From dfcb27540213e8061ecffacd4bd8ed54a310a7b0 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 19 May 2021 02:09:28 +0200 Subject: rcu/nocb: Start moving nocb code to its own plugin file The kernel/rcu/tree_plugin.h file contains not only the plugins for preemptible RCU, but also many other features including rcu_nocbs callback offloading. This offloading has become large and complex, so it is time to put it in its own file. This commit starts that process. Suggested-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker [ paulmck: Rename to tree_nocb.h, add Frederic as author. ] Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/rcu/tree.c') diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 51f24ecd94b2..b6eb480402e0 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4784,4 +4784,5 @@ void __init rcu_init(void) #include "tree_stall.h" #include "tree_exp.h" +#include "tree_nocb.h" #include "tree_plugin.h" -- cgit v1.2.3 From cba712beebf32b27fea71241aa3cdd2ab0fc31a3 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 19 May 2021 02:09:29 +0200 Subject: rcu/nocb: Remove NOCB deferred wakeup from rcutree_dead_cpu() At CPU offline time, we must handle any pending wakeup for the nocb_gp kthread linked to the outgoing CPU. Now we are making sure of that twice: 1) From rcu_report_dead() when the outgoing CPU makes the very last local cleanups by itself before switching offline. 2) From rcutree_dead_cpu(). Here the offlining CPU has gone and is truly now offline. Another CPU takes care of post-portem cleaning up and check if the offline CPU had pending wakeup. Both ways are fine but we have to choose one or the other because we don't need to repeat that action. Simply benefit from cache locality and keep only the first solution. Signed-off-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'kernel/rcu/tree.c') diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index b6eb480402e0..0fda98a0d12e 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2471,9 +2471,6 @@ int rcutree_dead_cpu(unsigned int cpu) WRITE_ONCE(rcu_state.n_online_cpus, rcu_state.n_online_cpus - 1); /* Adjust any no-longer-needed kthreads. */ rcu_boost_kthread_setaffinity(rnp, -1); - /* Do any needed no-CB deferred wakeups from this CPU. */ - do_nocb_deferred_wakeup(per_cpu_ptr(&rcu_data, cpu)); - // Stop-machine done, so allow nohz_full to disable tick. tick_dep_clear(TICK_DEP_BIT_RCU); return 0; -- cgit v1.2.3 From a86baa69c2b7b85bab41692fa3ec188a5aae1d27 Mon Sep 17 00:00:00 2001 From: "Joel Fernandes (Google)" Date: Tue, 18 May 2021 19:17:16 -0700 Subject: rcu: Remove special bit at the bottom of the ->dynticks counter Commit b8c17e6664c4 ("rcu: Maintain special bits at bottom of ->dynticks counter") reserved a bit at the bottom of the ->dynticks counter to defer flushing of TLBs, but this facility never has been used. This commit therefore removes this capability along with the rcu_eqs_special_set() function used to trigger it. Link: https://lore.kernel.org/linux-doc/CALCETrWNPOOdTrFabTDd=H7+wc6xJ9rJceg6OL1S0rTV5pfSsA@mail.gmail.com/ Suggested-by: Andy Lutomirski Signed-off-by: "Joel Fernandes (Google)" [ paulmck: Forward-port to v5.13-rc1. ] Signed-off-by: Paul E. McKenney --- include/linux/rcutiny.h | 3 -- kernel/rcu/tree.c | 77 +++++++++---------------------------------------- 2 files changed, 14 insertions(+), 66 deletions(-) (limited to 'kernel/rcu/tree.c') diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 953e70fafe38..9be015305f9f 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -14,9 +14,6 @@ #include /* for HZ */ -/* Never flag non-existent other CPUs! */ -static inline bool rcu_eqs_special_set(int