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authorIngo Molnar <mingo@kernel.org>2017-10-24 10:49:44 +0200
committerIngo Molnar <mingo@kernel.org>2017-10-24 10:49:44 +0200
commit72bc286b81d21404cdfecddf76b64c7163aac764 (patch)
tree3fb993e0171e13d51e1153d111f2b9acfe5fe68e /kernel
parentbb176f67090ca54869fc1262c913aa69d2ede070 (diff)
parentad4e25a3a1a5a95b334242d908e26f1249db83e0 (diff)
download96b-common-72bc286b81d21404cdfecddf76b64c7163aac764.tar.gz
Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull RCU updates from Paul E. McKenney: - Documentation updates - Miscellaneous fixes - RCU CPU stall-warning updates - Torture-test updates Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/irq_work.c9
-rw-r--r--kernel/rcu/rcu.h21
-rw-r--r--kernel/rcu/rcu_segcblist.c1
-rw-r--r--kernel/rcu/rcutorture.c24
-rw-r--r--kernel/rcu/tree.c159
-rw-r--r--kernel/rcu/tree.h5
-rw-r--r--kernel/rcu/tree_plugin.h14
-rw-r--r--kernel/rcu/update.c25
-rw-r--r--kernel/sched/core.c5
9 files changed, 196 insertions, 67 deletions
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index bcf107ce0854..9f20f6c72579 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -56,7 +56,6 @@ void __weak arch_irq_work_raise(void)
*/
}
-#ifdef CONFIG_SMP
/*
* Enqueue the irq_work @work on @cpu unless it's already pending
* somewhere.
@@ -68,6 +67,8 @@ bool irq_work_queue_on(struct irq_work *work, int cpu)
/* All work should have been flushed before going offline */
WARN_ON_ONCE(cpu_is_offline(cpu));
+#ifdef CONFIG_SMP
+
/* Arch remote IPI send/receive backend aren't NMI safe */
WARN_ON_ONCE(in_nmi());
@@ -78,10 +79,12 @@ bool irq_work_queue_on(struct irq_work *work, int cpu)
if (llist_add(&work->llnode, &per_cpu(raised_list, cpu)))
arch_send_call_function_single_ipi(cpu);
+#else /* #ifdef CONFIG_SMP */
+ irq_work_queue(work);
+#endif /* #else #ifdef CONFIG_SMP */
+
return true;
}
-EXPORT_SYMBOL_GPL(irq_work_queue_on);
-#endif
/* Enqueue the irq work @work on the current CPU */
bool irq_work_queue(struct irq_work *work)
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index e4b43fef89f5..59c471de342a 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -203,6 +203,21 @@ static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head)
extern int rcu_cpu_stall_suppress;
int rcu_jiffies_till_stall_check(void);
+#define rcu_ftrace_dump_stall_suppress() \
+do { \
+ if (!rcu_cpu_stall_suppress) \
+ rcu_cpu_stall_suppress = 3; \
+} while (0)
+
+#define rcu_ftrace_dump_stall_unsuppress() \
+do { \
+ if (rcu_cpu_stall_suppress == 3) \
+ rcu_cpu_stall_suppress = 0; \
+} while (0)
+
+#else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */
+#define rcu_ftrace_dump_stall_suppress()
+#define rcu_ftrace_dump_stall_unsuppress()
#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
/*
@@ -220,8 +235,12 @@ do { \
static atomic_t ___rfd_beenhere = ATOMIC_INIT(0); \
\
if (!atomic_read(&___rfd_beenhere) && \
- !atomic_xchg(&___rfd_beenhere, 1)) \
+ !atomic_xchg(&___rfd_beenhere, 1)) { \
+ tracing_off(); \
+ rcu_ftrace_dump_stall_suppress(); \
ftrace_dump(oops_dump_mode); \
+ rcu_ftrace_dump_stall_unsuppress(); \
+ } \
} while (0)
void rcu_early_boot_tests(void);
diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c
index 7649fcd2c4c7..88cba7c2956c 100644
--- a/kernel/rcu/rcu_segcblist.c
+++ b/kernel/rcu/rcu_segcblist.c
@@ -23,6 +23,7 @@
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
+#include <linux/rcupdate.h>
#include "rcu_segcblist.h"
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 45f2ffbc1e78..362eb2f78b3c 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -51,6 +51,7 @@
