#include <linux/sched/debug.h>
#include <linux/jump_label.h>
+#include <trace/events/ipi.h>
+
#include "smpboot.h"
#include "sched/smp.h"
#define CSD_TYPE(_csd) ((_csd)->node.u_flags & CSD_FLAG_TYPE_MASK)
-#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
-union cfd_seq_cnt {
- u64 val;
- struct {
- u64 src:16;
- u64 dst:16;
-#define CFD_SEQ_NOCPU 0xffff
- u64 type:4;
-#define CFD_SEQ_QUEUE 0
-#define CFD_SEQ_IPI 1
-#define CFD_SEQ_NOIPI 2
-#define CFD_SEQ_PING 3
-#define CFD_SEQ_PINGED 4
-#define CFD_SEQ_HANDLE 5
-#define CFD_SEQ_DEQUEUE 6
-#define CFD_SEQ_IDLE 7
-#define CFD_SEQ_GOTIPI 8
-#define CFD_SEQ_HDLEND 9
- u64 cnt:28;
- } u;
-};
-
-static char *seq_type[] = {
- [CFD_SEQ_QUEUE] = "queue",
- [CFD_SEQ_IPI] = "ipi",
- [CFD_SEQ_NOIPI] = "noipi",
- [CFD_SEQ_PING] = "ping",
- [CFD_SEQ_PINGED] = "pinged",
- [CFD_SEQ_HANDLE] = "handle",
- [CFD_SEQ_DEQUEUE] = "dequeue (src CPU 0 == empty)",
- [CFD_SEQ_IDLE] = "idle",
- [CFD_SEQ_GOTIPI] = "gotipi",
- [CFD_SEQ_HDLEND] = "hdlend (src CPU 0 == early)",
-};
-
-struct cfd_seq_local {
- u64 ping;
- u64 pinged;
- u64 handle;
- u64 dequeue;
- u64 idle;
- u64 gotipi;
- u64 hdlend;
-};
-#endif
-
-struct cfd_percpu {
- call_single_data_t csd;
-#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
- u64 seq_queue;
- u64 seq_ipi;
- u64 seq_noipi;
-#endif
-};
-
struct call_function_data {
- struct cfd_percpu __percpu *pcpu;
+ call_single_data_t __percpu *csd;
cpumask_var_t cpumask;
cpumask_var_t cpumask_ipi;
};
free_cpumask_var(cfd->cpumask);
return -ENOMEM;
}
- cfd->pcpu = alloc_percpu(struct cfd_percpu);
- if (!cfd->pcpu) {
+ cfd->csd = alloc_percpu(call_single_data_t);
+ if (!cfd->csd) {
free_cpumask_var(cfd->cpumask);
free_cpumask_var(cfd->cpumask_ipi);
return -ENOMEM;
free_cpumask_var(cfd->cpumask);
free_cpumask_var(cfd->cpumask_ipi);
- free_percpu(cfd->pcpu);
+ free_percpu(cfd->csd);
return 0;
}
smpcfd_prepare_cpu(smp_processor_id());
}
+static __always_inline void
+send_call_function_single_ipi(int cpu)
+{
+ if (call_function_single_prep_ipi(cpu)) {
+ trace_ipi_send_cpu(cpu, _RET_IP_,
+ generic_smp_call_function_single_interrupt);
+ arch_send_call_function_single_ipi(cpu);
+ }
+}
+
+static __always_inline void
+send_call_function_ipi_mask(struct cpumask *mask)
+{
+ trace_ipi_send_cpumask(mask, _RET_IP_,
+ generic_smp_call_function_single_interrupt);
+ arch_send_call_function_ipi_mask(mask);
+}
+
#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
-static DEFINE_STATIC_KEY_FALSE(csdlock_debug_enabled);
-static DEFINE_STATIC_KEY_FALSE(csdlock_debug_extended);
+static DEFINE_STATIC_KEY_MAYBE(CONFIG_CSD_LOCK_WAIT_DEBUG_DEFAULT, csdlock_debug_enabled);
+/*
+ * Parse the csdlock_debug= kernel boot parameter.
