it fallbacks to queue_delayed_work(). The problem here is that queue_work() on -RT does not work with disabled preemption. queue_work_on() works also on an offlined CPU. queue_delayed_work_on() has the problem that it is possible to program a timer on an offlined CPU. This timer will fire once the CPU is online again. But until then, the timer remains programmed and nothing will happen. Add a local timer which will fire (as requested per delay) on the local CPU and then enqueue the work on the specific CPU. RCUtorture testing with SRCU-P for 24h showed no problems. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Fix obsolete DYNTICK_IRQ_NONIDLE commentPaul E. McKenney
This commit updates the DYNTICK_IRQ_NONIDLE header comment to remove the obsolete commentary about unmatched rcu_irq_{enter,exit}(). Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Repair rcu_nmi_exit() docbook headerPaul E. McKenney
This commit removes the "@irq" argument from the rcu_nmi_exit() docbook header, given that this function now has no arguments. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Remove preemption disabling from expedited CPU selectionPaul E. McKenney
It turns out that it is queue_delayed_work_on() rather than queue_work_on() that has difficulties when used concurrently with CPU-hotplug removal operations. It is therefore unnecessary to protect CPU identification and queue_work_on() with preempt_disable(). This commit therefore removes the preempt_disable() and preempt_enable() from sync_rcu_exp_select_cpus(), which has the further benefit of reducing the number of changes that must be maintained in the -rt patchset. Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Sebastian Siewior <bigeasy@linutronix.de> Suggested-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
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>
2019-01-25Merge branches 'consolidate.2019.01.26a' and 'fwd.2019.01.26a' into HEADPaul E. McKenney
consolidate.2019.01.26a: RCU flavor consolidation cleanups. fwd.2019.01.26a: RCU grace-period forward-progress fixes.
2019-01-25rcu: Prevent needless ->gp_seq_needed update in __note_gp_changes()Zhang, Jun
Currently, __note_gp_changes() checks to see if the rcu_node structure's ->gp_seq_needed is greater than or equal to that of the rcu_data structure, and if so, updates the rcu_data structure's ->gp_seq_needed field. This results in a useless store in the case where the two fields are equal. This commit therefore carries out this store only in the case where the rcu_node structure's ->gp_seq_needed is strictly greater than that of the rcu_data structure. Signed-off-by: "Zhang, Jun" <jun.zhang@intel.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Link: https://lkml.kernel.org/r/88DC34334CA3444C85D647DBFA962C2735AD5F77@SHSMSX104.ccr.corp.intel.com
2019-01-25rcu: Do RCU GP kthread self-wakeup from softirq and interruptZhang, Jun
The rcu_gp_kthread_wake() function is invoked when it might be necessary to wake the RCU grace-period kthread. Because self-wakeups are normally a useless waste of CPU cycles, if rcu_gp_kthread_wake() is invoked from this kthread, it naturally refuses to do the wakeup. Unfortunately, natural though it might be, this heuristic fails when rcu_gp_kthread_wake() is invoked from an interrupt or softirq handler that interrupted the grace-period kthread just after the final check of the wait-event condition but just before the schedule() call. In this case, a wakeup is required, even though the call to rcu_gp_kthread_wake() is within the RCU grace-period kthread's context. Failing to provide this wakeup can result in grace periods failing to start, which in turn results in out-of-memory conditions. This race window is quite narrow, but it actually did happen during real testing. It would of course need to be fixed even if it was strictly theoretical in nature. This patch does not Cc stable because it does not apply cleanly to earlier kernel versions. Fixes: 48a7639ce80c ("rcu: Make callers awaken grace-period kthread") Reported-by: "He, Bo" <bo.he@intel.com> Co-developed-by: "Zhang, Jun" <jun.zhang@intel.com> Co-developed-by: "He, Bo" <bo.he@intel.com> Co-developed-by: "xiao, jin" <jin.xiao@intel.com> Co-developed-by: Bai, Jie A <jie.a.bai@intel.com> Signed-off: "Zhang, Jun" <jun.zhang@intel.com> Signed-off: "He, Bo" <bo.he@intel.com> Signed-off: "xiao, jin" <jin.xiao@intel.com> Signed-off: Bai, Jie A <jie.a.bai@intel.com> Signed-off-by: "Zhang, Jun" <jun.zhang@intel.com> [ paulmck: Switch from !in_softirq() to "!in_interrupt() && !in_serving_softirq() to avoid redundant wakeups and to also handle the interrupt-handler scenario as well as the softirq-handler scenario that actually occurred in testing. ] Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Link: https://lkml.kernel.org/r/CD6925E8781EFD4D8E11882D20FC406D52A11F61@SHSMSX104.ccr.corp.intel.com
2019-01-25rcu: Add sysrq rcu_node-dump capabilityPaul E. McKenney
Life is hard if RCU manages to get stuck without triggering RCU CPU stall warnings or triggering the rcu_check_gp_start_stall() checks for failing to start a grace period. This commit therefore adds a boot-time-selectable sysrq key (commandeering "y") that allows manually dumping Tree RCU state. The new rcutree.sysrq_rcu kernel boot parameter must be set for this sysrq to be available. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Protect rcu_check_gp_kthread_starvation() access to ->gp_flagsPaul E. McKenney