#include <asm/byteorder.h>
#include <linux/torture.h>
#include <linux/vmalloc.h>
+#include <linux/sched/debug.h>
#include "rcu.h"
@@ -89,6 +90,7 @@ torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
torture_param(int, stall_cpu_holdoff, 10,
"Time to wait before starting stall (s).");
+torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
torture_param(int, stat_interval, 60,
"Number of seconds between stats printk()s");
torture_param(int, stutter, 5, "Number of seconds to run/halt test");
@@ -1239,6 +1241,7 @@ rcu_torture_stats_print(void)
long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
static unsigned long rtcv_snap = ULONG_MAX;
+ static bool splatted;
struct task_struct *wtp;
for_each_possible_cpu(cpu) {
@@ -1324,6 +1327,10 @@ rcu_torture_stats_print(void)
gpnum, completed, flags,
wtp == NULL ? ~0UL : wtp->state,
wtp == NULL ? -1 : (int)task_cpu(wtp));
+ if (!splatted && wtp) {
+ sched_show_task(wtp);
+ splatted = true;
+ }
show_rcu_gp_kthreads();
rcu_ftrace_dump(DUMP_ALL);
}
@@ -1357,7 +1364,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
"fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
"test_boost=%d/%d test_boost_interval=%d "
"test_boost_duration=%d shutdown_secs=%d "
- "stall_cpu=%d stall_cpu_holdoff=%d "
+ "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
"n_barrier_cbs=%d "
"onoff_interval=%d onoff_holdoff=%d\n",
torture_type, tag, nrealreaders, nfakewriters,
@@ -1365,7 +1372,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
test_boost, cur_ops->can_boost,
test_boost_interval, test_boost_duration, shutdown_secs,
- stall_cpu, stall_cpu_holdoff,
+ stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
n_barrier_cbs,
onoff_interval, onoff_holdoff);
}
@@ -1430,12 +1437,19 @@ static int rcu_torture_stall(void *args)
if (!kthread_should_stop()) {
stop_at = get_seconds() + stall_cpu;
/* RCU CPU stall is expected behavior in following code. */
- pr_alert("rcu_torture_stall start.\n");
rcu_read_lock();
- preempt_disable();
+ if (stall_cpu_irqsoff)
+ local_irq_disable();
+ else
+ preempt_disable();
+ pr_alert("rcu_torture_stall start on CPU %d.\n",
+ smp_processor_id());
while (ULONG_CMP_LT(get_seconds(), stop_at))
continue; /* Induce RCU CPU stall warning. */
- preempt_enable();
+ if (stall_cpu_irqsoff)
+ local_irq_enable();
+ else
+ preempt_enable();
rcu_read_unlock();
pr_alert("rcu_torture_stall end.\n");
}
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 3e3650e94ae6..e4fe06d42385 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -534,8 +534,8 @@ module_param(rcu_kick_kthreads, bool, 0644);
* How long the grace period must be before we start recruiting
* quiescent-state help from rcu_note_context_switch().
*/
-static ulong jiffies_till_sched_qs = HZ / 20;
-module_param(jiffies_till_sched_qs, ulong, 0644);
+static ulong jiffies_till_sched_qs = HZ / 10;
+module_param(jiffies_till_sched_qs, ulong, 0444);
static bool rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp,
struct rcu_data *rdp);
@@ -837,6 +837,9 @@ static void rcu_eqs_enter(bool user)
* We crowbar the ->dynticks_nesting field to zero to allow for
* the possibility of usermode upcalls having messed up our count
* of interrupt nesting level during the prior busy period.
+ *
+ * If you add or remove a call to rcu_idle_enter(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_idle_enter(void)
{
@@ -852,6 +855,9 @@ void rcu_idle_enter(void)
* is permitted between this call and rcu_user_exit(). This way the
* CPU doesn't need to maintain the tick for RCU maintenance purposes
* when the CPU runs in userspace.
