diff options
Diffstat (limited to 'debian/patches-rt/0158-rcu-Merge-RCU-bh-into-RCU-preempt.patch')
| -rw-r--r-- | debian/patches-rt/0158-rcu-Merge-RCU-bh-into-RCU-preempt.patch | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/debian/patches-rt/0158-rcu-Merge-RCU-bh-into-RCU-preempt.patch b/debian/patches-rt/0158-rcu-Merge-RCU-bh-into-RCU-preempt.patch new file mode 100644 index 000000000..1c3897d25 --- /dev/null +++ b/debian/patches-rt/0158-rcu-Merge-RCU-bh-into-RCU-preempt.patch @@ -0,0 +1,351 @@ +From d21751c3efb035a08326d8a28789b91cb769ea70 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Wed, 5 Oct 2011 11:59:38 -0700 +Subject: [PATCH 158/347] rcu: Merge RCU-bh into RCU-preempt +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz + +The Linux kernel has long RCU-bh read-side critical sections that +intolerably increase scheduling latency under mainline's RCU-bh rules, +which include RCU-bh read-side critical sections being non-preemptible. +This patch therefore arranges for RCU-bh to be implemented in terms of +RCU-preempt for CONFIG_PREEMPT_RT_FULL=y. + +This has the downside of defeating the purpose of RCU-bh, namely, +handling the case where the system is subjected to a network-based +denial-of-service attack that keeps at least one CPU doing full-time +softirq processing. This issue will be fixed by a later commit. + +The current commit will need some work to make it appropriate for +mainline use, for example, it needs to be extended to cover Tiny RCU. + +[ paulmck: Added a useful changelog ] + +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> +Link: http://lkml.kernel.org/r/20111005185938.GA20403@linux.vnet.ibm.com +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +--- + include/linux/rcupdate.h | 19 +++++++++++++++++++ + include/linux/rcutree.h | 8 ++++++++ + kernel/rcu/rcu.h | 11 +++++++++-- + kernel/rcu/rcutorture.c | 7 +++++++ + kernel/rcu/tree.c | 26 ++++++++++++++++++++++++++ + kernel/rcu/tree.h | 2 ++ + kernel/rcu/update.c | 2 ++ + 7 files changed, 73 insertions(+), 2 deletions(-) + +diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h +index e6733d7911e9..08d64e5713fc 100644 +--- a/include/linux/rcupdate.h ++++ b/include/linux/rcupdate.h +@@ -56,7 +56,11 @@ void call_rcu(struct rcu_head *head, rcu_callback_t func); + #define call_rcu call_rcu_sched + #endif /* #else #ifdef CONFIG_PREEMPT_RCU */ + ++#ifdef CONFIG_PREEMPT_RT_FULL ++#define call_rcu_bh call_rcu ++#else + void call_rcu_bh(struct rcu_head *head, rcu_callback_t func); ++#endif + void call_rcu_sched(struct rcu_head *head, rcu_callback_t func); + void synchronize_sched(void); + void rcu_barrier_tasks(void); +@@ -261,7 +265,14 @@ extern struct lockdep_map rcu_sched_lock_map; + extern struct lockdep_map rcu_callback_map; + int debug_lockdep_rcu_enabled(void); + int rcu_read_lock_held(void); ++#ifdef CONFIG_PREEMPT_RT_FULL ++static inline int rcu_read_lock_bh_held(void) ++{ ++ return rcu_read_lock_held(); ++} ++#else + int rcu_read_lock_bh_held(void); ++#endif + int rcu_read_lock_sched_held(void); + + #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ +@@ -661,10 +672,14 @@ static inline void rcu_read_unlock(void) + static inline void rcu_read_lock_bh(void) + { + local_bh_disable(); ++#ifdef CONFIG_PREEMPT_RT_FULL ++ rcu_read_lock(); ++#else + __acquire(RCU_BH); + rcu_lock_acquire(&rcu_bh_lock_map); + RCU_LOCKDEP_WARN(!rcu_is_watching(), + "rcu_read_lock_bh() used illegally while idle"); ++#endif + } + + /* +@@ -674,10 +689,14 @@ static inline void rcu_read_lock_bh(void) + */ + static inline void rcu_read_unlock_bh(void) + { ++#ifdef CONFIG_PREEMPT_RT_FULL ++ rcu_read_unlock(); ++#else + RCU_LOCKDEP_WARN(!rcu_is_watching(), + "rcu_read_unlock_bh() used