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SMP cross-CPU function-call updates for v6.4:

Browse Source 
- Remove diagnostics and adjust config for CSD lock diagnostics
 
  - Add a generic IPI-sending tracepoint, as currently there's no easy
    way to instrument IPI origins: it's arch dependent and for some
    major architectures it's not even consistently available.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull SMP cross-CPU function-call updates from Ingo Molnar:

 - Remove diagnostics and adjust config for CSD lock diagnostics

 - Add a generic IPI-sending tracepoint, as currently there's no easy
   way to instrument IPI origins: it's arch dependent and for some major
   architectures it's not even consistently available.

* tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  trace,smp: Trace all smp_function_call*() invocations
  trace: Add trace_ipi_send_cpu()
  sched, smp: Trace smp callback causing an IPI
  smp: reword smp call IPI comment
  treewide: Trace IPIs sent via smp_send_reschedule()
  irq_work: Trace self-IPIs sent via arch_irq_work_raise()
  smp: Trace IPIs sent via arch_send_call_function_ipi_mask()
  sched, smp: Trace IPIs sent via send_call_function_single_ipi()
  trace: Add trace_ipi_send_cpumask()
  kernel/smp: Make csdlock_debug= resettable
  locking/csd_lock: Remove per-CPU data indirection from CSD lock debugging
  locking/csd_lock: Remove added data from CSD lock debugging
  locking/csd_lock: Add Kconfig option for csd_debug default
This commit is contained in:
Linus Torvalds 2023-04-28 15:03:43 -07:00
commit f20730efbd
33 changed files with 216 additions and 280 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
Documentation/admin-guide/kernel-parameters.txt
View File

@ -912,15 +912,14 @@
cs89x0_media= [HW,NET]
Format: { rj45 | aui | bnc }
csdlock_debug= [KNL] Enable debug add-ons of cross-CPU function call
handling. When switched on, additional debug data is
printed to the console in case a hanging CPU is
detected, and that CPU is pinged again in order to try
to resolve the hang situation.
0: disable csdlock debugging (default)
1: enable basic csdlock debugging (minor impact)
ext: enable extended csdlock debugging (more impact,
but more data)
csdlock_debug= [KNL] Enable or disable debug add-ons of cross-CPU
function call handling. When switched on,
additional debug data is printed to the console
in case a hanging CPU is detected, and that
CPU is pinged again in order to try to resolve
the hang situation. The default value of this
option depends on the CSD_LOCK_WAIT_DEBUG_DEFAULT
Kconfig option.
dasd= [HW,NET]
See header of drivers/s390/block/dasd_devmap.c.

2
arch/alpha/kernel/smp.c
View File

@ -562,7 +562,7 @@ handle_ipi(struct pt_regs *regs)
}
void
smp_send_reschedule(int cpu)
arch_smp_send_reschedule(int cpu)
{
#ifdef DEBUG_IPI_MSG
if (cpu == hard_smp_processor_id())

2
arch/arc/kernel/smp.c
View File

@ -292,7 +292,7 @@ static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
ipi_send_msg_one(cpu, msg);
}
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
ipi_send_msg_one(cpu, IPI_RESCHEDULE);
}

3
arch/arm/kernel/smp.c
View File

@ -48,7 +48,6 @@
#include <asm/mach/arch.h>
#include <asm/mpu.h>
#define CREATE_TRACE_POINTS
#include <trace/events/ipi.h>
/*
@ -749,7 +748,7 @@ void __init set_smp_ipi_range(int ipi_base, int n)
ipi_setup(smp_processor_id());
}
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
}

2
arch/arm/mach-actions/platsmp.c
View File

@ -20,6 +20,8 @@
#include <asm/smp_plat.h>
#include <asm/smp_scu.h>
#include <trace/events/ipi.h>
#define OWL_CPU1_ADDR 0x50
#define OWL_CPU1_FLAG 0x5c

3
arch/arm64/kernel/smp.c
View File

@ -51,7 +51,6 @@
#include <asm/ptrace.h>
#include <asm/virt.h>
#define CREATE_TRACE_POINTS
#include <trace/events/ipi.h>
DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
@ -979,7 +978,7 @@ void __init set_smp_ipi_range(int ipi_base, int n)
ipi_setup(smp_processor_id());
}
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
}

2
arch/csky/kernel/smp.c
View File

@ -140,7 +140,7 @@ void smp_send_stop(void)
on_each_cpu(ipi_stop, NULL, 1);
}
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE);
}

2
arch/hexagon/kernel/smp.c
View File

@ -217,7 +217,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
}
}
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
send_ipi(cpumask_of(cpu), IPI_RESCHEDULE);
}

4
arch/ia64/kernel/smp.c
View File

@ -220,11 +220,11 @@ kdump_smp_send_init(void)
* Called with preemption disabled.
*/
void
smp_send_reschedule (int cpu)
arch_smp_send_reschedule (int cpu)
{
ia64_send_ipi(cpu, IA64_IPI_RESCHEDULE, IA64_IPI_DM_INT, 0);
}
EXPORT_SYMBOL_GPL(smp_send_reschedule);
EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);
/*
* Called with preemption disabled.

