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rcu: Move FAST_NO_HZ stall-warning code to tree_stall.h

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This commit further consolidates the stall-warning code by moving
print_cpu_stall_info() and its helper functions along with
zero_cpu_stall_ticks() to kernel/rcu/tree_stall.h.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
This commit is contained in:
Paul E. McKenney 2019-01-11 21:05:17 -08:00
parent 40e69ac7d0
commit 59b73a2768
3 changed files with 80 additions and 81 deletions
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1
kernel/rcu/tree.h
View File

@ -416,7 +416,6 @@ static void rcu_prepare_for_idle(void);
static bool rcu_preempt_has_tasks(struct rcu_node *rnp);
static bool rcu_preempt_need_deferred_qs(struct task_struct *t);
static void rcu_preempt_deferred_qs(struct task_struct *t);
static void print_cpu_stall_info(int cpu);
static void zero_cpu_stall_ticks(struct rcu_data *rdp);
static bool rcu_nocb_cpu_needs_barrier(int cpu);
static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp);

80
kernel/rcu/tree_plugin.h
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@ -1528,86 +1528,6 @@ static void rcu_cleanup_after_idle(void)
#endif /* #else #if !defined(CONFIG_RCU_FAST_NO_HZ) */
#ifdef CONFIG_RCU_FAST_NO_HZ
static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
{
struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
sprintf(cp, "last_accelerate: %04lx/%04lx, Nonlazy posted: %c%c%c",
rdp->last_accelerate & 0xffff, jiffies & 0xffff,
".l"[rdp->all_lazy],
".L"[!rcu_segcblist_n_nonlazy_cbs(&rdp->cblist)],
".D"[!rdp->tick_nohz_enabled_snap]);
}
#else /* #ifdef CONFIG_RCU_FAST_NO_HZ */
static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
{
*cp = '\0';
}
#endif /* #else #ifdef CONFIG_RCU_FAST_NO_HZ */
/*
* Print out diagnostic information for the specified stalled CPU.
*
* If the specified CPU is aware of the current RCU grace period, then
* print the number of scheduling clock interrupts the CPU has taken
* during the time that it has been aware. Otherwise, print the number
* of RCU grace periods that this CPU is ignorant of, for example, "1"
* if the CPU was aware of the previous grace period.
*
* Also print out idle and (if CONFIG_RCU_FAST_NO_HZ) idle-entry info.
*/
static void print_cpu_stall_info(int cpu)
{
unsigned long delta;
char fast_no_hz[72];
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
char *ticks_title;
unsigned long ticks_value;
/*
* We could be printing a lot while holding a spinlock. Avoid
* triggering hard lockup.
*/
touch_nmi_watchdog();
ticks_value = rcu_seq_ctr(rcu_state.gp_seq - rdp->gp_seq);
if (ticks_value) {
ticks_title = "GPs behind";
} else {
ticks_title = "ticks this GP";
ticks_value = rdp->ticks_this_gp;
}
print_cpu_stall_fast_no_hz(fast_no_hz, cpu);
delta = rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq);
pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%ld/%#lx 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(rdp) & 0xfff,
rdp->dynticks_nesting, rdp->dynticks_nmi_nesting,
rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
READ_ONCE(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
fast_no_hz);
}
/* Zero ->ticks_this_gp and snapshot the number of RCU softirq handlers. */
static void zero_cpu_stall_ticks(struct rcu_data *rdp)
{
rdp->ticks_this_gp = 0;
rdp->softirq_snap = kstat_softirqs_cpu(RCU_SOFTIRQ, smp_processor_id());
WRITE_ONCE(rdp->last_fqs_resched, jiffies);
}
#ifdef CONFIG_RCU_NOCB_CPU
/*

80
kernel/rcu/tree_stall.h
View File

@ -223,6 +223,86 @@ static void panic_on_rcu_stall(void)
panic("RCU Stall\n");
}
#ifdef CONFIG_RCU_FAST_NO_HZ
static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
{
struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
sprintf(cp, "last_accelerate: %04lx/%04lx, Nonlazy posted: %c%c%c",
rdp->last_accelerate & 0xffff, jiffies & 0xffff,
".l"[rdp->all_lazy],
".L"[!rcu_segcblist_n_nonlazy_cbs(&rdp->cblist)],
".D"[!rdp->tick_nohz_enabled_snap]);
}
#else /* #ifdef CONFIG_RCU_FAST_NO_HZ */
static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
{
*cp = '\0';
}
#endif /* #else #ifdef CONFIG_RCU_FAST_NO_HZ */
/*
* Print out diagnostic information for the specified stalled CPU.
*
* If the specified CPU is aware of the current RCU grace period, then
* print the number of scheduling clock interrupts the CPU has taken
* during the time that it has been aware. Otherwise, print the number
* of RCU grace periods that this CPU is ignorant of, for example, "1"
* if the CPU was aware of the previous grace period.
*
* Also print out idle and (if CONFIG_RCU_FAST_NO_HZ) idle-entry info.
*/
static void print_cpu_stall_info(int cpu)
{
unsigned long delta;
char fast_no_hz[72];
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
char *ticks_title;
unsigned long ticks_value;
/*
* We could be printing a lot while holding a spinlock. Avoid
* triggering hard lockup.
*/
touch_nmi_watchdog();
ticks_value = rcu_seq_ctr(rcu_state.gp_seq - rdp->gp_seq);
if (ticks_value) {
ticks_title = "GPs behind";
} else {
ticks_title = "ticks this GP";
ticks_value = rdp->ticks_this_gp;
}
print_cpu_stall_fast_no_hz(fast_no_hz, cpu);
delta = rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq);
pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%ld/%#lx 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(rdp) & 0xfff,
rdp->dynticks_nesting, rdp->dynticks_nmi_nesting,
rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
READ_ONCE(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
fast_no_hz);
}
/* Zero ->ticks_this_gp and snapshot the number of RCU softirq handlers. */
static void zero_cpu_stall_ticks(struct rcu_data *rdp)
{
rdp->ticks_this_gp = 0;
rdp->softirq_snap = kstat_softirqs_cpu(RCU_SOFTIRQ, smp_processor_id());
WRITE_ONCE(rdp->last_fqs_resched, jiffies);
}
static void print_other_cpu_stall(unsigned long gp_seq)
{
int cpu;