1 files changed, 243 insertions, 68 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index e206951603c1..7f69cfeaadf7 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -195,20 +195,24 @@ void *ring_buffer_event_data(struct ring_buffer_event *event)
 #define TS_MASK		((1ULL << TS_SHIFT) - 1)
 #define TS_DELTA_TEST	(~TS_MASK)
 
-/*
- * This hack stolen from mm/slob.c.
- * We can store per page timing information in the page frame of the page.
- * Thanks to Peter Zijlstra for suggesting this idea.
- */
-struct buffer_page {
+struct buffer_data_page {
 	u64		 time_stamp;	/* page time stamp */
-	local_t		 write;		/* index for next write */
 	local_t		 commit;	/* write commited index */
+	unsigned char	 data[];	/* data of buffer page */
+};
+
+struct buffer_page {
+	local_t		 write;		/* index for next write */
 	unsigned	 read;		/* index for next read */
 	struct list_head list;		/* list of free pages */
-	void *page;			/* Actual data page */
+	struct buffer_data_page *page;	/* Actual data page */
 };
 
+static void rb_init_page(struct buffer_data_page *bpage)
+{
+	local_set(&bpage->commit, 0);
+}
+
 /*
  * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing
  * this issue out.
@@ -230,7 +234,7 @@ static inline int test_time_stamp(u64 delta)
 	return 0;
 }
 
-#define BUF_PAGE_SIZE PAGE_SIZE
+#define BUF_PAGE_SIZE (PAGE_SIZE - sizeof(struct buffer_data_page))
 
 /*
  * head_page == tail_page && head == tail then buffer is empty.
@@ -294,19 +298,19 @@ struct ring_buffer_iter {
 static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer)
 {
 	struct list_head *head = &cpu_buffer->pages;
-	struct buffer_page *page, *tmp;
+	struct buffer_page *bpage, *tmp;
 
 	if (RB_WARN_ON(cpu_buffer, head->next->prev != head))
 		return -1;
 	if (RB_WARN_ON(cpu_buffer, head->prev->next != head))
 		return -1;
 
-	list_for_each_entry_safe(page, tmp, head, list) {
+	list_for_each_entry_safe(bpage, tmp, head, list) {
 		if (RB_WARN_ON(cpu_buffer,
-			       page->list.next->prev != &page->list))
+			       bpage->list.next->prev != &bpage->list))
 			return -1;
 		if (RB_WARN_ON(cpu_buffer,
-			       page->list.prev->next != &page->list))
+			       bpage->list.prev->next != &bpage->list))
 			return -1;
 	}
 
@@ -317,22 +321,23 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
 			     unsigned nr_pages)
 {
 	struct list_head *head = &cpu_buffer->pages;
-	struct buffer_page *page, *tmp;
+	struct buffer_page *bpage, *tmp;
 	unsigned long addr;
 	LIST_HEAD(pages);
 	unsigned i;
 
 	for (i = 0; i < nr_pages; i++) {
-		page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()),
+		bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
 				    GFP_KERNEL, cpu_to_node(cpu_buffer->cpu));
-		if (!page)
+		if (!bpage)
 			goto free_pages;
-		list_add(&page->list, &pages);
+		list_add(&bpage->list, &pages);
 
 		addr = __get_free_page(GFP_KERNEL);
 		if (!addr)
 			goto free_pages;
-		page->page = (void *)addr;
+		bpage->page = (void *)addr;
+		rb_init_page(bpage->page);
 	}
 
 	list_splice(&pages, head);
@@ -342,9 +347,9 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
 	return 0;
 
  free_pages:
-	list_for_each_entry_safe(page, tmp, &pages, list) {
-		list_del_init(&page->list);
-		free_buffer_page(page);
+	list_for_each_entry_safe(bpage, tmp, &pages, list) {
+		list_del_init(&bpage->list);
+		free_buffer_page(bpage);
 	}
 	return -ENOMEM;
 }
@@ -353,7 +358,7 @@ static struct ring_buffer_per_cpu *
 rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
 {
 	struct ring_buffer_per_cpu *cpu_buffer;
-	struct buffer_page *page;
+	struct buffer_page *bpage;
 	unsigned long addr;
 	int ret;
 