4
arch/loongarch/kernel/smp.c
View File

@ -155,11 +155,11 @@ void loongson_send_ipi_mask(const struct cpumask *mask, unsigned int action)
* it goes straight through and wastes no time serializing
* anything. Worst case is that we lose a reschedule ...
*/
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
loongson_send_ipi_single(cpu, SMP_RESCHEDULE);
}
EXPORT_SYMBOL_GPL(smp_send_reschedule);
EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);
irqreturn_t loongson_ipi_interrupt(int irq, void *dev)
{

2
arch/mips/include/asm/smp.h
View File

@ -66,7 +66,7 @@ extern void calculate_cpu_foreign_map(void);
* it goes straight through and wastes no time serializing
* anything. Worst case is that we lose a reschedule ...
*/
static inline void smp_send_reschedule(int cpu)
static inline void arch_smp_send_reschedule(int cpu)
{
extern const struct plat_smp_ops *mp_ops; /* private */

2
arch/openrisc/kernel/smp.c
View File

@ -173,7 +173,7 @@ void handle_IPI(unsigned int ipi_msg)
}
}
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
}

4
arch/parisc/kernel/smp.c
View File

@ -246,8 +246,8 @@ void kgdb_roundup_cpus(void)
inline void
smp_send_stop(void) { send_IPI_allbutself(IPI_CPU_STOP); }
void
smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
void
arch_smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
void
smp_send_all_nop(void)

6
arch/powerpc/kernel/smp.c
View File

@ -61,6 +61,8 @@
#include <asm/kup.h>
#include <asm/fadump.h>
#include <trace/events/ipi.h>
#ifdef DEBUG
#include <asm/udbg.h>
#define DBG(fmt...) udbg_printf(fmt)
@ -364,12 +366,12 @@ static inline void do_message_pass(int cpu, int msg)
#endif
}
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
if (likely(smp_ops))
do_message_pass(cpu, PPC_MSG_RESCHEDULE);
}
EXPORT_SYMBOL_GPL(smp_send_reschedule);
EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);
void arch_send_call_function_single_ipi(int cpu)
{

3
arch/powerpc/kvm/book3s_hv.c
View File

@ -43,6 +43,7 @@
#include <linux/compiler.h>
#include <linux/of.h>
#include <linux/irqdomain.h>
#include <linux/smp.h>
#include <asm/ftrace.h>
#include <asm/reg.h>
@ -80,6 +81,8 @@
#include <asm/dtl.h>
#include <asm/plpar_wrappers.h>
#include <trace/events/ipi.h>
#include "book3s.h"
#include "book3s_hv.h"

2
arch/powerpc/platforms/powernv/subcore.c
View File

@ -20,6 +20,8 @@
#include <asm/opal.h>
#include <asm/smp.h>
#include <trace/events/ipi.h>
#include "subcore.h"
#include "powernv.h"

4
arch/riscv/kernel/smp.c
View File

@ -333,8 +333,8 @@ bool smp_crash_stop_failed(void)
}
#endif
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
send_ipi_single(cpu, IPI_RESCHEDULE);
}
EXPORT_SYMBOL_GPL(smp_send_reschedule);
EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);

2
arch/s390/kernel/smp.c
View File

@ -553,7 +553,7 @@ void arch_send_call_function_single_ipi(int cpu)
* it goes straight through and wastes no time serializing
* anything. Worst case is that we lose a reschedule ...
*/
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
pcpu_ec_call(pcpu_devices + cpu, ec_schedule);
}

2
arch/sh/kernel/smp.c
View File

@ -256,7 +256,7 @@ void __init smp_cpus_done(unsigned int max_cpus)
(bogosum / (5000/HZ)) % 100);
}
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
mp_ops->send_ipi(cpu, SMP_MSG_RESCHEDULE);
}

2
arch/sparc/kernel/smp_32.c
View File

@ -120,7 +120,7 @@ void cpu_panic(void)
struct linux_prom_registers smp_penguin_ctable = { 0 };
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
/*
* CPU model dependent way of implementing IPI generation targeting

2
arch/sparc/kernel/smp_64.c
View File

@ -1430,7 +1430,7 @@ static unsigned long send_cpu_poke(int cpu)
return hv_err;
}
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
if (cpu == smp_processor_id()) {
WARN_ON_ONCE(preemptible());