The rcu_check_gp_kthread_starvation() function can be invoked without holding locks, so the access to the rcu_state structure's ->gp_flags field must be protected with READ_ONCE(). This commit therefore adds this protection. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Improve diagnostics for failed RCU grace-period startPaul E. McKenney
If a grace period fails to start (for example, because you commented out the last two lines of rcu_accelerate_cbs_unlocked()), rcu_core() will invoke rcu_check_gp_start_stall(), which will notice and complain. However, this complaint is lacking crucial debugging information such as when the last wakeup executed and what the value of ->gp_seq was at that time. This commit therefore removes the current pr_alert() from rcu_check_gp_start_stall(), instead invoking show_rcu_gp_kthreads(), which has been updated to print the needed information, which is collected by rcu_gp_kthread_wake(). Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Update NOCB commentsPaul E. McKenney
This commit updates a few obsolete comments in the RCU callback-offload code. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Remove unused rcu_cpu_kthread_cpu per-CPU variablePaul E. McKenney
The rcu_cpu_kthread_cpu used to provide debugfs information, but is no longer used. This commit therefore removes it. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Move rcu_cpu_has_work to rcu_data structurePaul E. McKenney
Given that RCU has a perfectly good per-CPU rcu_data structure, most per-CPU quantities should be stored there. This commit therefore moves the rcu_cpu_has_work per-CPU variable to the rcu_data structure. This also makes this variable unconditionally present, which should be acceptable given the memory reduction due to the RCU flavor consolidation and also due to simplifications this will enable. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Remove unused rcu_cpu_kthread_loops per-CPU variablePaul E. McKenney
The rcu_cpu_kthread_loops variable used to provide debugfs information, but is no longer used. This commit therefore removes it. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Move rcu_cpu_kthread_status to rcu_data structurePaul E. McKenney
Given that RCU has a perfectly good per-CPU rcu_data structure, most per-CPU quantities should be stored there. This commit therefore moves the rcu_cpu_kthread_status per-CPU variable to the rcu_data structure. This also makes this variable unconditionally present, which should be acceptable given the memory reduction due to the RCU flavor consolidation and also due to simplifications this will enable. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Move rcu_cpu_kthread_task to rcu_data structurePaul E. McKenney
Given that RCU has a perfectly good per-CPU rcu_data structure, most per-CPU quantities should be stored there. This commit therefore moves the rcu_cpu_kthread_task per-CPU variable to the rcu_data structure. This also makes this variable unconditionally present, which should be acceptable given the memory reduction due to the RCU flavor consolidation and also due to simplifications this will enable. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Accommodate zero jiffies_till_first_fqs and kthread kickingPaul E. McKenney
It is perfectly fine to set the rcutree.jiffies_till_first_fqs boot parameter to zero, in fact, this can be useful on specialty systems that usually have at least one idle CPU and that need fast grace periods. This is because this setting causes the RCU grace-period kthread to scan for idle threads immediately after grace-period initialization, as opposed to waiting several jiffies to do so. It is also perfectly fine to set the rcutree.rcu_kick_kthreads kernel parameter, which gives the RCU grace-period kthread an extra wakeup if it doesn't make progress for a period of three times the setting of the rcutree.jiffies_till_first_fqs boot parameter. This is of course problematic when the value of this parameter is zero, as it can result in unnecessary wakeup IPIs along with unnecessary WARN_ONCE() invocations. This commit therefore defers kthread kicking for at least two jiffies, regardless of the setting of rcutree.jiffies_till_first_fqs. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Discard separate per-CPU callback countsPaul E. McKenney
Back when there were multiple flavors of RCU, it was necessary to separately count lazy and non-lazy callbacks for each CPU. These counts were used in CONFIG_RCU_FAST_NO_HZ kernels to determine how long a newly idle CPU should be allowed to sleep before handling its RCU callbacks. But now that there is only one flavor, the callback counts for a given CPU's sole rcu_data structure are the counts for that CPU. This commit therefore removes the rcu_data structure's ->nonlazy_posted and ->nonlazy_posted_snap fields, the rcu_idle_count_callbacks_posted() and rcu_cpu_has_callbacks() functions, repurposes the rcu_data structure's ->all_lazy field to record the laziness state at the beginning of the latest idle sojourn, and modifies CONFIG_RCU_FAST_NO_HZ RCU CPU stall warnings accordingly. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Inline _synchronize_rcu_expedited() into synchronize_rcu_expedited()Paul E. McKenney