cpu) { return false; } - unsigned long get_state_synchronize_rcu(void); unsigned long start_poll_synchronize_rcu(void); bool poll_state_synchronize_rcu(unsigned long oldstate); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 51f24ecd94b2..42a0032dd99f 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -74,17 +74,10 @@ /* Data structures. */ -/* - * Steal a bit from the bottom of ->dynticks for idle entry/exit - * control. Initially this is for TLB flushing. - */ -#define RCU_DYNTICK_CTRL_MASK 0x1 -#define RCU_DYNTICK_CTRL_CTR (RCU_DYNTICK_CTRL_MASK + 1) - static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = { .dynticks_nesting = 1, .dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE, - .dynticks = ATOMIC_INIT(RCU_DYNTICK_CTRL_CTR), + .dynticks = ATOMIC_INIT(1), #ifdef CONFIG_RCU_NOCB_CPU .cblist.flags = SEGCBLIST_SOFTIRQ_ONLY, #endif @@ -266,7 +259,6 @@ void rcu_softirq_qs(void) */ static noinstr void rcu_dynticks_eqs_enter(void) { - struct rcu_data *rdp = this_cpu_ptr(&rcu_data); int seq; /* @@ -275,13 +267,9 @@ static noinstr void rcu_dynticks_eqs_enter(void) * next idle sojourn. */ rcu_dynticks_task_trace_enter(); // Before ->dynticks update! - seq = arch_atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks); + seq = arch_atomic_inc_return(&this_cpu_ptr(&rcu_data)->dynticks); // RCU is no longer watching. Better be in extended quiescent state! - WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && - (seq & RCU_DYNTICK_CTRL_CTR)); - /* Better not have special action (TLB flush) pending! */ - WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && - (seq & RCU_DYNTICK_CTRL_MASK)); + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & 0x1)); } /* @@ -291,7 +279,6 @@ static noinstr void rcu_dynticks_eqs_enter(void) */ static noinstr void rcu_dynticks_eqs_exit(void) { - struct rcu_data *rdp = this_cpu_ptr(&rcu_data); int seq; /* @@ -299,15 +286,10 @@ static noinstr void rcu_dynticks_eqs_exit(void) * and we also must force ordering with the next RCU read-side * critical section. */ - seq = arch_atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks); + seq = arch_atomic_inc_return(&this_cpu_ptr(&rcu_data)->dynticks); // RCU is now watching. Better not be in an extended quiescent state! rcu_dynticks_task_trace_exit(); // After ->dynticks update! - WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && - !(seq & RCU_DYNTICK_CTRL_CTR)); - if (seq & RCU_DYNTICK_CTRL_MASK) { - arch_atomic_andnot(RCU_DYNTICK_CTRL_MASK, &rdp->dynticks); - smp_mb__after_atomic(); /* _exit after clearing mask. */ - } + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & 0x1)); } /* @@ -324,9 +306,9 @@ static void rcu_dynticks_eqs_online(void) { struct rcu_data *rdp = this_cpu_ptr(&rcu_data); - if (atomic_read(&rdp->dynticks) & RCU_DYNTICK_CTRL_CTR) + if (atomic_read(&rdp->dynticks) & 0x1) return; - atomic_add(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks); + atomic_inc(&rdp->dynticks); } /* @@ -336,9 +318,7 @@ static void rcu_dynticks_eqs_online(void) */ static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void) { - struct rcu_data *rdp = this_cpu_ptr(&rcu_data); - - return !(arch_atomic_read(&rdp->dynticks) & RCU_DYNTICK_CTRL_CTR); + return !(arch_atomic_read(&this_cpu_ptr(&rcu_data)->dynticks) & 0x1); } /* @@ -347,9 +327,7 @@ static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void) */ static int rcu_dynticks_snap(struct rcu_data *rdp) { - int snap = atomic_add_return(0, &rdp->dynticks); - - return snap & ~RCU_DYNTICK_CTRL_MASK; + return atomic_add_return(0, &rdp->dynticks); } /* @@ -358,7 +336,7 @@ static int rcu_dynticks_snap(struct rcu_data *rdp) */ static bool rcu_dynticks_in_eqs(int snap) { - return !