---

yaml
---
r: 147302
b: refs/heads/master
c: 925d519
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 53cfbf593758916aac41db728f029986a62f1254
+refs/heads/master: 925d519ab82b6dd7aca9420d809ee83819c08db2

trunk/arch/powerpc/include/asm/hw_irq.h

@@ -132,7 +132,7 @@ static inline int irqs_disabled_flags(unsigned long flags)
 struct irq_chip;
 
 #ifdef CONFIG_PERF_COUNTERS
-static inline unsigned long get_perf_counter_pending(void)
+static inline unsigned long test_perf_counter_pending(void)
 {
 	unsigned long x;
 
@@ -160,7 +160,7 @@ extern void perf_counter_do_pending(void);
 
 #else
 
-static inline unsigned long get_perf_counter_pending(void)
+static inline unsigned long test_perf_counter_pending(void)
 {
 	return 0;
 }

trunk/arch/powerpc/kernel/irq.c

@@ -135,7 +135,7 @@ notrace void raw_local_irq_restore(unsigned long en)
 			iseries_handle_interrupts();
 	}
 
-	if (get_perf_counter_pending()) {
+	if (test_perf_counter_pending()) {
 		clear_perf_counter_pending();
 		perf_counter_do_pending();
 	}

trunk/arch/powerpc/kernel/perf_counter.c

@@ -649,24 +649,6 @@ hw_perf_counter_init(struct perf_counter *counter)
 	return &power_perf_ops;
 }
 
-/*
- * Handle wakeups.
- */
-void perf_counter_do_pending(void)
-{
-	int i;
-	struct cpu_hw_counters *cpuhw = &__get_cpu_var(cpu_hw_counters);
-	struct perf_counter *counter;
-
-	for (i = 0; i < cpuhw->n_counters; ++i) {
-		counter = cpuhw->counter[i];
-		if (counter && counter->wakeup_pending) {
-			counter->wakeup_pending = 0;
-			wake_up(&counter->waitq);
-		}
-	}
-}
-
 /*
  * A counter has overflowed; update its count and record
  * things if requested.  Note that interrupts are hard-disabled
@@ -720,7 +702,7 @@ static void perf_counter_interrupt(struct pt_regs *regs)
 	struct cpu_hw_counters *cpuhw = &__get_cpu_var(cpu_hw_counters);
 	struct perf_counter *counter;
 	long val;
-	int need_wakeup = 0, found = 0;
+	int found = 0;
 
 	for (i = 0; i < cpuhw->n_counters; ++i) {
 		counter = cpuhw->counter[i];
@@ -761,7 +743,7 @@ static void perf_counter_interrupt(struct pt_regs *regs)
 	 * immediately; otherwise we'll have do the wakeup when interrupts
 	 * get soft-enabled.
 	 */
-	if (get_perf_counter_pending() && regs->softe) {
+	if (test_perf_counter_pending() && regs->softe) {
 		irq_enter();
 		clear_perf_counter_pending();
 		perf_counter_do_pending();

trunk/arch/x86/include/asm/perf_counter.h

@@ -84,8 +84,9 @@ union cpuid10_edx {
 #define MSR_ARCH_PERFMON_FIXED_CTR2			0x30b
 #define X86_PMC_IDX_FIXED_BUS_CYCLES			(X86_PMC_IDX_FIXED + 2)
 
-#define set_perf_counter_pending()	\
-		set_tsk_thread_flag(current, TIF_PERF_COUNTERS);
+#define set_perf_counter_pending()	do { } while (0)
+#define clear_perf_counter_pending()	do { } while (0)
+#define test_perf_counter_pending()	(0)
 
 #ifdef CONFIG_PERF_COUNTERS
 extern void init_hw_perf_counters(void);

trunk/arch/x86/include/asm/thread_info.h

@@ -83,7 +83,6 @@ struct thread_info {
 #define TIF_SYSCALL_AUDIT	7	/* syscall auditing active */
 #define TIF_SECCOMP		8	/* secure computing */
 #define TIF_MCE_NOTIFY		10	/* notify userspace of an MCE */
-#define TIF_PERF_COUNTERS	11	/* notify perf counter work */
 #define TIF_NOTSC		16	/* TSC is not accessible in userland */
 #define TIF_IA32		17	/* 32bit process */
 #define TIF_FORK		18	/* ret_from_fork */
@@ -107,7 +106,6 @@ struct thread_info {
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 #define _TIF_MCE_NOTIFY		(1 << TIF_MCE_NOTIFY)
-#define _TIF_PERF_COUNTERS	(1 << TIF_PERF_COUNTERS)
 #define _TIF_NOTSC		(1 << TIF_NOTSC)
 #define _TIF_IA32		(1 << TIF_IA32)
 #define _TIF_FORK		(1 << TIF_FORK)
@@ -141,7 +139,7 @@ struct thread_info {
 
