From 68cb040ff7ac95f5368a49e1a8fe4440a9e563b6 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 3 Dec 2012 13:52:00 -0800 Subject: [PATCH] --- yaml --- r: 349807 b: refs/heads/master c: dc35c8934eba959b690921615fcd987e8bc17e4a h: refs/heads/master i: 349805: ca81ffead8937d4151b9cbc13ff7e4abbc5d2add 349803: 5acca182229436e97ff0ed49753d6dda3138f64b 349799: 61e95dcbcbb58b3544b878c9ec97590ec9ea19d4 349791: c3890cf42923779df7297afc9482072e75dcddd9 v: v3 --- [refs] | 2 +- trunk/include/linux/rcupdate.h | 2 +- trunk/include/trace/events/rcu.h | 6 +- trunk/kernel/context_tracking.c | 75 ++--------- trunk/kernel/rcutiny.c | 2 +- trunk/kernel/rcutorture.c | 2 +- trunk/kernel/rcutree.c | 208 +++++++++++++++++++++++++------ trunk/kernel/rcutree.h | 6 + trunk/lib/Kconfig.debug | 114 ++++++++--------- 9 files changed, 251 insertions(+), 166 deletions(-) diff --git a/[refs] b/[refs] index 3d736a48cb47..99ae187c0bfe 100644 --- a/[refs] +++ b/[refs] @@ -1,2 +1,2 @@ --- -refs/heads/master: 4eacdf18374e5d7d21a728b46dfec269ac8ef55c +refs/heads/master: dc35c8934eba959b690921615fcd987e8bc17e4a diff --git a/trunk/include/linux/rcupdate.h b/trunk/include/linux/rcupdate.h index 7e12dbaa1457..275aa3f1062d 100644 --- a/trunk/include/linux/rcupdate.h +++ b/trunk/include/linux/rcupdate.h @@ -749,7 +749,7 @@ static inline void rcu_preempt_sleep_check(void) * preemptible RCU implementations (TREE_PREEMPT_RCU and TINY_PREEMPT_RCU) * in CONFIG_PREEMPT kernel builds, RCU read-side critical sections may * be preempted, but explicit blocking is illegal. Finally, in preemptible - * RCU implementations in real-time (with -rt patchset) kernel builds, + * RCU implementations in real-time (CONFIG_PREEMPT_RT) kernel builds, * RCU read-side critical sections may be preempted and they may also * block, but only when acquiring spinlocks that are subject to priority * inheritance. diff --git a/trunk/include/trace/events/rcu.h b/trunk/include/trace/events/rcu.h index f91949850fce..d4f559b1ec34 100644 --- a/trunk/include/trace/events/rcu.h +++ b/trunk/include/trace/events/rcu.h @@ -393,7 +393,7 @@ TRACE_EVENT(rcu_kfree_callback, */ TRACE_EVENT(rcu_batch_start, - TP_PROTO(char *rcuname, long qlen_lazy, long qlen, long blimit), + TP_PROTO(char *rcuname, long qlen_lazy, long qlen, int blimit), TP_ARGS(rcuname, qlen_lazy, qlen, blimit), @@ -401,7 +401,7 @@ TRACE_EVENT(rcu_batch_start, __field(char *, rcuname) __field(long, qlen_lazy) __field(long, qlen) - __field(long, blimit) + __field(int, blimit) ), TP_fast_assign( @@ -411,7 +411,7 @@ TRACE_EVENT(rcu_batch_start, __entry->blimit = blimit; ), - TP_printk("%s CBs=%ld/%ld bl=%ld", + TP_printk("%s CBs=%ld/%ld bl=%d", __entry->rcuname, __entry->qlen_lazy, __entry->qlen, __entry->blimit) ); diff --git a/trunk/kernel/context_tracking.c b/trunk/kernel/context_tracking.c index d566aba7e801..e0e07fd55508 100644 --- a/trunk/kernel/context_tracking.c +++ b/trunk/kernel/context_tracking.c @@ -1,19 +1,3 @@ -/* - * Context tracking: Probe on high level context boundaries such as kernel - * and userspace. This includes syscalls and exceptions entry/exit. - * - * This is used by RCU to remove its dependency on the timer tick while a CPU - * runs in userspace. - * - * Started by Frederic Weisbecker: - * - * Copyright (C) 2012 Red Hat, Inc., Frederic Weisbecker - * - * Many thanks to Gilad Ben-Yossef, Paul McKenney, Ingo Molnar, Andrew Morton, - * Steven Rostedt, Peter Zijlstra for suggestions and improvements. - * - */ - #include #include #include @@ -22,8 +6,8 @@ struct context_tracking { /* - * When active is false, probes are unset in order - * to minimize overhead: TIF flags are cleared + * When active is false, hooks are not set to + * minimize overhead: TIF flags are cleared * and calls to user_enter/exit are ignored. This * may be further optimized using static keys. */ @@ -40,15 +24,6 @@ static DEFINE_PER_CPU(struct context_tracking, context_tracking) = { #endif }; -/** - * user_enter - Inform the context tracking that the CPU is going to - * enter userspace mode. - * - * This function must be called right before we switch from the kernel - * to userspace, when it's guaranteed