+ *
+ * If you add or remove a call to rcu_user_enter(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_user_enter(void)
{
@@ -875,6 +881,9 @@ void rcu_user_enter(void)
* Use things like work queues to work around this limitation.
*
* You have been warned.
+ *
+ * If you add or remove a call to rcu_irq_exit(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_exit(void)
{
@@ -899,6 +908,9 @@ void rcu_irq_exit(void)
/*
* Wrapper for rcu_irq_exit() where interrupts are enabled.
+ *
+ * If you add or remove a call to rcu_irq_exit_irqson(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_exit_irqson(void)
{
@@ -971,6 +983,9 @@ static void rcu_eqs_exit(bool user)
* allow for the possibility of usermode upcalls messing up our count
* of interrupt nesting level during the busy period that is just
* now starting.
+ *
+ * If you add or remove a call to rcu_idle_exit(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_idle_exit(void)
{
@@ -987,6 +1002,9 @@ void rcu_idle_exit(void)
*
* Exit RCU idle mode while entering the kernel because it can
* run a RCU read side critical section anytime.
+ *
+ * If you add or remove a call to rcu_user_exit(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_user_exit(void)
{
@@ -1012,6 +1030,9 @@ void rcu_user_exit(void)
* Use things like work queues to work around this limitation.
*
* You have been warned.
+ *
+ * If you add or remove a call to rcu_irq_enter(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_enter(void)
{
@@ -1037,6 +1058,9 @@ void rcu_irq_enter(void)
/*
* Wrapper for rcu_irq_enter() where interrupts are enabled.
+ *
+ * If you add or remove a call to rcu_irq_enter_irqson(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_enter_irqson(void)
{
@@ -1055,6 +1079,9 @@ void rcu_irq_enter_irqson(void)
* that the CPU is active. This implementation permits nested NMIs, as
* long as the nesting level does not overflow an int. (You will probably
* run out of stack space first.)
+ *
+ * If you add or remove a call to rcu_nmi_enter(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_nmi_enter(void)
{
@@ -1087,6 +1114,9 @@ void rcu_nmi_enter(void)
* RCU-idle period, update rdtp->dynticks and rdtp->dynticks_nmi_nesting
* to let the RCU grace-period handling know that the CPU is back to
* being RCU-idle.
+ *
+ * If you add or remove a call to rcu_nmi_exit(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_nmi_exit(void)
{
@@ -1207,6 +1237,22 @@ static int rcu_is_cpu_rrupt_from_idle(void)
}
/*
+ * We are reporting a quiescent state on behalf of some other CPU, so
+ * it is our responsibility to check for and handle potential overflow
+ * of the rcu_node ->gpnum counter with respect to the rcu_data counters.
+ * After all, the CPU might be in deep idle state, and thus executing no
+ * code whatsoever.
+ */
+static void rcu_gpnum_ovf(struct rcu_node *rnp, struct rcu_data *rdp)
+{
+ lockdep_assert_held(&rnp->lock);
+ if (ULONG_CMP_LT(READ_ONCE(rdp->gpnum) + ULONG_MAX / 4, rnp->gpnum))
+ WRITE_ONCE(rdp->gpwrap, true);
+ if (ULONG_CMP_LT(rdp->rcu_iw_gpnum + ULONG_MAX / 4, rnp->gpnum))
+ rdp->rcu_iw_gpnum = rnp->gpnum + ULONG_MAX / 4;
+}
+
+/*
* Snapshot the specified CPU's dynticks counter so that we can later
* credit them with an implicit quiescent state. Return 1 if this CPU
* is in dynticks idle mode, which is an extended quiescent state.
@@ -1216,15 +1262,34 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp)
rdp->dynticks_snap = rcu_dynticks_snap(rdp->dynticks);
if (rcu_dynticks_in_eqs(rdp->dynticks_snap)) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
- if (ULONG_CMP_LT(READ_ONCE(rdp->gpnum) + ULONG_MAX / 4,
- rdp->mynode->gpnum))
- WRITE_ONCE(rdp->gpwrap, true);
+ rcu_gpnum_ovf(rdp->mynode, rdp);
return 1;
}
return 0;
}
/*
+ * Handler for the irq_work request posted when a grace period has
+ * gone on for too long, but not yet long enough for an RCU CPU
+ * stall warning. Set state appropriately, but just complain if
+ * there is unexpected state on entry.
