perf_counter: generalize pending infrastructure (671dec5d) · Commits · 戴 / test

include/linux/perf_counter.h

+4 −3

Original line number	Diff line number	Diff line
		@@ -321,8 +321,9 @@ struct perf_mmap_data {
		void *data_pages[0];
		};

		struct perf_wakeup_entry {
		struct perf_wakeup_entry *next;
		struct perf_pending_entry {
		struct perf_pending_entry *next;
		void (func)(struct perf_pending_entry );
		};

		/**
		@@ -401,7 +402,7 @@ struct perf_counter {
		wait_queue_head_t waitq;
		struct fasync_struct *fasync;
		/* optional: for NMIs */
		struct perf_wakeup_entry wakeup;
		struct perf_pending_entry pending;

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

kernel/perf_counter.c

+32 −21

Original line number	Diff line number	Diff line
		@@ -1581,6 +1581,14 @@ 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
		*
		@@ -1590,45 +1598,47 @@ void perf_counter_wakeup(struct perf_counter *counter)
		* single linked list and use cmpxchg() to add entries lockless.
		*/

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

		static DEFINE_PER_CPU(struct perf_wakeup_entry *, perf_wakeup_head) = {
		static DEFINE_PER_CPU(struct perf_pending_entry *, perf_pending_head) = {
		PENDING_TAIL,
		};

		static void perf_pending_queue(struct perf_counter *counter)
		static void perf_pending_queue(struct perf_pending_entry *entry,
		void (func)(struct perf_pending_entry ))
		{
		struct perf_wakeup_entry **head;
		struct perf_wakeup_entry prev, next;
		struct perf_pending_entry **head;

		if (cmpxchg(&counter->wakeup.next, NULL, PENDING_TAIL) != NULL)
		if (cmpxchg(&entry->next, NULL, PENDING_TAIL) != NULL)
		return;

		head = &get_cpu_var(perf_wakeup_head);
		entry->func = func;

		head = &get_cpu_var(perf_pending_head);

		do {
		prev = counter->wakeup.next = *head;
		next = &counter->wakeup;
		} while (cmpxchg(head, prev, next) != prev);
		entry->next = *head;
		} while (cmpxchg(head, entry->next, entry) != entry->next);

		set_perf_counter_pending();

		put_cpu_var(perf_wakeup_head);
		put_cpu_var(perf_pending_head);
		}

		static int __perf_pending_run(void)
		{
		struct perf_wakeup_entry *list;
		struct perf_pending_entry *list;
		int nr = 0;

		list = xchg(&__get_cpu_var(perf_wakeup_head), PENDING_TAIL);
		list = xchg(&__get_cpu_var(perf_pending_head), PENDING_TAIL);
		while (list != PENDING_TAIL) {
		struct perf_counter *counter = container_of(list,
		struct perf_counter, wakeup);
		void (func)(struct perf_pending_entry );
		struct perf_pending_entry *entry = list;

		list = list->next;

		counter->wakeup.next = NULL;
		func = entry->func;
		entry->next = NULL;
		/*
		* Ensure we observe the unqueue before we issue the wakeup,
		* so that we won't be waiting forever.
		@@ -1636,7 +1646,7 @@ static int __perf_pending_run(void)
		*/
		smp_wmb();

		perf_counter_wakeup(counter);
		func(entry);
		nr++;
		}

		@@ -1658,7 +1668,7 @@ static inline int perf_not_pending(struct perf_counter *counter)
		* so that we do not miss the wakeup. -- see perf_pending_handle()
		*/
		smp_rmb();
		return counter->wakeup.next == NULL;
		return counter->pending.next == NULL;
		}

		static void perf_pending_sync(struct perf_counter *counter)
		@@ -1695,9 +1705,10 @@ struct perf_output_handle {

		static inline void __perf_output_wakeup(struct perf_output_handle *handle)
		{
		if (handle->nmi)
		perf_pending_queue(handle->counter);
		else
		if (handle->nmi) {
		perf_pending_queue(&handle->counter->pending,
		perf_pending_wakeup);
		} else
		perf_counter_wakeup(handle->counter);
		}

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