the remaining kernel instructions - * to execute won't use any RCU read side critical section because this - * function sets RCU in extended quiescent state. - */ void user_enter(void) { unsigned long flags; @@ -64,70 +39,40 @@ void user_enter(void) if (in_interrupt()) return; - /* Kernel threads aren't supposed to go to userspace */ WARN_ON_ONCE(!current->mm); local_irq_save(flags); if (__this_cpu_read(context_tracking.active) && __this_cpu_read(context_tracking.state) != IN_USER) { __this_cpu_write(context_tracking.state, IN_USER); - /* - * At this stage, only low level arch entry code remains and - * then we'll run in userspace. We can assume there won't be - * any RCU read-side critical section until the next call to - * user_exit() or rcu_irq_enter(). Let's remove RCU's dependency - * on the tick. - */ rcu_user_enter(); } local_irq_restore(flags); } - -/** - * user_exit - Inform the context tracking that the CPU is - * exiting userspace mode and entering the kernel. - * - * This function must be called after we entered the kernel from userspace - * before any use of RCU read side critical section. This potentially include - * any high level kernel code like syscalls, exceptions, signal handling, etc... - * - * This call supports re-entrancy. This way it can be called from any exception - * handler without needing to know if we came from userspace or not. - */ void user_exit(void) { unsigned long flags; + /* + * Some contexts may involve an exception occuring in an irq, + * leading to that nesting: + * rcu_irq_enter() rcu_user_exit() rcu_user_exit() rcu_irq_exit() + * This would mess up the dyntick_nesting count though. And rcu_irq_*() + * helpers are enough to protect RCU uses inside the exception. So + * just return immediately if we detect we are in an IRQ. + */ if (in_interrupt()) return; local_irq_save(flags); if (__this_cpu_read(context_tracking.state) == IN_USER) { __this_cpu_write(context_tracking.state, IN_KERNEL); - /* - * We are going to run code that may use RCU. Inform - * RCU core about that (ie: we may need the tick again). - */ rcu_user_exit(); } local_irq_restore(flags); } - -/** - * context_tracking_task_switch - context switch the syscall callbacks - * @prev: the task that is being switched out - * @next: the task that is being switched in - * - * The context tracking uses the syscall slow path to implement its user-kernel - * boundaries probes on syscalls. This way it doesn't impact the syscall fast - * path on CPUs that don't do context tracking. - * - * But we need to clear the flag on the previous task because it may later - * migrate to some CPU that doesn't do the context tracking. As such the TIF - * flag may not be desired there. - */ void context_tracking_task_switch(struct task_struct *prev, struct task_struct *next) { diff --git a/trunk/kernel/rcutiny.c b/trunk/kernel/rcutiny.c index 9f72a0f9f85a..e7dce58f9c2a 100644 --- a/trunk/kernel/rcutiny.c +++ b/trunk/kernel/rcutiny.c @@ -193,7 +193,7 @@ EXPORT_SYMBOL(rcu_is_cpu_idle); * interrupts don't count, we must be running at the first interrupt * level. */ -static int rcu_is_cpu_rrupt_from_idle(void) +int rcu_is_cpu_rrupt_from_idle(void) { return rcu_dynticks_nesting <= 1; } diff --git a/trunk/kernel/rcutorture.c b/trunk/kernel/rcutorture.c index 0249800c6112..31dea01c85fd 100644 --- a/trunk/kernel/rcutorture.c +++ b/trunk/kernel/rcutorture.c @@ -1749,7 +1749,7 @@ static int rcu_torture_barrier_init(void) barrier_cbs_wq = kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]), GFP_KERNEL); - if (barrier_cbs_tasks == NULL || !barrier_cbs_wq) + if (barrier_cbs_tasks == NULL || barrier_cbs_wq == 0) return -ENOMEM; for (i = 0; i < n_barrier_cbs; i++) { init_waitqueue_head(&barrier_cbs_wq[i]); diff --git a/trunk/kernel/rcutree.c b/trunk/kernel/rcutree.c index 8a13c8ef9642..ac6a75d152ef 100644 --- a/trunk/kernel/rcutree.c +++ b/trunk/kernel/rcutree.c @@ -105,7 +105,7 @@ int rcu_num_nodes __read_mostly = NUM_RCU_NODES; /* Total # rcu_nodes in use. */ * The rcu_scheduler_active variable transitions from zero to one just * before the first task is spawned. So when this variable is zero, RCU * can assume