 /* Only used for 64 bit */
 #define _TIF_DO_NOTIFY_MASK						\
-	(_TIF_SIGPENDING|_TIF_MCE_NOTIFY|_TIF_PERF_COUNTERS|_TIF_NOTIFY_RESUME)
+	(_TIF_SIGPENDING|_TIF_MCE_NOTIFY|_TIF_NOTIFY_RESUME)
 
 /* flags to check in __switch_to() */
 #define _TIF_WORK_CTXSW							\

trunk/arch/x86/kernel/cpu/perf_counter.c

@@ -227,7 +227,6 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
 		 */
 		hwc->config |= pmc_ops->event_map(perf_event_id(hw_event));
 	}
-	counter->wakeup_pending = 0;
 
 	return 0;
 }
@@ -773,34 +772,6 @@ void smp_perf_counter_interrupt(struct pt_regs *regs)
 	irq_exit();
 }
 
-/*
- * This handler is triggered by NMI contexts:
- */
-void perf_counter_notify(struct pt_regs *regs)
-{
-	struct cpu_hw_counters *cpuc;
-	unsigned long flags;
-	int bit, cpu;
-
-	local_irq_save(flags);
-	cpu = smp_processor_id();
-	cpuc = &per_cpu(cpu_hw_counters, cpu);
-
-	for_each_bit(bit, cpuc->used, X86_PMC_IDX_MAX) {
-		struct perf_counter *counter = cpuc->counters[bit];
-
-		if (!counter)
-			continue;
-
-		if (counter->wakeup_pending) {
-			counter->wakeup_pending = 0;
-			wake_up(&counter->waitq);
-		}
-	}
-
-	local_irq_restore(flags);
-}
-
 void perf_counters_lapic_init(int nmi)
 {
 	u32 apic_val;

trunk/arch/x86/kernel/signal.c

@@ -6,7 +6,6 @@
  *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
  *  2000-2002   x86-64 support by Andi Kleen
  */
-#include <linux/perf_counter.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
@@ -872,11 +871,6 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 		tracehook_notify_resume(regs);
 	}
 
-	if (thread_info_flags & _TIF_PERF_COUNTERS) {
-		clear_thread_flag(TIF_PERF_COUNTERS);
-		perf_counter_notify(regs);
-	}
-
 #ifdef CONFIG_X86_32
 	clear_thread_flag(TIF_IRET);
 #endif /* CONFIG_X86_32 */

trunk/include/linux/perf_counter.h

@@ -275,6 +275,10 @@ struct perf_mmap_data {
 	void 				*data_pages[0];
 };
 
+struct perf_wakeup_entry {
+	struct perf_wakeup_entry *next;
+};
+
 /**
  * struct perf_counter - performance counter kernel representation:
  */
@@ -350,7 +354,7 @@ struct perf_counter {
 	/* poll related */
 	wait_queue_head_t		waitq;
 	/* optional: for NMIs */
-	int				wakeup_pending;
+	struct perf_wakeup_entry	wakeup;
 
 	void (*destroy)(struct perf_counter *);
 	struct rcu_head			rcu_head;
@@ -427,7 +431,7 @@ extern void perf_counter_task_sched_out(struct task_struct *task, int cpu);
 extern void perf_counter_task_tick(struct task_struct *task, int cpu);
 extern void perf_counter_init_task(struct task_struct *child);
 extern void perf_counter_exit_task(struct task_struct *child);
-extern void perf_counter_notify(struct pt_regs *regs);
+extern void perf_counter_do_pending(void);
 extern void perf_counter_print_debug(void);
 extern void perf_counter_unthrottle(void);
 extern u64 hw_perf_save_disable(void);
@@ -461,16 +465,17 @@ static inline void
 perf_counter_task_tick(struct task_struct *task, int cpu)		{ }
 static inline void perf_counter_init_task(struct task_struct *child)	{ }
 static inline void perf_counter_exit_task(struct task_struct *child)	{ }
-static inline void perf_counter_notify(struct pt_regs *regs)		{ }
+static inline void perf_counter_do_pending(void)			{ }
 static inline void perf_counter_print_debug(void)			{ }
 static inline void perf_counter_unthrottle(void)			{ }
 static inline void hw_perf_restore(u64 ctrl)				{ }
 static inline u64 hw_perf_save_disable(void)		      { return 0; }
 static inline int perf_counter_task_disable(void)	{ return -EINVAL; }
 static inline int perf_counter_task_enable(void)	{ return -EINVAL; }
 
-static inline void perf_swcounter_event(u32 event, u64 nr,
-					int nmi, struct pt_regs *regs)	{ }
+static inline void
+perf_swcounter_event(u32 event, u64 nr, int nmi, struct pt_regs *regs)	{ }
+
 #endif
 
 #endif /* __KERNEL__ */

trunk/kernel/perf_counter.c

@@ -1197,8 +1197,12 @@ static void free_counter_rcu(struct rcu_head *head)
 	kfree(counter);
 }
 
+static void perf_pending_sync(struct perf_counter *counter);
+
 static void free_counter(struct perf_counter *counter)
 {
+	perf_pending_sync(counter);
+
 	if (counter->destroy)
 		counter->destroy(counter);
 