2
arch/x86/include/asm/smp.h
View File

@ -99,7 +99,7 @@ static inline void __noreturn play_dead(void)
BUG();
}
static inline void smp_send_reschedule(int cpu)
static inline void arch_smp_send_reschedule(int cpu)
{
smp_ops.smp_send_reschedule(cpu);
}

4
arch/x86/kvm/svm/svm.c
View File

@ -27,6 +27,7 @@
#include <linux/swap.h>
#include <linux/rwsem.h>
#include <linux/cc_platform.h>
#include <linux/smp.h>
#include <asm/apic.h>
#include <asm/perf_event.h>
@ -41,6 +42,9 @@
#include <asm/fpu/api.h>
#include <asm/virtext.h>
#include <trace/events/ipi.h>
#include "trace.h"
#include "svm.h"

2
arch/x86/kvm/x86.c
View File

@ -60,7 +60,9 @@
#include <linux/mem_encrypt.h>
#include <linux/entry-kvm.h>
#include <linux/suspend.h>
#include <linux/smp.h>
#include <trace/events/ipi.h>
#include <trace/events/kvm.h>
#include <asm/debugreg.h>

2
arch/xtensa/kernel/smp.c
View File

@ -391,7 +391,7 @@ void arch_send_call_function_single_ipi(int cpu)
send_ipi_message(cpumask_of(cpu), IPI_CALL_FUNC);
}
void smp_send_reschedule(int cpu)
void arch_smp_send_reschedule(int cpu)
{
send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE);
}

11
include/linux/smp.h
View File

@ -125,8 +125,15 @@ extern void smp_send_stop(void);
/*
* sends a 'reschedule' event to another CPU:
*/
extern void smp_send_reschedule(int cpu);
extern void arch_smp_send_reschedule(int cpu);
/*
* scheduler_ipi() is inline so can't be passed as callback reason, but the
* callsite IP should be sufficient for root-causing IPIs sent from here.
*/
#define smp_send_reschedule(cpu) ({ \
trace_ipi_send_cpu(cpu, _RET_IP_, NULL); \
arch_smp_send_reschedule(cpu); \
})
/*
* Prepare machine for booting other CPUs.

44
include/trace/events/ipi.h
View File

@ -35,6 +35,50 @@ TRACE_EVENT(ipi_raise,
TP_printk("target_mask=%s (%s)", __get_bitmask(target_cpus), __entry->reason)
);
TRACE_EVENT(ipi_send_cpu,
TP_PROTO(const unsigned int cpu, unsigned long callsite, void *callback),
TP_ARGS(cpu, callsite, callback),
TP_STRUCT__entry(
__field(unsigned int, cpu)
__field(void *, callsite)
__field(void *, callback)
),
TP_fast_assign(
__entry->cpu = cpu;
__entry->callsite = (void *)callsite;
__entry->callback = callback;
),
TP_printk("cpu=%u callsite=%pS callback=%pS",
__entry->cpu, __entry->callsite, __entry->callback)
);
TRACE_EVENT(ipi_send_cpumask,
TP_PROTO(const struct cpumask *cpumask, unsigned long callsite, void *callback),
TP_ARGS(cpumask, callsite, callback),
TP_STRUCT__entry(
__cpumask(cpumask)
__field(void *, callsite)
__field(void *, callback)
),
TP_fast_assign(
__assign_cpumask(cpumask, cpumask_bits(cpumask));
__entry->callsite = (void *)callsite;
__entry->callback = callback;
),
TP_printk("cpumask=%s callsite=%pS callback=%pS",
__get_cpumask(cpumask), __entry->callsite, __entry->callback)
);
DECLARE_EVENT_CLASS(ipi_handler,
TP_PROTO(const char *reason),

12
kernel/irq_work.c
View File

@ -22,6 +22,8 @@
#include <asm/processor.h>
#include <linux/kasan.h>
#include <trace/events/ipi.h>
static DEFINE_PER_CPU(struct llist_head, raised_list);
static DEFINE_PER_CPU(struct llist_head, lazy_list);
static DEFINE_PER_CPU(struct task_struct *, irq_workd);
@ -74,6 +76,14 @@ void __weak arch_irq_work_raise(void)
*/
}
static __always_inline void irq_work_raise(struct irq_work *work)
{
if (trace_ipi_send_cpu_enabled() && arch_irq_work_has_interrupt())
trace_ipi_send_cpu(smp_processor_id(), _RET_IP_, work->func);
arch_irq_work_raise();
}
/* Enqueue on current CPU, work must already be claimed and preempt disabled */
static void __irq_work_queue_local(struct irq_work *work)
{
@ -99,7 +109,7 @@ static void __irq_work_queue_local(struct irq_work *work)
/* If the work is "lazy", handle it from next tick if any */
if (!lazy_work || tick_nohz_tick_stopped())
arch_irq_work_raise();
irq_work_raise(work);
}
/* Enqueue the irq work @work on the current CPU */