Now that _synchronize_rcu_expedited() has only one caller, and given that this is a tail call, this commit inlines _synchronize_rcu_expedited() into synchronize_rcu_expedited(). Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Consolidate PREEMPT and !PREEMPT synchronize_rcu()Paul E. McKenney
Now that rcu_blocking_is_gp() makes the correct immediate-return decision for both PREEMPT and !PREEMPT, a single implementation of synchronize_rcu() will work correctly under both configurations. This commit therefore eliminates a few lines of code by consolidating the two implementations of synchronize_rcu(). Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Consolidate PREEMPT and !PREEMPT synchronize_rcu_expedited()Paul E. McKenney
The CONFIG_PREEMPT=n and CONFIG_PREEMPT=y implementations of synchronize_rcu_expedited() are quite similar, and with small modifications to rcu_blocking_is_gp() can be made identical. This commit therefore makes this change in order to save a few lines of code and to reduce the amount of duplicate code. 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>
2019-01-25rcu: Inline rcu_kthread_do_work() into its sole remaining callerPaul E. McKenney
The rcu_kthread_do_work() function has a single-line body and only one remaining caller. This commit therefore saves a few lines of code by inlining rcu_kthread_do_work() into its sole remaining caller. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Eliminate RCU_BH_FLAVOR and RCU_SCHED_FLAVORPaul E. McKenney
Now that the RCU flavors have been consolidated, RCU_BH_FLAVOR and RCU_SCHED_FLAVOR are no longer used. This commit therefore saves a few lines by removing them. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Inline force_quiescent_state() into rcu_force_quiescent_state()Paul E. McKenney
Given that rcu_force_quiescent_state() is a simple wrapper around force_quiescent_state(), this commit saves a few lines of code by inlining force_quiescent_state() into rcu_force_quiescent_state(), and changing all references to force_quiescent_state() to instead invoke rcu_force_quiescent_state(). Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Make expedited IPI handler return after handling critical sectionPaul E. McKenney
During expedited RCU grace-period initialization, IPIs are sent to all non-idle online CPUs. The IPI handler checks to see if the CPU is in quiescent state, reporting one if so. This handler looks at three different cases: (1) The CPU is not in an rcu_read_lock()-based critical section, (2) The CPU is in the process of exiting an rcu_read_lock()-based critical section, and (3) The CPU is in an rcu_read_lock()-based critical section. In case (2), execution falls through into case (3). This is harmless from a functionality viewpoint, but can result in needless overhead during an improbable corner case. This commit therefore adds the "return" statement needed to prevent fall-through. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Rename and comment changes due to only one rcuo kthread per CPUPaul E. McKenney
Given RCU flavor consolidation, the name rcu_spawn_all_nocb_kthreads() is quite misleading. It no longer ever creates more than one kthread, and it does so only for the specified CPU. This commit therefore changes this name to the more descriptive rcu_spawn_cpu_nocb_kthread(), and also fixes up a similar issue in its header comment while in the area. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-15time: Move CONTEXT_TRACKING to kernel/time/KconfigPaul E. McKenney
Both CONTEXT_TRACKING and CONTEXT_TRACKING_FORCE are currently defined in kernel/rcu/kconfig, which might have made sense at some point, but no longer does given that RCU refers to neither of these Kconfig options. Therefore move them to kernel/time/Kconfig, where the rest of the NO_HZ_FULL Kconfig options live. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: https://lkml.kernel.org/r/20181220170525.GA12579@linux.ibm.com
2018-12-01rcutorture: Don't do busted forward-progress testingPaul E. McKenney
The "busted" rcutorture type is an intentionally broken implementation of RCU. Doing forward-progress testing on this implementation is not particularly meaningful on the one hand and can result in fatal abuse of the memory allocator on the other. This commit therefore disables forward-progress testing of the "busted" rcutorture type. Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-12-01rcutorture: Use 100ms buckets for forward-progress callback histogramsPaul E. McKenney
This commit narrows the scope of each bucket of the forward-progress callback-invocation histograms from one second to 100 milliseconds, which aids debugging of forward-progress problems by making shorter-duration callback-invocation stalls visible. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-12-01rcutorture: Recover from OOM during forward-progress testsPaul E. McKenney
This commit causes the OOM handler to do rcu_barrier() calls and to free up forward-progress callbacks in order to recover from OOM events. The current test is terminated, but subsequent forward-progress tests can proceed. This allows a long test to result in multiple forward-progress failures, greatly reducing the required testing time. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>