illegally while idle"); + rcu_lock_release(&rcu_bh_lock_map); + __release(RCU_BH); ++#endif + local_bh_enable(); + } + +diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h +index 914655848ef6..462ce061bac7 100644 +--- a/include/linux/rcutree.h ++++ b/include/linux/rcutree.h +@@ -44,7 +44,11 @@ static inline void rcu_virt_note_context_switch(int cpu) + rcu_note_context_switch(false); + } + ++#ifdef CONFIG_PREEMPT_RT_FULL ++# define synchronize_rcu_bh synchronize_rcu ++#else + void synchronize_rcu_bh(void); ++#endif + void synchronize_sched_expedited(void); + void synchronize_rcu_expedited(void); + +@@ -72,7 +76,11 @@ static inline void synchronize_rcu_bh_expedited(void) + } + + void rcu_barrier(void); ++#ifdef CONFIG_PREEMPT_RT_FULL ++# define rcu_barrier_bh rcu_barrier ++#else + void rcu_barrier_bh(void); ++#endif + void rcu_barrier_sched(void); + bool rcu_eqs_special_set(int cpu); + unsigned long get_state_synchronize_rcu(void); +diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h +index 4d04683c31b2..808cce9a5d43 100644 +--- a/kernel/rcu/rcu.h ++++ b/kernel/rcu/rcu.h +@@ -528,7 +528,6 @@ static inline void show_rcu_gp_kthreads(void) { } + static inline int rcu_get_gp_kthreads_prio(void) { return 0; } + #else /* #ifdef CONFIG_TINY_RCU */ + unsigned long rcu_get_gp_seq(void); +-unsigned long rcu_bh_get_gp_seq(void); + unsigned long rcu_sched_get_gp_seq(void); + unsigned long rcu_exp_batches_completed(void); + unsigned long rcu_exp_batches_completed_sched(void); +@@ -536,10 +535,18 @@ unsigned long srcu_batches_completed(struct srcu_struct *sp); + void show_rcu_gp_kthreads(void); + int rcu_get_gp_kthreads_prio(void); + void rcu_force_quiescent_state(void); +-void rcu_bh_force_quiescent_state(void); + void rcu_sched_force_quiescent_state(void); + extern struct workqueue_struct *rcu_gp_wq; + extern struct workqueue_struct *rcu_par_gp_wq; ++ ++#ifdef CONFIG_PREEMPT_RT_FULL ++#define rcu_bh_get_gp_seq rcu_get_gp_seq ++#define rcu_bh_force_quiescent_state rcu_force_quiescent_state ++#else ++unsigned long rcu_bh_get_gp_seq(void); ++void rcu_bh_force_quiescent_state(void); ++#endif ++ + #endif /* #else #ifdef CONFIG_TINY_RCU */ + + #ifdef CONFIG_RCU_NOCB_CPU +diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c +index 0b7af7e2bcbb..e95d121efc80 100644 +--- a/kernel/rcu/rcutorture.c ++++ b/kernel/rcu/rcutorture.c +@@ -434,6 +434,7 @@ static struct rcu_torture_ops rcu_ops = { + .name = "rcu" + }; + ++#ifndef CONFIG_PREEMPT_RT_FULL + /* + * Definitions for rcu_bh torture testing. + */ +@@ -475,6 +476,12 @@ static struct rcu_torture_ops rcu_bh_ops = { + .name = "rcu_bh" + }; + ++#else ++static struct rcu_torture_ops rcu_bh_ops = { ++ .ttype = INVALID_RCU_FLAVOR, ++}; ++#endif ++ + /* + * Don't even think about trying any of these in real life!!! + * The names includes "busted", and they really means it! +diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c +index f7e89c989df7..1456a3d97971 100644 +--- a/kernel/rcu/tree.c ++++ b/kernel/rcu/tree.c +@@ -244,6 +244,7 @@ void rcu_sched_qs(void) + this_cpu_ptr(&rcu_sched_data), true); + } + ++#ifndef CONFIG_PREEMPT_RT_FULL + void rcu_bh_qs(void) + { + RCU_LOCKDEP_WARN(preemptible(), "rcu_bh_qs() invoked with preemption enabled!!!"); +@@ -254,6 +255,11 @@ void rcu_bh_qs(void) + __this_cpu_write(rcu_bh_data.cpu_no_qs.b.norm, false); + } + } ++#else ++void rcu_bh_qs(void) ++{ ++} ++#endif + + /* + * Steal a bit from the bottom of ->dynticks for idle entry/exit +@@ -568,6 +574,7 @@ unsigned long rcu_sched_get_gp_seq(void) + } + EXPORT_SYMBOL_GPL(rcu_sched_get_gp_seq); + ++#ifndef CONFIG_PREEMPT_RT_FULL + /* + * Return the number of RCU-bh GPs completed thus far for