+ *
+ * If you need to restore the old "ext" value that once provided
+ * additional debugging information, reapply the following commits:
+ *
+ * de7b09ef658d ("locking/csd_lock: Prepare more CSD lock debugging")
+ * a5aabace5fb8 ("locking/csd_lock: Add more data to CSD lock debugging")
+ */
static int __init csdlock_debug(char *str)
{
+ int ret;
unsigned int val = 0;
- if (str && !strcmp(str, "ext")) {
- val = 1;
- static_branch_enable(&csdlock_debug_extended);
- } else
- get_option(&str, &val);
-
- if (val)
- static_branch_enable(&csdlock_debug_enabled);
+ ret = get_option(&str, &val);
+ if (ret) {
+ if (val)
+ static_branch_enable(&csdlock_debug_enabled);
+ else
+ static_branch_disable(&csdlock_debug_enabled);
+ }
return 1;
}
static DEFINE_PER_CPU(call_single_data_t *, cur_csd);
static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func);
static DEFINE_PER_CPU(void *, cur_csd_info);
-static DEFINE_PER_CPU(struct cfd_seq_local, cfd_seq_local);
static ulong csd_lock_timeout = 5000; /* CSD lock timeout in milliseconds. */
module_param(csd_lock_timeout, ulong, 0444);
static atomic_t csd_bug_count = ATOMIC_INIT(0);
-static u64 cfd_seq;
-
-#define CFD_SEQ(s, d, t, c) \
- (union cfd_seq_cnt){ .u.src = s, .u.dst = d, .u.type = t, .u.cnt = c }
-
-static u64 cfd_seq_inc(unsigned int src, unsigned int dst, unsigned int type)
-{
- union cfd_seq_cnt new, old;
-
- new = CFD_SEQ(src, dst, type, 0);
-
- do {
- old.val = READ_ONCE(cfd_seq);
- new.u.cnt = old.u.cnt + 1;
- } while (cmpxchg(&cfd_seq, old.val, new.val) != old.val);
-
- return old.val;
-}
-
-#define cfd_seq_store(var, src, dst, type) \
- do { \
- if (static_branch_unlikely(&csdlock_debug_extended)) \
- var = cfd_seq_inc(src, dst, type); \
- } while (0)
/* Record current CSD work for current CPU, NULL to erase. */
static void __csd_lock_record(struct __call_single_data *csd)
return -1;
}
-static void cfd_seq_data_add(u64 val, unsigned int src, unsigned int dst,
- unsigned int type, union cfd_seq_cnt *data,
- unsigned int *n_data, unsigned int now)
-{
- union cfd_seq_cnt new[2];
- unsigned int i, j, k;
-
- new[0].val = val;
- new[1] = CFD_SEQ(src, dst, type, new[0].u.cnt + 1);
-
- for (i = 0; i < 2; i++) {
- if (new[i].u.cnt <= now)
- new[i].u.cnt |= 0x80000000U;
- for (j = 0; j < *n_data; j++) {
- if (new[i].u.cnt == data[j].u.cnt) {
- /* Direct read value trumps generated one. */
- if (i == 0)
- data[j].val = new[i].val;
- break;
- }
- if (new[i].u.cnt < data[j].u.cnt) {
- for (k = *n_data; k > j; k--)
- data[k].val = data[k - 1].val;
- data[j].val = new[i].val;
- (*n_data)++;
- break;
- }
- }
- if (j == *n_data) {
- data[j].val = new[i].val;
- (*n_data)++;
- }
- }
-}
-
-static const char *csd_lock_get_type(unsigned int type)
-{
- return (type >= ARRAY_SIZE(seq_type)) ? "?" : seq_type[type];
-}
-
-static void csd_lock_print_extended(struct __call_single_data *csd, int cpu)
-{
- struct cfd_seq_local *seq = &per_cpu(cfd_seq_local, cpu);
- unsigned int srccpu = csd->node.src;
- struct call_function_data *cfd = per_cpu_ptr(&cfd_data, srccpu);
- struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
- unsigned int now;
- union cfd_seq_cnt data[2 * ARRAY_SIZE(seq_type)];
- unsigned int n_data = 0, i;
-
- data[0].val = READ_ONCE(cfd_seq);
- now = data[0].u.cnt;
-
- cfd_seq_data_add(pcpu->seq_queue, srccpu, cpu, CFD_SEQ_QUEUE, data, &n_data, now);
- cfd_seq_data_add(pcpu->seq_ipi, srccpu, cpu, CFD_SEQ_IPI, data, &n_data, now);