that there is but one task, allowing RCU to (for example) - * optimize synchronize_sched() to a simple barrier(). When this variable + * optimized synchronize_sched() to a simple barrier(). When this variable * is one, RCU must actually do all the hard work required to detect real * grace periods. This variable is also used to suppress boot-time false * positives from lockdep-RCU error checking. @@ -305,17 +305,27 @@ cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) } /* - * Does the current CPU require a yet-as-unscheduled grace period? + * Does the current CPU require a not-yet-started grace period? + * The caller must have disabled interrupts to prevent races with + * normal callback registry. */ static int cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) { - struct rcu_head **ntp; + int i; - ntp = rdp->nxttail[RCU_DONE_TAIL + - (ACCESS_ONCE(rsp->completed) != rdp->completed)]; - return rdp->nxttail[RCU_DONE_TAIL] && ntp && *ntp && - !rcu_gp_in_progress(rsp); + if (rcu_gp_in_progress(rsp)) + return 0; /* No, a grace period is already in progress. */ + if (!rdp->nxttail[RCU_NEXT_TAIL]) + return 0; /* No, this is a no-CBs (or offline) CPU. */ + if (*rdp->nxttail[RCU_NEXT_READY_TAIL]) + return 1; /* Yes, this CPU has newly registered callbacks. */ + for (i = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++) + if (rdp->nxttail[i - 1] != rdp->nxttail[i] && + ULONG_CMP_LT(ACCESS_ONCE(rsp->completed), + rdp->nxtcompleted[i])) + return 1; /* Yes, CBs for future grace period. */ + return 0; /* No grace period needed. */ } /* @@ -336,7 +346,7 @@ static struct rcu_node *rcu_get_root(struct rcu_state *rsp) static void rcu_eqs_enter_common(struct rcu_dynticks *rdtp, long long oldval, bool user) { - trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting); + trace_rcu_dyntick("Start", oldval, 0); if (!user && !is_idle_task(current)) { struct task_struct *idle = idle_task(smp_processor_id()); @@ -727,7 +737,7 @@ EXPORT_SYMBOL_GPL(rcu_lockdep_current_cpu_online); * interrupt from idle, return true. The caller must have at least * disabled preemption. */ -static int rcu_is_cpu_rrupt_from_idle(void) +int rcu_is_cpu_rrupt_from_idle(void) { return __get_cpu_var(rcu_dynticks).dynticks_nesting <= 1; } @@ -1070,6 +1080,139 @@ static void init_callback_list(struct rcu_data *rdp) init_nocb_callback_list(rdp); } +/* + * Determine the value that ->completed will have at the end of the + * next subsequent grace period. This is used to tag callbacks so that + * a CPU can invoke callbacks in a timely fashion even if that CPU has + * been dyntick-idle for an extended period with callbacks under the + * influence of RCU_FAST_NO_HZ. + * + * The caller must hold rnp->lock with interrupts disabled. + */ +static unsigned long rcu_cbs_completed(struct rcu_state *rsp, + struct rcu_node *rnp) +{ + /* + * If RCU is idle, we just wait for the next grace period. + * But we can only be sure that RCU is idle if we are looking + * at the root rcu_node structure -- otherwise, a new grace + * period might have started, but just not yet gotten around + * to initializing the current non-root rcu_node structure. + */ + if (rcu_get_root(rsp) == rnp && rnp->gpnum == rnp->completed) + return rnp->completed + 1; + + /* + * Otherwise, wait for a possible partial grace period and + * then the subsequent full grace period. + */ + return rnp->completed + 2; +} + +/* + * If there is room, assign a ->completed number to any callbacks on + * this CPU that have not already been assigned. Also accelerate any + * callbacks that were previously assigned a ->completed number that has + * since proven to be too conservative, which can happen if callbacks get + * assigned a ->completed number while RCU is idle, but with reference to + * a non-root rcu_node structure. This function is idempotent, so it does + * not hurt to call it repeatedly. + * + * The caller must hold rnp->lock with interrupts disabled. + */ +static void rcu_accelerate_cbs(struct rcu_state *rsp, struct rcu_node *rnp, + struct rcu_data *rdp) +{ + unsigned long c; + int i; + + /* If the CPU has no callbacks, nothing to do. */ + if (!rdp->nxttail[RCU_NEXT_TAIL] || !