+ */
+static void rcu_iw_handler(struct irq_work *iwp)
+{
+ struct rcu_data *rdp;
+ struct rcu_node *rnp;
+
+ rdp = container_of(iwp, struct rcu_data, rcu_iw);
+ rnp = rdp->mynode;
+ raw_spin_lock_rcu_node(rnp);
+ if (!WARN_ON_ONCE(!rdp->rcu_iw_pending)) {
+ rdp->rcu_iw_gpnum = rnp->gpnum;
+ rdp->rcu_iw_pending = false;
+ }
+ raw_spin_unlock_rcu_node(rnp);
+}
+
+/*
* Return true if the specified CPU has passed through a quiescent
* state by virtue of being in or having passed through an dynticks
* idle state since the last call to dyntick_save_progress_counter()
@@ -1235,8 +1300,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
unsigned long jtsq;
bool *rnhqp;
bool *ruqp;
- unsigned long rjtsc;
- struct rcu_node *rnp;
+ struct rcu_node *rnp = rdp->mynode;
/*
* If the CPU passed through or entered a dynticks idle phase with
@@ -1249,34 +1313,25 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
if (rcu_dynticks_in_eqs_since(rdp->dynticks, rdp->dynticks_snap)) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
rdp->dynticks_fqs++;
+ rcu_gpnum_ovf(rnp, rdp);
return 1;
}
- /* Compute and saturate jiffies_till_sched_qs. */
- jtsq = jiffies_till_sched_qs;
- rjtsc = rcu_jiffies_till_stall_check();
- if (jtsq > rjtsc / 2) {
- WRITE_ONCE(jiffies_till_sched_qs, rjtsc);
- jtsq = rjtsc / 2;
- } else if (jtsq < 1) {
- WRITE_ONCE(jiffies_till_sched_qs, 1);
- jtsq = 1;
- }
-
/*
* Has this CPU encountered a cond_resched_rcu_qs() since the
* beginning of the grace period? For this to be the case,
* the CPU has to have noticed the current grace period. This
* might not be the case for nohz_full CPUs looping in the kernel.
*/
- rnp = rdp->mynode;
+ jtsq = jiffies_till_sched_qs;
ruqp = per_cpu_ptr(&rcu_dynticks.rcu_urgent_qs, rdp->cpu);
if (time_after(jiffies, rdp->rsp->gp_start + jtsq) &&
READ_ONCE(rdp->rcu_qs_ctr_snap) != per_cpu(rcu_dynticks.rcu_qs_ctr, rdp->cpu) &&
READ_ONCE(rdp->gpnum) == rnp->gpnum && !rdp->gpwrap) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("rqc"));
+ rcu_gpnum_ovf(rnp, rdp);
return 1;
- } else {
+ } else if (time_after(jiffies, rdp->rsp->gp_start + jtsq)) {
/* Load rcu_qs_ctr before store to rcu_urgent_qs. */
smp_store_release(ruqp, true);
}
@@ -1285,6 +1340,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
if (!(rdp->grpmask & rcu_rnp_online_cpus(rnp))) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("ofl"));
rdp->offline_fqs++;
+ rcu_gpnum_ovf(rnp, rdp);
return 1;
}
@@ -1304,10 +1360,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
* updates are only once every few jiffies, the probability of
* lossage (and thus of slight grace-period extension) is
* quite low.
- *
- * Note that if the jiffies_till_sched_qs boot/sysfs parameter
- * is set too high, we override with half of the RCU CPU stall
- * warning delay.
*/
rnhqp = &per_cpu(rcu_dynticks.rcu_need_heavy_qs, rdp->cpu);
if (!READ_ONCE(*rnhqp) &&
@@ -1316,15 +1368,26 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
WRITE_ONCE(*rnhqp, true);
/* Store rcu_need_heavy_qs before rcu_urgent_qs. */
smp_store_release(ruqp, true);
- rdp->rsp->jiffies_resched += 5; /* Re-enable beating. */
+ rdp->rsp->jiffies_resched += jtsq; /* Re-enable beating. */
}
/*
- * If more than halfway to RCU CPU stall-warning time, do
- * a resched_cpu() to try to loosen things up a bit.