- cfd_seq_data_add(pcpu->seq_noipi, srccpu, cpu, CFD_SEQ_NOIPI, data, &n_data, now);
-
- cfd_seq_data_add(per_cpu(cfd_seq_local.ping, srccpu), srccpu, CFD_SEQ_NOCPU, CFD_SEQ_PING, data, &n_data, now);
- cfd_seq_data_add(per_cpu(cfd_seq_local.pinged, srccpu), srccpu, CFD_SEQ_NOCPU, CFD_SEQ_PINGED, data, &n_data, now);
-
- cfd_seq_data_add(seq->idle, CFD_SEQ_NOCPU, cpu, CFD_SEQ_IDLE, data, &n_data, now);
- cfd_seq_data_add(seq->gotipi, CFD_SEQ_NOCPU, cpu, CFD_SEQ_GOTIPI, data, &n_data, now);
- cfd_seq_data_add(seq->handle, CFD_SEQ_NOCPU, cpu, CFD_SEQ_HANDLE, data, &n_data, now);
- cfd_seq_data_add(seq->dequeue, CFD_SEQ_NOCPU, cpu, CFD_SEQ_DEQUEUE, data, &n_data, now);
- cfd_seq_data_add(seq->hdlend, CFD_SEQ_NOCPU, cpu, CFD_SEQ_HDLEND, data, &n_data, now);
-
- for (i = 0; i < n_data; i++) {
- pr_alert("\tcsd: cnt(%07x): %04x->%04x %s\n",
- data[i].u.cnt & ~0x80000000U, data[i].u.src,
- data[i].u.dst, csd_lock_get_type(data[i].u.type));
- }
- pr_alert("\tcsd: cnt now: %07x\n", now);
-}
-
/*
* Complain if too much time spent waiting. Note that only
* the CSD_TYPE_SYNC/ASYNC types provide the destination CPU,
*bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request");
}
if (cpu >= 0) {
- if (static_branch_unlikely(&csdlock_debug_extended))
- csd_lock_print_extended(csd, cpu);
dump_cpu_task(cpu);
if (!cpu_cur_csd) {
pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu);
smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
}
-
-static void __smp_call_single_queue_debug(int cpu, struct llist_node *node)
-{
- unsigned int this_cpu = smp_processor_id();
- struct cfd_seq_local *seq = this_cpu_ptr(&cfd_seq_local);
- struct call_function_data *cfd = this_cpu_ptr(&cfd_data);
- struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
-
- cfd_seq_store(pcpu->seq_queue, this_cpu, cpu, CFD_SEQ_QUEUE);
- if (llist_add(node, &per_cpu(call_single_queue, cpu))) {
- cfd_seq_store(pcpu->seq_ipi, this_cpu, cpu, CFD_SEQ_IPI);
- cfd_seq_store(seq->ping, this_cpu, cpu, CFD_SEQ_PING);
- send_call_function_single_ipi(cpu);
- cfd_seq_store(seq->pinged, this_cpu, cpu, CFD_SEQ_PINGED);
- } else {
- cfd_seq_store(pcpu->seq_noipi, this_cpu, cpu, CFD_SEQ_NOIPI);
- }
-}
#else
-#define cfd_seq_store(var, src, dst, type)
-
static void csd_lock_record(struct __call_single_data *csd)
{
}
void __smp_call_single_queue(int cpu, struct llist_node *node)
{
-#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
- if (static_branch_unlikely(&csdlock_debug_extended)) {
- unsigned int type;
-
- type = CSD_TYPE(container_of(node, call_single_data_t,
- node.llist));
- if (type == CSD_TYPE_SYNC || type == CSD_TYPE_ASYNC) {
- __smp_call_single_queue_debug(cpu, node);
- return;
- }
+ /*
+ * We have to check the type of the CSD before queueing it, because
+ * once queued it can have its flags cleared by
+ * flush_smp_call_function_queue()
+ * even if we haven't sent the smp_call IPI yet (e.g. the stopper
+ * executes migration_cpu_stop() on the remote CPU).
+ */
+ if (trace_ipi_send_cpu_enabled()) {
+ call_single_data_t *csd;
+ smp_call_func_t func;
+
+ csd = container_of(node, call_single_data_t, node.llist);
+ func = CSD_TYPE(csd) == CSD_TYPE_TTWU ?
+ sched_ttwu_pending : csd->func;
+
+ trace_ipi_send_cpu(cpu, _RET_IP_, func);
}
-#endif
/*
- * The list addition should be visible before sending the IPI
- * handler locks the list to pull the entry off it because of
- * normal cache coherency rules implied by spinlocks.