*rdp->nxttail[RCU_DONE_TAIL]) + return; + + /* + * Starting from the sublist containing the callbacks most + * recently assigned a ->completed number and working down, find the + * first sublist that is not assignable to an upcoming grace period. + * Such a sublist has something in it (first two tests) and has + * a ->completed number assigned that will complete sooner than + * the ->completed number for newly arrived callbacks (last test). + * + * The key point is that any later sublist can be assigned the + * same ->completed number as the newly arrived callbacks, which + * means that the callbacks in any of these later sublist can be + * grouped into a single sublist, whether or not they have already + * been assigned a ->completed number. + */ + c = rcu_cbs_completed(rsp, rnp); + for (i = RCU_NEXT_TAIL - 1; i > RCU_DONE_TAIL; i--) + if (rdp->nxttail[i] != rdp->nxttail[i - 1] && + !ULONG_CMP_GE(rdp->nxtcompleted[i], c)) + break; + + /* + * If there are no sublist for unassigned callbacks, leave. + * At the same time, advance "i" one sublist, so that "i" will + * index into the sublist where all the remaining callbacks should + * be grouped into. + */ + if (++i >= RCU_NEXT_TAIL) + return; + + /* + * Assign all subsequent callbacks' ->completed number to the next + * full grace period and group them all in the sublist initially + * indexed by "i". + */ + for (; i <= RCU_NEXT_TAIL; i++) { + rdp->nxttail[i] = rdp->nxttail[RCU_NEXT_TAIL]; + rdp->nxtcompleted[i] = c; + } +} + +/* + * Move any callbacks whose grace period has completed to the + * RCU_DONE_TAIL sublist, then compact the remaining sublists and + * assign ->completed numbers to any callbacks in the RCU_NEXT_TAIL + * sublist. This function is idempotent, so it does not hurt to + * invoke it repeatedly. As long as it is not invoked -too- often... + * + * The caller must hold rnp->lock with interrupts disabled. + */ +static void rcu_advance_cbs(struct rcu_state *rsp, struct rcu_node *rnp, + struct rcu_data *rdp) +{ + int i, j; + + /* If the CPU has no callbacks, nothing to do. */ + if (!rdp->nxttail[RCU_NEXT_TAIL] || !*rdp->nxttail[RCU_DONE_TAIL]) + return; + + /* + * Find all callbacks whose ->completed numbers indicate that they + * are ready to invoke, and put them into the RCU_DONE_TAIL sublist. + */ + for (i = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++) { + if (ULONG_CMP_LT(rnp->completed, rdp->nxtcompleted[i])) + break; + rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[i]; + } + /* Clean up any sublist tail pointers that were misordered above. */ + for (j = RCU_WAIT_TAIL; j < i; j++) + rdp->nxttail[j] = rdp->nxttail[RCU_DONE_TAIL]; + + /* Copy down callbacks to fill in empty sublists. */ + for (j = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++, j++) { + if (rdp->nxttail[j] == rdp->nxttail[RCU_NEXT_TAIL]) + break; + rdp->nxttail[j] = rdp->nxttail[i]; + rdp->nxtcompleted[j] = rdp->nxtcompleted[i]; + } + + /* Classify any remaining callbacks. */ + rcu_accelerate_cbs(rsp, rnp, rdp); +} + /* * Advance this CPU's callbacks, but only if the current grace period * has ended. This may be called only from the CPU to whom the rdp @@ -1080,12 +1223,15 @@ static void __rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) { /* Did another grace period end? */ - if (rdp->completed != rnp->completed) { + if (rdp->completed == rnp->completed) { + + /* No, so just accelerate recent callbacks. */ + rcu_accelerate_cbs(rsp, rnp, rdp); + + } else { - /* Advance callbacks. No harm if list empty. */ - rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL]; - rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL]; - rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; + /* Advance callbacks. */ + rcu_advance_cbs(rsp, rnp, rdp); /* Remember that we saw this grace-period completion. */ rdp->completed = rnp->completed; @@ -1392,17 +1538,10 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) /* * Because there is no grace period in progress right now, * any callbacks we have up to this point will be satisfied - * by the next grace period. So promote all callbacks to be - * handled