(snap & RCU_DYNTICK_CTRL_CTR); + return !(snap & 0x1); } /* Return true if the specified CPU is currently idle from an RCU viewpoint. */ @@ -389,8 +367,7 @@ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp) int snap; // If not quiescent, force back to earlier extended quiescent state. - snap = atomic_read(&rdp->dynticks) & ~(RCU_DYNTICK_CTRL_MASK | - RCU_DYNTICK_CTRL_CTR); + snap = atomic_read(&rdp->dynticks) & ~0x1; smp_rmb(); // Order ->dynticks and *vp reads. if (READ_ONCE(*vp)) @@ -398,32 +375,7 @@ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp) smp_rmb(); // Order *vp read and ->dynticks re-read. // If still in the same extended quiescent state, we are good! - return snap == (atomic_read(&rdp->dynticks) & ~RCU_DYNTICK_CTRL_MASK); -} - -/* - * Set the special (bottom) bit of the specified CPU so that it - * will take special action (such as flushing its TLB) on the - * next exit from an extended quiescent state. Returns true if - * the bit was successfully set, or false if the CPU was not in - * an extended quiescent state. - */ -bool rcu_eqs_special_set(int cpu) -{ - int old; - int new; - int new_old; - struct rcu_data *rdp = &per_cpu(rcu_data, cpu); - - new_old = atomic_read(&rdp->dynticks); - do { - old = new_old; - if (old & RCU_DYNTICK_CTRL_CTR) - return false; - new = old | RCU_DYNTICK_CTRL_MASK; - new_old = atomic_cmpxchg(&rdp->dynticks, old, new); - } while (new_old != old); - return true; + return snap == atomic_read(&rdp->dynticks); } /* @@ -442,10 +394,9 @@ notrace void rcu_momentary_dyntick_idle(void) int special; raw_cpu_write(rcu_data.rcu_need_heavy_qs, false); - special = atomic_add_return(2 * RCU_DYNTICK_CTRL_CTR, - &this_cpu_ptr(&rcu_data)->dynticks); + special = atomic_add_return(2, &this_cpu_ptr(&rcu_data)->dynticks); /* It is illegal to call this from idle state. */ - WARN_ON_ONCE(!(special & RCU_DYNTICK_CTRL_CTR)); + WARN_ON_ONCE(!(special & 0x1)); rcu_preempt_deferred_qs(current); } EXPORT_SYMBOL_GPL(rcu_momentary_dyntick_idle); -- cgit v1.2.3 From 2be57f732889277b07ccddd205ef0616c8c1941f Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 19 May 2021 17:25:42 -0700 Subject: rcu: Weaken ->dynticks accesses and updates Accesses to the rcu_data structure's ->dynticks field have always been fully ordered because it was not possible to prove that weaker ordering was safe. However, with the removal of the rcu_eqs_special_set() function and the advent of the Linux-kernel memory model, it is now easy to show that two of the four original full memory barriers can be weakened to acquire and release operations. The remaining pair must remain full memory barriers. This change makes the memory ordering requirements more evident, and it might well also speed up the to-idle and from-idle fastpaths on some architectures. The following litmus test, adapted from one supplied off-list by Frederic Weisbecker, models the RCU grace-period kthread detecting an idle CPU that is concurrently transitioning to non-idle: C dynticks-from-idle { DYNTICKS=0; (* Initially idle. *) } P0(int *X, int *DYNTICKS) { int dynticks; int x; // Idle. dynticks = READ_ONCE(*DYNTICKS); smp_store_release(DYNTICKS, dynticks + 1); smp_mb(); // Now non-idle x = READ_ONCE(*X); } P1(int *X, int *DYNTICKS) { int dynticks; WRITE_ONCE(*X, 1); smp_mb(); dynticks = smp_load_acquire(DYNTICKS); } exists (1:dynticks=0 /\ 0:x=1) Running "herd7 -conf linux-kernel.cfg dynticks-from-idle.litmus" verifies this transition, namely, showing that if the RCU grace-period kthread (P1) sees another CPU as idle (P0), then any memory access prior to the start of the grace period (P1's write