22
kernel/sched/core.c
View File

@ -80,6 +80,7 @@
#define CREATE_TRACE_POINTS
#include <linux/sched/rseq_api.h>
#include <trace/events/sched.h>
#include <trace/events/ipi.h>
#undef CREATE_TRACE_POINTS
#include "sched.h"
@ -95,6 +96,9 @@
#include "../../io_uring/io-wq.h"
#include "../smpboot.h"
EXPORT_TRACEPOINT_SYMBOL_GPL(ipi_send_cpu);
EXPORT_TRACEPOINT_SYMBOL_GPL(ipi_send_cpumask);
/*
* Export tracepoints that act as a bare tracehook (ie: have no trace event
* associated with them) to allow external modules to probe them.
@ -3848,14 +3852,20 @@ void sched_ttwu_pending(void *arg)
rq_unlock_irqrestore(rq, &rf);
}
void send_call_function_single_ipi(int cpu)
/*
* Prepare the scene for sending an IPI for a remote smp_call
*
* Returns true if the caller can proceed with sending the IPI.
* Returns false otherwise.
*/
bool call_function_single_prep_ipi(int cpu)
{
struct rq *rq = cpu_rq(cpu);
if (!set_nr_if_polling(rq->idle))
arch_send_call_function_single_ipi(cpu);
else
if (set_nr_if_polling(cpu_rq(cpu)->idle)) {
trace_sched_wake_idle_without_ipi(cpu);
return false;
}
return true;
}
/*

2
kernel/sched/smp.h
View File

@ -6,7 +6,7 @@
extern void sched_ttwu_pending(void *arg);
extern void send_call_function_single_ipi(int cpu);
extern bool call_function_single_prep_ipi(int cpu);
#ifdef CONFIG_SMP
extern void flush_smp_call_function_queue(void);

311
kernel/smp.c
View File

@ -26,68 +26,15 @@
#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;
};
@ -110,8 +57,8 @@ int smpcfd_prepare_cpu(unsigned int cpu)
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;
@ -126,7 +73,7 @@ int smpcfd_dead_cpu(unsigned int cpu)
free_cpumask_var(cfd->cpumask);
free_cpumask_var(cfd->cpumask_ipi);
free_percpu(cfd->pcpu);
free_percpu(cfd->csd);
return 0;
}
@ -156,23 +103,49 @@ void __init call_function_init(void)
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;
}
@ -181,36 +154,11 @@ __setup("csdlock_debug=", csdlock_debug);
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)
@ -244,80 +192,6 @@ static int csd_lock_wait_getcpu(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,
@ -368,8 +242,6 @@ static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 *
*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);
@ -412,27 +284,7 @@ static __always_inline void csd_lock_wait(struct __call_single_data *csd)
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)
{
}
@ -470,23 +322,29 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
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;
/*
* 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;
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;
}
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
@ -541,8 +399,6 @@ static int generic_exec_single(int cpu, struct __call_single_data *csd)
*/
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);
}
@ -570,13 +426,7 @@ static void __flush_smp_call_function_queue(bool warn_cpu_offline)
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. */
@ -635,12 +485,8 @@ static void __flush_smp_call_function_queue(bool warn_cpu_offline)
}
}
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.
@ -678,9 +524,6 @@ static void __flush_smp_call_function_queue(bool warn_cpu_offline)
*/
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);
}
@ -704,8 +547,6 @@ void flush_smp_call_function_queue(void)
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();
@ -887,9 +728,9 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
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();
@ -929,11 +770,12 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
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)
@ -944,19 +786,20 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
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
@ -966,9 +809,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
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))) {
@ -983,7 +824,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
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);
}
}

9
lib/Kconfig.debug
View File

@ -1490,6 +1490,15 @@ config CSD_LOCK_WAIT_DEBUG
include the IPI handler function currently executing (if any)
and relevant stack traces.
config CSD_LOCK_WAIT_DEBUG_DEFAULT
bool "Default csd_lock_wait() debugging on at boot time"
depends on CSD_LOCK_WAIT_DEBUG
depends on 64BIT
default n
help
This option causes the csdlock_debug= kernel boot parameter to
default to 1 (basic debugging) instead of 0 (no debugging).
endmenu # lock debugging
config TRACE_IRQFLAGS

3
virt/kvm/kvm_main.c
View File

@ -62,11 +62,14 @@
#include "kvm_mm.h"
#include "vfio.h"
#include <trace/events/ipi.h>
#define CREATE_TRACE_POINTS
#include <trace/events/kvm.h>
#include <linux/kvm_dirty_ring.h>
/* Worst case buffer size needed for holding an integer. */
#define ITOA_MAX_LEN 12