+ * If more than halfway to RCU CPU stall-warning time, do a
+ * resched_cpu() to try to loosen things up a bit. Also check to
+ * see if the CPU is getting hammered with interrupts, but only
+ * once per grace period, just to keep the IPIs down to a dull roar.
*/
- if (jiffies - rdp->rsp->gp_start > rcu_jiffies_till_stall_check() / 2)
+ if (jiffies - rdp->rsp->gp_start > rcu_jiffies_till_stall_check() / 2) {
resched_cpu(rdp->cpu);
+ if (IS_ENABLED(CONFIG_IRQ_WORK) &&
+ !rdp->rcu_iw_pending && rdp->rcu_iw_gpnum != rnp->gpnum &&
+ (rnp->ffmask & rdp->grpmask)) {
+ init_irq_work(&rdp->rcu_iw, rcu_iw_handler);
+ rdp->rcu_iw_pending = true;
+ rdp->rcu_iw_gpnum = rnp->gpnum;
+ irq_work_queue_on(&rdp->rcu_iw, rdp->cpu);
+ }
+ }
return 0;
}
@@ -1513,6 +1576,7 @@ static void print_cpu_stall(struct rcu_state *rsp)
{
int cpu;
unsigned long flags;
+ struct rcu_data *rdp = this_cpu_ptr(rsp->rda);
struct rcu_node *rnp = rcu_get_root(rsp);
long totqlen = 0;
@@ -1528,7 +1592,9 @@ static void print_cpu_stall(struct rcu_state *rsp)
*/
pr_err("INFO: %s self-detected stall on CPU", rsp->name);
print_cpu_stall_info_begin();
+ raw_spin_lock_irqsave_rcu_node(rdp->mynode, flags);
print_cpu_stall_info(rsp, smp_processor_id());
+ raw_spin_unlock_irqrestore_rcu_node(rdp->mynode, flags);
print_cpu_stall_info_end();
for_each_possible_cpu(cpu)
totqlen += rcu_segcblist_n_cbs(&per_cpu_ptr(rsp->rda,
@@ -1922,6 +1988,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
rdp->core_needs_qs = need_gp;
zero_cpu_stall_ticks(rdp);
WRITE_ONCE(rdp->gpwrap, false);
+ rcu_gpnum_ovf(rnp, rdp);
}
return ret;
}
@@ -3702,6 +3769,8 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->cpu_no_qs.b.norm = true;
rdp->rcu_qs_ctr_snap = per_cpu(rcu_dynticks.rcu_qs_ctr, cpu);
rdp->core_needs_qs = false;
+ rdp->rcu_iw_pending = false;
+ rdp->rcu_iw_gpnum = rnp->gpnum - 1;
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl"));
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
@@ -3739,10 +3808,24 @@ static void rcutree_affinity_setting(unsigned int cpu, int outgoing)
*/
int rcutree_online_cpu(unsigned int cpu)
{
- sync_sched_exp_online_cleanup(cpu);
- rcutree_affinity_setting(cpu, -1);
+ unsigned long flags;
+ struct rcu_data *rdp;
+ struct rcu_node *rnp;
+ struct rcu_state *rsp;
+
+ for_each_rcu_flavor(rsp) {
+ rdp = per_cpu_ptr(rsp->rda, cpu);
+ rnp = rdp->mynode;
+ raw_spin_lock_irqsave_rcu_node(rnp, flags);
+ rnp->ffmask |= rdp->grpmask;
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
+ }
if (IS_ENABLED(CONFIG_TREE_SRCU))
srcu_online_cpu(cpu);
+ if (rcu_scheduler_active == RCU_SCHEDULER_INACTIVE)
+ return 0; /* Too early in boot for scheduler work. */
+ sync_sched_exp_online_cleanup(cpu);
+ rcutree_affinity_setting(cpu, -1);
return 0;
}
@@ -3752,6 +3835,19 @@ int rcutree_online_cpu(unsigned int cpu)
*/
int rcutree_offline_cpu(unsigned int cpu)
{
+ unsigned long flags;
+ struct rcu_data *rdp;
+ struct rcu_node *rnp;
+ struct rcu_state *rsp;
+
+ for_each_rcu_flavor(rsp) {
+ rdp = per_cpu_ptr(rsp->rda, cpu);
+ rnp = rdp->mynode;
+ raw_spin_lock_irqsave_rcu_node(rnp, flags);
+ rnp->ffmask &= ~rdp->grpmask;
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
+ }
+
rcutree_affinity_setting(cpu, cpu);
if (IS_ENABLED(CONFIG_TREE_SRCU))