to X) will be seen by any RCU read-side critical section following the to-non-idle transition (P0's read from X). This is a straightforward use of full memory barriers to force ordering in a store-buffering (SB) litmus test. The following litmus test, also adapted from the one supplied off-list by Frederic Weisbecker, models the RCU grace-period kthread detecting a non-idle CPU that is concurrently transitioning to idle: C dynticks-into-idle { DYNTICKS=1; (* Initially non-idle. *) } P0(int *X, int *DYNTICKS) { int dynticks; // Non-idle. WRITE_ONCE(*X, 1); dynticks = READ_ONCE(*DYNTICKS); smp_store_release(DYNTICKS, dynticks + 1); smp_mb(); // Now idle. } P1(int *X, int *DYNTICKS) { int x; int dynticks; smp_mb(); dynticks = smp_load_acquire(DYNTICKS); x = READ_ONCE(*X); } exists (1:dynticks=2 /\ 1:x=0) Running "herd7 -conf linux-kernel.cfg dynticks-into-idle.litmus" verifies this transition, namely, showing that if the RCU grace-period kthread (P1) sees another CPU as newly idle (P0), then any pre-idle memory access (P0's write to X) will be seen by any code following the grace period (P1's read from X). This is a simple release-acquire pair forcing ordering in a message-passing (MP) litmus test. Of course, if the grace-period kthread detects the CPU as non-idle, it will refrain from reporting a quiescent state on behalf of that CPU, so there are no ordering requirements from the grace-period kthread in that case. However, other subsystems call rcu_is_idle_cpu() to check for CPUs being non-idle from an RCU perspective. That case is also verified by the above litmus tests with the proviso that the sense of the low-order bit of the DYNTICKS counter be inverted. Unfortunately, on x86 smp_mb() is as expensive as a cache-local atomic increment. This commit therefore weakens only the read from ->dynticks. However, the updates are abstracted into a rcu_dynticks_inc() function to ease any future changes that might be needed. [ paulmck: Apply Linus Torvalds feedback. ] Link: https://lore.kernel.org/lkml/20210721202127.2129660-4-paulmck@kernel.org/ Suggested-by: Linus Torvalds Acked-by: Mathieu Desnoyers Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-) (limited to 'kernel/rcu/tree.c') diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 42a0032dd99f..381ebd3ae26c 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -251,6 +251,15 @@ void rcu_softirq_qs(void) rcu_tasks_qs(current, false); } +/* + * Increment the current CPU's rcu_data structure's ->dynticks field + * with ordering. Return the new value. + */ +static noinline noinstr unsigned long rcu_dynticks_inc(int incby) +{ + return arch_atomic_add_return(incby, this_cpu_ptr(&rcu_data.dynticks)); +} + /* * Record entry into an extended quiescent state. This is only to be * called when not already in an extended quiescent state, that is, @@ -267,7 +276,7 @@ static noinstr void rcu_dynticks_eqs_enter(void) * next idle sojourn. */ rcu_dynticks_task_trace_enter(); // Before ->dynticks update! - seq = arch_atomic_inc_return(&this_cpu_ptr(&rcu_data)->dynticks); + seq = rcu_dynticks_inc(1); // RCU is no longer watching. Better be in extended quiescent state! WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & 0x1)); } @@ -286,7 +295,7 @@ static noinstr void rcu_dynticks_eqs_exit(void) * and we also must force ordering with the next RCU read-side * critical section. */ - seq = arch_atomic_inc_return(&this_cpu_ptr(&rcu_data)->dynticks); + seq = rcu_dynticks_inc(1); // RCU is now watching. Better not be in an extended quiescent state! rcu_dynticks_task_trace_exit(); // After ->dynticks update! WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & 0x1)); @@ -308,7 +317,7 @@ static void rcu_dynticks_eqs_online(void) if (atomic_read(&rdp->dynticks) & 0x1) return; - atomic_inc(&rdp->dynticks); + rcu_dynticks_inc(1); } /* @@ -318,7 +327,7 @@ static void rcu_dynticks_eqs_online(void) */ static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void) { - return !