after the end of the next grace period. If the - * CPU is not yet aware of the end of the previous grace period, - * we need to allow for the callback advancement that will - * occur when it does become aware. Deadlock prevents us from - * making it aware at this point: We cannot acquire a leaf - * rcu_node ->lock while holding the root rcu_node ->lock. + * by the next grace period. So this is a good place to + * assign a grace period number to recently posted callbacks. */ - rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; - if (rdp->completed == rsp->completed) - rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; + rcu_accelerate_cbs(rsp, rnp, rdp); rsp->gp_flags = RCU_GP_FLAG_INIT; raw_spin_unlock(&rnp->lock); /* Interrupts remain disabled. */ @@ -1527,7 +1666,7 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp) * This GP can't end until cpu checks in, so all of our * callbacks can be processed during the next GP. */ - rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; + rcu_accelerate_cbs(rsp, rnp, rdp); rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */ } @@ -1779,7 +1918,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) long bl, count, count_lazy; int i; - /* If no callbacks are ready, just return.*/ + /* If no callbacks are ready, just return. */ if (!cpu_has_callbacks_ready_to_invoke(rdp)) { trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, 0); trace_rcu_batch_end(rsp->name, 0, !!ACCESS_ONCE(rdp->nxtlist), @@ -2008,19 +2147,19 @@ __rcu_process_callbacks(struct rcu_state *rsp) WARN_ON_ONCE(rdp->beenonline == 0); - /* - * Advance callbacks in response to end of earlier grace - * period that some other CPU ended. - */ + /* Handle the end of a grace period that some other CPU ended. */ rcu_process_gp_end(rsp, rdp); /* Update RCU state based on any recent quiescent states. */ rcu_check_quiescent_state(rsp, rdp); /* Does this CPU require a not-yet-started grace period? */ + local_irq_save(flags); if (cpu_needs_another_gp(rsp, rdp)) { - raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags); + raw_spin_lock(&rcu_get_root(rsp)->lock); /* irqs disabled. */ rcu_start_gp(rsp, flags); /* releases above lock */ + } else { + local_irq_restore(flags); } /* If there are callbacks ready, invoke them. */ @@ -2719,6 +2858,9 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) rdp->dynticks = &per_cpu(rcu_dynticks, cpu); WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE); WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1); +#ifdef CONFIG_RCU_USER_QS + WARN_ON_ONCE(rdp->dynticks->in_user); +#endif rdp->cpu = cpu; rdp->rsp = rsp; rcu_boot_init_nocb_percpu_data(rdp); @@ -2935,10 +3077,6 @@ static void __init rcu_init_one(struct rcu_state *rsp, BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */ - /* Silence gcc 4.8 warning about array index out of range. */ - if (rcu_num_lvls > RCU_NUM_LVLS) - panic("rcu_init_one: rcu_num_lvls overflow"); - /* Initialize the level-tracking arrays. */ for (i = 0; i < rcu_num_lvls; i++) diff --git a/trunk/kernel/rcutree.h b/trunk/kernel/rcutree.h index 6f21f2eccb16..c9f362e9b13d 100644 --- a/trunk/kernel/rcutree.h +++ b/trunk/kernel/rcutree.h @@ -102,6 +102,10 @@ struct rcu_dynticks { /* idle-period nonlazy_posted snapshot. */ int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */ #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ +#ifdef CONFIG_RCU_USER_QS + bool ignore_user_qs; /* Treat userspace as extended QS or not */ + bool in_user; /* Is the CPU in userland from RCU POV? */ +#endif }; /* RCU's kthread states for tracing. */ @@ -278,6 +282,8 @@ struct rcu_data { */ struct rcu_head *nxtlist; struct rcu_head **nxttail[RCU_NEXT_SIZE]; + unsigned long nxtcompleted[RCU_NEXT_SIZE]; + /* grace periods for sublists. */ long qlen_lazy; /* # of lazy queued callbacks */ long qlen; /* # of queued callbacks, incl lazy */ long qlen_last_fqs_check; diff --git a/trunk/lib/Kconfig.debug b/trunk/lib/Kconfig.debug index 122db3d323c8..3a353091a903 100644 --- a/trunk/lib/Kconfig.debug +++ b/trunk/lib/Kconfig.debug @@ -605,6 +605,61 @@ config PROVE_LOCKING For more details, see Documentation/lockdep-design.txt. +config