perf_counter: counter overflow limit (79f14641) · Commits · 戴 / test

include/linux/perf_counter.h

+9 −3

Original line number	Diff line number	Diff line
		@@ -157,6 +157,7 @@ struct perf_counter_hw_event {
		*/
		#define PERF_COUNTER_IOC_ENABLE _IO ('$', 0)
		#define PERF_COUNTER_IOC_DISABLE _IO ('$', 1)
		#define PERF_COUNTER_IOC_REFRESH _IOW('$', 2, u32)

		/*
		* Structure of the page that can be mapped via mmap
		@@ -403,9 +404,14 @@ struct perf_counter {
		/* poll related */
		wait_queue_head_t waitq;
		struct fasync_struct *fasync;
		/* optional: for NMIs */

		/* delayed work for NMIs and such */
		int pending_wakeup;
		int pending_disable;
		struct perf_pending_entry pending;

		atomic_t event_limit;

		void (destroy)(struct perf_counter );
		struct rcu_head rcu_head;
		#endif

kernel/perf_counter.c

+41 −10

Original line number	Diff line number	Diff line
		@@ -744,6 +744,12 @@ static void perf_counter_enable(struct perf_counter *counter)
		spin_unlock_irq(&ctx->lock);
		}

		static void perf_counter_refresh(struct perf_counter *counter, int refresh)
		{
		atomic_add(refresh, &counter->event_limit);
		perf_counter_enable(counter);
		}

		/*
		* Enable a counter and all its children.
		*/
		@@ -1311,6 +1317,9 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
		case PERF_COUNTER_IOC_DISABLE:
		perf_counter_disable_family(counter);
		break;
		case PERF_COUNTER_IOC_REFRESH:
		perf_counter_refresh(counter, arg);
		break;
		default:
		err = -ENOTTY;
		}
		@@ -1590,14 +1599,6 @@ void perf_counter_wakeup(struct perf_counter *counter)
		kill_fasync(&counter->fasync, SIGIO, POLL_IN);
		}

		static void perf_pending_wakeup(struct perf_pending_entry *entry)
		{
		struct perf_counter *counter = container_of(entry,
		struct perf_counter, pending);

		perf_counter_wakeup(counter);
		}

		/*
		* Pending wakeups
		*
		@@ -1607,6 +1608,22 @@ static void perf_pending_wakeup(struct perf_pending_entry *entry)
		* single linked list and use cmpxchg() to add entries lockless.
		*/

		static void perf_pending_counter(struct perf_pending_entry *entry)
		{
		struct perf_counter *counter = container_of(entry,
		struct perf_counter, pending);

		if (counter->pending_disable) {
		counter->pending_disable = 0;
		perf_counter_disable(counter);
		}

		if (counter->pending_wakeup) {
		counter->pending_wakeup = 0;
		perf_counter_wakeup(counter);
		}
		}

		#define PENDING_TAIL ((struct perf_pending_entry *)-1UL)

		static DEFINE_PER_CPU(struct perf_pending_entry *, perf_pending_head) = {
		@@ -1715,8 +1732,9 @@ struct perf_output_handle {
		static inline void __perf_output_wakeup(struct perf_output_handle *handle)
		{
		if (handle->nmi) {
		handle->counter->pending_wakeup = 1;
		perf_pending_queue(&handle->counter->pending,
		perf_pending_wakeup);
		perf_pending_counter);
		} else
		perf_counter_wakeup(handle->counter);
		}
		@@ -2063,8 +2081,21 @@ void perf_counter_munmap(unsigned long addr, unsigned long len,
		int perf_counter_overflow(struct perf_counter *counter,
		int nmi, struct pt_regs *regs)
		{
		int events = atomic_read(&counter->event_limit);
		int ret = 0;

		if (events && atomic_dec_and_test(&counter->event_limit)) {
		ret = 1;
		if (nmi) {
		counter->pending_disable = 1;
		perf_pending_queue(&counter->pending,
		perf_pending_counter);
		} else
		perf_counter_disable(counter);
		}

		perf_counter_output(counter, nmi, regs);
		return 0;
		return ret;
		}

		/*

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