debug & stats. + */ +@@ -576,6 +583,7 @@ unsigned long rcu_bh_get_gp_seq(void) + return READ_ONCE(rcu_bh_state.gp_seq); + } + EXPORT_SYMBOL_GPL(rcu_bh_get_gp_seq); ++#endif + + /* + * Return the number of RCU expedited batches completed thus far for +@@ -599,6 +607,7 @@ unsigned long rcu_exp_batches_completed_sched(void) + } + EXPORT_SYMBOL_GPL(rcu_exp_batches_completed_sched); + ++#ifndef CONFIG_PREEMPT_RT_FULL + /* + * Force a quiescent state. + */ +@@ -617,6 +626,13 @@ void rcu_bh_force_quiescent_state(void) + } + EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); + ++#else ++void rcu_force_quiescent_state(void) ++{ ++} ++EXPORT_SYMBOL_GPL(rcu_force_quiescent_state); ++#endif ++ + /* + * Force a quiescent state for RCU-sched. + */ +@@ -674,9 +690,11 @@ void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags, + case RCU_FLAVOR: + rsp = rcu_state_p; + break; ++#ifndef CONFIG_PREEMPT_RT_FULL + case RCU_BH_FLAVOR: + rsp = &rcu_bh_state; + break; ++#endif + case RCU_SCHED_FLAVOR: + rsp = &rcu_sched_state; + break; +@@ -3057,6 +3075,7 @@ void call_rcu_sched(struct rcu_head *head, rcu_callback_t func) + } + EXPORT_SYMBOL_GPL(call_rcu_sched); + ++#ifndef CONFIG_PREEMPT_RT_FULL + /** + * call_rcu_bh() - Queue an RCU for invocation after a quicker grace period. + * @head: structure to be used for queueing the RCU updates. +@@ -3084,6 +3103,7 @@ void call_rcu_bh(struct rcu_head *head, rcu_callback_t func) + __call_rcu(head, func, &rcu_bh_state, -1, 0); + } + EXPORT_SYMBOL_GPL(call_rcu_bh); ++#endif + + /* + * Queue an RCU callback for lazy invocation after a grace period. +@@ -3169,6 +3189,7 @@ void synchronize_sched(void) + } + EXPORT_SYMBOL_GPL(synchronize_sched); + ++#ifndef CONFIG_PREEMPT_RT_FULL + /** + * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. + * +@@ -3195,6 +3216,7 @@ void synchronize_rcu_bh(void) + wait_rcu_gp(call_rcu_bh); + } + EXPORT_SYMBOL_GPL(synchronize_rcu_bh); ++#endif + + /** + * get_state_synchronize_rcu - Snapshot current RCU state +@@ -3502,6 +3524,7 @@ static void _rcu_barrier(struct rcu_state *rsp) + mutex_unlock(&rsp->barrier_mutex); + } + ++#ifndef CONFIG_PREEMPT_RT_FULL + /** + * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. + */ +@@ -3510,6 +3533,7 @@ void rcu_barrier_bh(void) + _rcu_barrier(&rcu_bh_state); + } + EXPORT_SYMBOL_GPL(rcu_barrier_bh); ++#endif + + /** + * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. +@@ -4157,7 +4181,9 @@ void __init rcu_init(void) + + rcu_bootup_announce(); + rcu_init_geometry(); ++#ifndef CONFIG_PREEMPT_RT_FULL + rcu_init_one(&rcu_bh_state); ++#endif + rcu_init_one(&rcu_sched_state); + if (dump_tree) + rcu_dump_rcu_node_tree(&rcu_sched_state); +diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h +index 4e74df768c57..fbbff7c21148 100644 +--- a/kernel/rcu/tree.h ++++ b/kernel/rcu/tree.h +@@ -413,7 +413,9 @@ extern struct list_head rcu_struct_flavors; + */ + extern struct rcu_state rcu_sched_state; + ++#ifndef CONFIG_PREEMPT_RT_FULL + extern struct rcu_state rcu_bh_state; ++#endif + + #ifdef CONFIG_PREEMPT_RCU + extern struct rcu_state rcu_preempt_state; +diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c +index 81688a133552..6ffafb1b1584 100644 +--- a/kernel/rcu/update.c ++++ b/kernel/rcu/update.c +@@ -288,6 +288,7 @@ int rcu_read_lock_held(void) + } + EXPORT_SYMBOL_GPL(rcu_read_lock_held); + ++#ifndef CONFIG_PREEMPT_RT_FULL + /** + * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section? + * +@@ -314,6 +315,7 @@ int rcu_read_lock_bh_held(void) + return in_softirq() || irqs_disabled(); + } + EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); ++#endif + + #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ + +-- +2.36.1 + |