+ * The list addition should be visible to the target CPU when it pops
+ * the head of the list to pull the entry off it in the IPI handler
+ * because of normal cache coherency rules implied by the underlying
+ * llist ops.
*
* If IPIs can go out of order to the cache coherency protocol
* in an architecture, sufficient synchronisation should be added
*/
void generic_smp_call_function_single_interrupt(void)
{
- cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->gotipi, CFD_SEQ_NOCPU,
- smp_processor_id(), CFD_SEQ_GOTIPI);
__flush_smp_call_function_queue(true);
}
lockdep_assert_irqs_disabled();
head = this_cpu_ptr(&call_single_queue);
- cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->handle, CFD_SEQ_NOCPU,
- smp_processor_id(), CFD_SEQ_HANDLE);
entry = llist_del_all(head);
- cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->dequeue,
- /* Special meaning of source cpu: 0 == queue empty */
- entry ? CFD_SEQ_NOCPU : 0,
- smp_processor_id(), CFD_SEQ_DEQUEUE);
entry = llist_reverse_order(entry);
/* There shouldn't be any pending callbacks on an offline CPU. */
}
}
- if (!entry) {
- cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->hdlend,
- 0, smp_processor_id(),
- CFD_SEQ_HDLEND);
+ if (!entry)
return;
- }
/*
* Second; run all !SYNC callbacks.
*/
if (entry)
sched_ttwu_pending(entry);
-
- cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->hdlend, CFD_SEQ_NOCPU,
- smp_processor_id(), CFD_SEQ_HDLEND);
}
if (llist_empty(this_cpu_ptr(&call_single_queue)))
return;
- cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->idle, CFD_SEQ_NOCPU,
- smp_processor_id(), CFD_SEQ_IDLE);
local_irq_save(flags);
/* Get the already pending soft interrupts for RT enabled kernels */
was_pending = local_softirq_pending();
int cpu, last_cpu, this_cpu = smp_processor_id();
struct call_function_data *cfd;
bool wait = scf_flags & SCF_WAIT;
+ int nr_cpus = 0, nr_queued = 0;
bool run_remote = false;
bool run_local = false;
- int nr_cpus = 0;
lockdep_assert_preemption_disabled();
cpumask_clear(cfd->cpumask_ipi);
for_each_cpu(cpu, cfd->cpumask) {
- struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
- call_single_data_t *csd = &pcpu->csd;
+ call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
- if (cond_func && !cond_func(cpu, info))
+ if (cond_func && !cond_func(cpu, info)) {
+ __cpumask_clear_cpu(cpu, cfd->cpumask);
continue;
+ }
csd_lock(csd);
if (wait)
csd->node.src = smp_processor_id();
csd->node.dst = cpu;
#endif
- cfd_seq_store(pcpu->seq_queue, this_cpu, cpu, CFD_SEQ_QUEUE);
if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) {
__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
nr_cpus++;
last_cpu = cpu;
-
- cfd_seq_store(pcpu->seq_ipi, this_cpu, cpu, CFD_SEQ_IPI);
- } else {
- cfd_seq_store(pcpu->seq_noipi, this_cpu, cpu, CFD_SEQ_NOIPI);
}
+ nr_queued++;
}
- cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->ping, this_cpu, CFD_SEQ_NOCPU, CFD_SEQ_PING);
+ /*
+ * Trace each smp_function_call_*() as an IPI, actual IPIs
+ * will be traced with func==generic_smp_call_function_single_ipi().
+ */
+ if (nr_queued)
+ trace_ipi_send_cpumask(cfd->cpumask, _RET_IP_, func);
/*
* Choose the most efficient way to send an IPI. Note that the
if (nr_cpus == 1)
send_call_function_single_ipi(last_cpu);
else if (likely(nr_cpus > 1))
- arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
-
- cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->pinged, this_cpu, CFD_SEQ_NOCPU, CFD_SEQ_PINGED);
+ send_call_function_ipi_mask(cfd->cpumask_ipi);
}
if (run_local && (!cond_func || cond_func(this_cpu, info))) {
for_each_cpu(cpu, cfd->cpumask) {
call_single_data_t *csd;
- csd = &per_cpu_ptr(cfd->pcpu, cpu)->csd;
+ csd = per_cpu_ptr(cfd->csd, cpu);
csd_lock_wait(csd);
}
}
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