@@ -1528,6 +1532,118 @@ static const struct file_operations perf_fops = {
 	.mmap			= perf_mmap,
 };
 
+/*
+ * Perf counter wakeup
+ *
+ * If there's data, ensure we set the poll() state and publish everything
+ * to user-space before waking everybody up.
+ */
+
+void perf_counter_wakeup(struct perf_counter *counter)
+{
+	struct perf_mmap_data *data;
+
+	rcu_read_lock();
+	data = rcu_dereference(counter->data);
+	if (data) {
+		(void)atomic_xchg(&data->wakeup, POLL_IN);
+		__perf_counter_update_userpage(counter, data);
+	}
+	rcu_read_unlock();
+
+	wake_up_all(&counter->waitq);
+}
+
+/*
+ * Pending wakeups
+ *
+ * Handle the case where we need to wakeup up from NMI (or rq->lock) context.
+ *
+ * The NMI bit means we cannot possibly take locks. Therefore, maintain a
+ * single linked list and use cmpxchg() to add entries lockless.
+ */
+
+#define PENDING_TAIL ((struct perf_wakeup_entry *)-1UL)
+
+static DEFINE_PER_CPU(struct perf_wakeup_entry *, perf_wakeup_head) = {
+	PENDING_TAIL,
+};
+
+static void perf_pending_queue(struct perf_counter *counter)
+{
+	struct perf_wakeup_entry **head;
+	struct perf_wakeup_entry *prev, *next;
+
+	if (cmpxchg(&counter->wakeup.next, NULL, PENDING_TAIL) != NULL)
+		return;
+
+	head = &get_cpu_var(perf_wakeup_head);
+
+	do {
+		prev = counter->wakeup.next = *head;
+		next = &counter->wakeup;
+	} while (cmpxchg(head, prev, next) != prev);
+
+	set_perf_counter_pending();
+
+	put_cpu_var(perf_wakeup_head);
+}
+
+static int __perf_pending_run(void)
+{
+	struct perf_wakeup_entry *list;
+	int nr = 0;
+
+	list = xchg(&__get_cpu_var(perf_wakeup_head), PENDING_TAIL);
+	while (list != PENDING_TAIL) {
+		struct perf_counter *counter = container_of(list,
+				struct perf_counter, wakeup);
+
+		list = list->next;
+
+		counter->wakeup.next = NULL;
+		/*
+		 * Ensure we observe the unqueue before we issue the wakeup,
+		 * so that we won't be waiting forever.
+		 * -- see perf_not_pending().
+		 */
+		smp_wmb();
+
+		perf_counter_wakeup(counter);
+		nr++;
+	}
+
+	return nr;
+}
+
+static inline int perf_not_pending(struct perf_counter *counter)
+{
+	/*
+	 * If we flush on whatever cpu we run, there is a chance we don't
+	 * need to wait.
+	 */
+	get_cpu();
+	__perf_pending_run();
+	put_cpu();
+
+	/*
+	 * Ensure we see the proper queue state before going to sleep
+	 * so that we do not miss the wakeup. -- see perf_pending_handle()
+	 */
+	smp_rmb();
+	return counter->wakeup.next == NULL;
+}
+
+static void perf_pending_sync(struct perf_counter *counter)
+{
+	wait_event(counter->waitq, perf_not_pending(counter));
+}
+
+void perf_counter_do_pending(void)
+{
+	__perf_pending_run();
+}
+
 /*
  * Output
  */
@@ -1611,13 +1727,10 @@ static void perf_output_copy(struct perf_output_handle *handle,
 static void perf_output_end(struct perf_output_handle *handle, int nmi)
 {
 	if (handle->wakeup) {
-		(void)atomic_xchg(&handle->data->wakeup, POLL_IN);
-		__perf_counter_update_userpage(handle->counter, handle->data);
-		if (nmi) {
-			handle->counter->wakeup_pending = 1;
-			set_perf_counter_pending();
-		} else
-			wake_up(&handle->counter->waitq);
+		if (nmi)
+			perf_pending_queue(handle->counter);
+		else
+			perf_counter_wakeup(handle->counter);
 	}
 	rcu_read_unlock();
 }
@@ -2211,7 +2324,6 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event,
 
 	counter->cpu			= cpu;
 	counter->hw_event		= *hw_event;
-	counter->wakeup_pending		= 0;
 	counter->group_leader		= group_leader;
 	counter->hw_ops			= NULL;
 	counter->ctx			= ctx;

trunk/kernel/timer.c

@@ -37,6 +37,7 @@
 #include <linux/delay.h>
 #include <linux/tick.h>
 #include <linux/kallsyms.h>
+#include <linux/perf_counter.h>
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -1167,6 +1168,8 @@ static void run_timer_softirq(struct softirq_action *h)
 {
 	struct tvec_base *base = __get_cpu_var(tvec_bases);
 
+	perf_counter_do_pending();
+
 	hrtimer_run_pending();
 
 	if (time_after_eq(jiffies, base->timer_jiffies))