srcu_offline_cpu(cpu);
@@ -4200,8 +4296,7 @@ void __init rcu_init(void)
for_each_online_cpu(cpu) {
rcutree_prepare_cpu(cpu);
rcu_cpu_starting(cpu);
- if (IS_ENABLED(CONFIG_TREE_SRCU))
- srcu_online_cpu(cpu);
+ rcutree_online_cpu(cpu);
}
}
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 8e1f285f0a70..46a5d1991450 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -103,6 +103,7 @@ struct rcu_node {
/* Online CPUs for next expedited GP. */
/* Any CPU that has ever been online will */
/* have its bit set. */
+ unsigned long ffmask; /* Fully functional CPUs. */
unsigned long grpmask; /* Mask to apply to parent qsmask. */
/* Only one bit will be set in this mask. */
int grplo; /* lowest-numbered CPU or group here. */
@@ -285,6 +286,10 @@ struct rcu_data {
/* 8) RCU CPU stall data. */
unsigned int softirq_snap; /* Snapshot of softirq activity. */
+ /* ->rcu_iw* fields protected by leaf rcu_node ->lock. */
+ struct irq_work rcu_iw; /* Check for non-irq activity. */
+ bool rcu_iw_pending; /* Is ->rcu_iw pending? */
+ unsigned long rcu_iw_gpnum; /* ->gpnum associated with ->rcu_iw. */
int cpu;
struct rcu_state *rsp;
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index e012b9be777e..4c857e583802 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -54,6 +54,7 @@ DEFINE_PER_CPU(char, rcu_cpu_has_work);
* This probably needs to be excluded from -rt builds.
*/
#define rt_mutex_owner(a) ({ WARN_ON_ONCE(1); NULL; })
+#define rt_mutex_futex_unlock(x) WARN_ON_ONCE(1)
#endif /* #else #ifdef CONFIG_RCU_BOOST */
@@ -530,7 +531,7 @@ void rcu_read_unlock_special(struct task_struct *t)
/* Unboost if we were boosted. */
if (IS_ENABLED(CONFIG_RCU_BOOST) && drop_boost_mutex)
- rt_mutex_unlock(&rnp->boost_mtx);
+ rt_mutex_futex_unlock(&rnp->boost_mtx);
/*
* If this was the last task on the expedited lists,
@@ -911,8 +912,6 @@ void exit_rcu(void)
#ifdef CONFIG_RCU_BOOST
-#include "../locking/rtmutex_common.h"
-
static void rcu_wake_cond(struct task_struct *t, int status)
{
/*
@@ -1507,7 +1506,7 @@ static void rcu_prepare_for_idle(void)
rdtp->last_accelerate = jiffies;
for_each_rcu_flavor(rsp) {
rdp = this_cpu_ptr(rsp->rda);
- if (rcu_segcblist_pend_cbs(&rdp->cblist))
+ if (!rcu_segcblist_pend_cbs(&rdp->cblist))
continue;
rnp = rdp->mynode;
raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
@@ -1671,6 +1670,7 @@ static void print_cpu_stall_info_begin(void)
*/
static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
{
+ unsigned long delta;
char fast_no_hz[72];
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
struct rcu_dynticks *rdtp = rdp->dynticks;
@@ -1685,11 +1685,15 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
ticks_value = rsp->gpnum - rdp->gpnum;
}
print_cpu_stall_fast_no_hz(fast_no_hz, cpu);
- pr_err("\t%d-%c%c%c: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u fqs=%ld %s\n",
+ delta = rdp->mynode->gpnum - rdp->rcu_iw_gpnum;
+ pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u fqs=%ld %s\n",
cpu,
"O."[!!cpu_online(cpu)],
"o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)],
"N."[!!(rdp->grpmask & rdp->mynode->qsmaskinitnext)],
+ !IS_ENABLED(CONFIG_IRQ_WORK) ? '?' :
+ rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' :
+ "!."[!delta],
ticks_value, ticks_title,