(arch_atomic_read(&this_cpu_ptr(&rcu_data)->dynticks) & 0x1); + return !(atomic_read(this_cpu_ptr(&rcu_data.dynticks)) & 0x1); } /* @@ -327,7 +336,8 @@ static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void) */ static int rcu_dynticks_snap(struct rcu_data *rdp) { - return atomic_add_return(0, &rdp->dynticks); + smp_mb(); // Fundamental RCU ordering guarantee. + return atomic_read_acquire(&rdp->dynticks); } /* @@ -391,12 +401,12 @@ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp) */ notrace void rcu_momentary_dyntick_idle(void) { - int special; + int seq; raw_cpu_write(rcu_data.rcu_need_heavy_qs, false); - special = atomic_add_return(2, &this_cpu_ptr(&rcu_data)->dynticks); + seq = rcu_dynticks_inc(2); /* It is illegal to call this from idle state. */ - WARN_ON_ONCE(!(special & 0x1)); + WARN_ON_ONCE(!(seq & 0x1)); rcu_preempt_deferred_qs(current); } EXPORT_SYMBOL_GPL(rcu_momentary_dyntick_idle); -- cgit v1.2.3 From f74126dcbcbffe0d9fc3cb9bbf171b124a6791e5 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 7 Jun 2021 21:57:02 -0700 Subject: rcu: Make rcu_gp_init() and rcu_gp_fqs_loop noinline to conserve stack The kbuild test project found an oversized stack frame in rcu_gp_kthread() for some kernel configurations. This oversizing was due to a very large amount of inlining, which is unnecessary due to the fact that this code executes infrequently. This commit therefore marks rcu_gp_init() and rcu_gp_fqs_loop noinline_for_stack to conserve stack space. Reported-by: kernel test robot Tested-by: Rong Chen [ paulmck: noinline_for_stack per Nathan Chancellor. ] Reviewed-by: Nathan Chancellor Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/rcu/tree.c') diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 381ebd3ae26c..d791c4d32987 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1733,7 +1733,7 @@ static void rcu_strict_gp_boundary(void *unused) /* * Initialize a new grace period. Return false if no grace period required. */ -static bool rcu_gp_init(void) +static noinline_for_stack bool rcu_gp_init(void) { unsigned long firstseq; unsigned long flags; @@ -1927,7 +1927,7 @@ static void rcu_gp_fqs(bool first_time) /* * Loop doing repeated quiescent-state forcing until the grace period ends. */ -static void rcu_gp_fqs_loop(void) +static noinline_for_stack void rcu_gp_fqs_loop(void) { bool first_gp_fqs; int gf = 0; -- cgit v1.2.3 From eb880949ef41c98a203c4a033e06e05854d902ef Mon Sep 17 00:00:00 2001 From: Liu Song Date: Tue, 29 Jun 2021 21:55:51 +0800 Subject: rcu: Remove useless "ret" update in rcu_gp_fqs_loop() Within rcu_gp_fqs_loop(), the "ret" local variable is set to the return value from swait_event_idle_timeout_exclusive(), but "ret" is unconditionally overwritten later in the code. This commit therefore removes this useless assignment. Signed-off-by: Liu Song Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/rcu/tree.c') diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index d791c4d32987..2f000e8a315d 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1954,8 +1954,8 @@ static noinline_for_stack void rcu_gp_fqs_loop(void) trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("fqswait")); WRITE_ONCE(rcu_state.gp_state, RCU_GP_WAIT_FQS); - ret = swait_event_idle_timeout_exclusive( - rcu_state.gp_wq, rcu_gp_fqs_check_wake(&gf), j); + (void)swait_event_idle_timeout_exclusive(rcu_state.gp_wq, + rcu_gp_fqs_check_wake(&gf), j); rcu_gp_torture_wait(); WRITE_ONCE(rcu_state.gp_state, RCU_GP_DOING_FQS); /* Locking provides needed memory barriers. */ -- cgit v1.2.3 From 8211e922de2854130e3633f52cd4fc2d7817ceb0 Mon Sep 17 00:00:00 2001 From: Liu Song Date: Wed, 30 Jun 2021 22:08:02 +0800 Subject: rcu: Use per_cpu_ptr to get the pointer of per_cpu variable There are a few remaining locations in kernel/rcu that still use "&per_cpu()". This commit replaces them with "per_cpu_ptr(&)", and does not introduce any functional change. Reviewed-by: Uladzislau Rezki (Sony) Reviewed-by: Neeraj Upadhyay Reviewed-by: Joel Fernandes (Google) Signed-off-by: Liu Song Signed-off-by: Paul E. McKenney --- kernel/rcu/tasks.h | 2 +- kernel/rcu/tree.c | 2 +- kernel/rcu/tree_stall.h | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/rcu/tree.c') diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 8536c55df514..21f00194e69d 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -920,7 +920,7 @@ reset_ipi: // Allow future IPIs to be sent on CPU and for task. // Also order this IPI handler against any later manipulations of // the intended task. - smp_store_release(&per_cpu(trc_ipi_to_cpu, smp_processor_id()), false); // ^^^ + smp_store_release(per_cpu_ptr(&trc_ipi_to_cpu, smp_processor_id()), false); // ^^^ smp_store_release(&texp->trc_ipi_to_cpu, -1); // ^^^ } diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 2f000e8a315d..7403328cdf99 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1286,7 +1286,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) */ jtsq = READ_ONCE(jiffies_to_sched_qs); ruqp = per_cpu_ptr(&rcu_data.rcu_urgent_qs, rdp->cpu); - rnhqp = &per_cpu(rcu_data.rcu_need_heavy_qs, rdp->cpu); + rnhqp = per_cpu_ptr(&rcu_data.rcu_need_heavy_qs, rdp->cpu); if (!READ_ONCE(*rnhqp) && (time_after(jiffies, rcu_state.gp_start + jtsq * 2) || time_after(jiffies, rcu_state.jiffies_resched) || diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index a8d0fcf0826f..677ee3d8671b 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -351,7 +351,7 @@ static void rcu_dump_cpu_stacks(void) static void print_cpu_stall_fast_no_hz(char *cp, int cpu) { - struct rcu_data *rdp = &per_cpu(rcu_data, cpu); + struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); sprintf(cp, "last_accelerate: %04lx/%04lx dyntick_enabled: %d", rdp->last_accelerate & 0xffff, jiffies & 0xffff, -- cgit v1.2.3 From d3dd95a8853f1d588e38e9d9d7c8cc2da412cc36 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Tue, 3 Aug 2021 16:16:14 +0200 Subject: rcu: Replace deprecated CPU-hotplug functions The functions get_online_cpus() and put_online_cpus() have been deprecated during the CPU hotplug rework. They map directly to cpus_read_lock() and cpus_read_unlock(). Replace deprecated CPU-hotplug functions with the official version. The behavior remains unchanged. Cc: "Paul E. McKenney" Cc: Josh Triplett Cc: Steven Rostedt Cc: Mathieu Desnoyers Cc: Lai Jiangshan Cc: Joel Fernandes Cc: rcu@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/rcu/tree.c') diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 7403328cdf99..f53a3c1bf1d1 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4011,7 +4011,7 @@ void rcu_barrier(void) */ init_completion(&rcu_state.barrier_completion); atomic_set(&rcu_state.barrier_cpu_count, 2); - get_online_cpus(); + cpus_read_lock(); /* * Force each CPU with callbacks to register a new callback. @@ -4042,7 +4042,7 @@ void rcu_barrier(void) rcu_state.barrier_sequence); } } - put_online_cpus(); + cpus_read_unlock(); /* * Now that we have an rcu_barrier_callback() callback on each -- cgit v1.2.3