PROVE_RCU + bool "RCU debugging: prove RCU correctness" + depends on PROVE_LOCKING + default n + help + This feature enables lockdep extensions that check for correct + use of RCU APIs. This is currently under development. Say Y + if you want to debug RCU usage or help work on the PROVE_RCU + feature. + + Say N if you are unsure. + +config PROVE_RCU_REPEATEDLY + bool "RCU debugging: don't disable PROVE_RCU on first splat" + depends on PROVE_RCU + default n + help + By itself, PROVE_RCU will disable checking upon issuing the + first warning (or "splat"). This feature prevents such + disabling, allowing multiple RCU-lockdep warnings to be printed + on a single reboot. + + Say Y to allow multiple RCU-lockdep warnings per boot. + + Say N if you are unsure. + +config PROVE_RCU_DELAY + bool "RCU debugging: preemptible RCU race provocation" + depends on DEBUG_KERNEL && PREEMPT_RCU + default n + help + There is a class of races that involve an unlikely preemption + of __rcu_read_unlock() just after ->rcu_read_lock_nesting has + been set to INT_MIN. This feature inserts a delay at that + point to increase the probability of these races. + + Say Y to increase probability of preemption of __rcu_read_unlock(). + + Say N if you are unsure. + +config SPARSE_RCU_POINTER + bool "RCU debugging: sparse-based checks for pointer usage" + default n + help + This feature enables the __rcu sparse annotation for + RCU-protected pointers. This annotation will cause sparse + to flag any non-RCU used of annotated pointers. This can be + helpful when debugging RCU usage. Please note that this feature + is not intended to enforce code cleanliness; it is instead merely + a debugging aid. + + Say Y to make sparse flag questionable use of RCU-protected pointers + + Say N if you are unsure. + config LOCKDEP bool depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT @@ -882,63 +937,6 @@ config BOOT_PRINTK_DELAY BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect what it believes to be lockup conditions. -menu "RCU Debugging" - -config PROVE_RCU - bool "RCU debugging: prove RCU correctness" - depends on PROVE_LOCKING - default n - help - This feature enables lockdep extensions that check for correct - use of RCU APIs. This is currently under development. Say Y - if you want to debug RCU usage or help work on the PROVE_RCU - feature. - - Say N if you are unsure. - -config PROVE_RCU_REPEATEDLY - bool "RCU debugging: don't disable PROVE_RCU on first splat" - depends on PROVE_RCU - default n - help - By itself, PROVE_RCU will disable checking upon issuing the - first warning (or "splat"). This feature prevents such - disabling, allowing multiple RCU-lockdep warnings to be printed - on a single reboot. - - Say Y to allow multiple RCU-lockdep warnings per boot. - - Say N if you are unsure. - -config PROVE_RCU_DELAY - bool "RCU debugging: preemptible RCU race provocation" - depends on DEBUG_KERNEL && PREEMPT_RCU - default n - help - There is a class of races that involve an unlikely preemption - of __rcu_read_unlock() just after ->rcu_read_lock_nesting has - been set to INT_MIN. This feature inserts a delay at that - point to increase the probability of these races. - - Say Y to increase probability of preemption of __rcu_read_unlock(). - - Say N if you are unsure. - -config SPARSE_RCU_POINTER - bool "RCU debugging: sparse-based checks for pointer usage" - default n - help - This feature enables the __rcu sparse annotation for - RCU-protected pointers. This annotation will cause sparse - to flag any non-RCU used of annotated pointers. This can be - helpful when debugging RCU usage. Please note that this feature - is not intended to enforce code cleanliness; it is instead merely - a debugging aid. - - Say Y to make sparse flag questionable use of RCU-protected pointers - - Say N if you are unsure. - config RCU_TORTURE_TEST tristate "torture tests for RCU" depends on DEBUG_KERNEL @@ -1017,8 +1015,6 @@ config RCU_TRACE Say Y here if you want to enable RCU tracing Say N if you are unsure. -endmenu # "RCU Debugging" - config KPROBES_SANITY_TEST bool "Kprobes sanity tests" depends on DEBUG_KERNEL