rcu_dynticks_snap(rdtp) & 0xfff,
rdtp->dynticks_nesting, rdtp->dynticks_nmi_nesting,
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 5033b66d2753..27694561f769 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -494,6 +494,7 @@ EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
#endif
int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
+EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress);
static int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
module_param(rcu_cpu_stall_suppress, int, 0644);
@@ -575,7 +576,6 @@ DEFINE_STATIC_SRCU(tasks_rcu_exit_srcu);
static int rcu_task_stall_timeout __read_mostly = RCU_TASK_STALL_TIMEOUT;
module_param(rcu_task_stall_timeout, int, 0644);
-static void rcu_spawn_tasks_kthread(void);
static struct task_struct *rcu_tasks_kthread_ptr;
/**
@@ -600,7 +600,6 @@ void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func)
{
unsigned long flags;
bool needwake;
- bool havetask = READ_ONCE(rcu_tasks_kthread_ptr);
rhp->next = NULL;
rhp->func = func;
@@ -610,11 +609,8 @@ void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func)
rcu_tasks_cbs_tail = &rhp->next;
raw_spin_unlock_irqrestore(&rcu_tasks_cbs_lock, flags);
/* We can't create the thread unless interrupts are enabled. */
- if ((needwake && havetask) ||
- (!havetask && !irqs_disabled_flags(flags))) {
- rcu_spawn_tasks_kthread();
+ if (needwake && READ_ONCE(rcu_tasks_kthread_ptr))
wake_up(&rcu_tasks_cbs_wq);
- }
}
EXPORT_SYMBOL_GPL(call_rcu_tasks);
@@ -853,27 +849,18 @@ static int __noreturn rcu_tasks_kthread(void *arg)
}
}
-/* Spawn rcu_tasks_kthread() at first call to call_rcu_tasks(). */
-static void rcu_spawn_tasks_kthread(void)
+/* Spawn rcu_tasks_kthread() at core_initcall() time. */
+static int __init rcu_spawn_tasks_kthread(void)
{
- static DEFINE_MUTEX(rcu_tasks_kthread_mutex);
struct task_struct *t;
- if (READ_ONCE(rcu_tasks_kthread_ptr)) {
- smp_mb(); /* Ensure caller sees full kthread. */
- return;
- }
- mutex_lock(&rcu_tasks_kthread_mutex);
- if (rcu_tasks_kthread_ptr) {
- mutex_unlock(&rcu_tasks_kthread_mutex);
- return;
- }
t = kthread_run(rcu_tasks_kthread, NULL, "rcu_tasks_kthread");
BUG_ON(IS_ERR(t));
smp_mb(); /* Ensure others see full kthread. */
WRITE_ONCE(rcu_tasks_kthread_ptr, t);
- mutex_unlock(&rcu_tasks_kthread_mutex);
+ return 0;
}
+core_initcall(rcu_spawn_tasks_kthread);
/* Do the srcu_read_lock() for the above synchronize_srcu(). */
void exit_tasks_rcu_start(void)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d17c5da523a0..9446b2e5eac5 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -505,8 +505,7 @@ void resched_cpu(int cpu)
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
- if (!raw_spin_trylock_irqsave(&rq->lock, flags))
- return;
+ raw_spin_lock_irqsave(&rq->lock, flags);
resched_curr(rq);
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
@@ -4842,6 +4841,7 @@ int __sched _cond_resched(void)
preempt_schedule_common();
return 1;
}
+ rcu_all_qs();
return 0;
}
EXPORT_SYMBOL(_cond_resched);
@@ -5165,6 +5165,7 @@ void sched_show_task(struct task_struct *p)
show_stack(p, NULL);
put_task_stack(p);
}
+EXPORT_SYMBOL_GPL(sched_show_task);
static inline bool
state_filter_match(unsigned long state_filter, struct task_struct *p)