@@ -368,16 +373,17 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
 	cpu_buffer->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
 	INIT_LIST_HEAD(&cpu_buffer->pages);
 
-	page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()),
+	bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
 			    GFP_KERNEL, cpu_to_node(cpu));
-	if (!page)
+	if (!bpage)
 		goto fail_free_buffer;
 
-	cpu_buffer->reader_page = page;
+	cpu_buffer->reader_page = bpage;
 	addr = __get_free_page(GFP_KERNEL);
 	if (!addr)
 		goto fail_free_reader;
-	page->page = (void *)addr;
+	bpage->page = (void *)addr;
+	rb_init_page(bpage->page);
 
 	INIT_LIST_HEAD(&cpu_buffer->reader_page->list);
 
@@ -402,14 +408,14 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
 static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
 {
 	struct list_head *head = &cpu_buffer->pages;
-	struct buffer_page *page, *tmp;
+	struct buffer_page *bpage, *tmp;
 
 	list_del_init(&cpu_buffer->reader_page->list);
 	free_buffer_page(cpu_buffer->reader_page);
 
-	list_for_each_entry_safe(page, tmp, head, list) {
-		list_del_init(&page->list);
-		free_buffer_page(page);
+	list_for_each_entry_safe(bpage, tmp, head, list) {
+		list_del_init(&bpage->list);
+		free_buffer_page(bpage);
 	}
 	kfree(cpu_buffer);
 }
@@ -506,7 +512,7 @@ static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer);
 static void
 rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages)
 {
-	struct buffer_page *page;
+	struct buffer_page *bpage;
 	struct list_head *p;
 	unsigned i;
 
@@ -517,9 +523,9 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages)
 		if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages)))
 			return;
 		p = cpu_buffer->pages.next;
-		page = list_entry(p, struct buffer_page, list);
-		list_del_init(&page->list);
-		free_buffer_page(page);
+		bpage = list_entry(p, struct buffer_page, list);
+		list_del_init(&bpage->list);
+		free_buffer_page(bpage);
 	}
 	if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages)))
 		return;
@@ -536,7 +542,7 @@ static void
 rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer,
 		struct list_head *pages, unsigned nr_pages)
 {
-	struct buffer_page *page;
+	struct buffer_page *bpage;
 	struct list_head *p;
 	unsigned i;
 
@@ -547,9 +553,9 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer,
 		if (RB_WARN_ON(cpu_buffer, list_empty(pages)))
 			return;
 		p = pages->next;
-		page = list_entry(p, struct buffer_page, list);
-		list_del_init(&page->list);
-		list_add_tail(&page->list, &cpu_buffer->pages);
+		bpage = list_entry(p, struct buffer_page, list);
+		list_del_init(&bpage->list);
+		list_add_tail(&bpage->list, &cpu_buffer->pages);
 	}
 	rb_reset_cpu(cpu_buffer);
 
@@ -576,7 +582,7 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
 {
 	struct ring_buffer_per_cpu *cpu_buffer;
 	unsigned nr_pages, rm_pages, new_pages;
-	struct buffer_page *page, *tmp;
+	struct buffer_page *bpage, *tmp;
 	unsigned long buffer_size;
 	unsigned long addr;
 	LIST_HEAD(pages);
@@ -637,16 +643,17 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
 
 	for_each_buffer_cpu(buffer, cpu) {
 		for (i = 0; i < new_pages; i++) {
-			page = kzalloc_node(ALIGN(sizeof(*page),
+			bpage = kzalloc_node(ALIGN(sizeof(*bpage),
 						  cache_line_size()),
 					    GFP_KERNEL, cpu_to_node(cpu));
-			if (!page)
+			if (!bpage)
 				goto free_pages;
-			list_add(&page->list, &pages);
+			list_add(&bpage->list, &pages);
 			addr = __get_free_page(GFP_KERNEL);
 			if (!addr)
 				goto free_pages;
-			page->page = (void *)addr;
+			bpage->page = (void *)addr;
+			rb_init_page(bpage->page);
 		}
 	}
 
@@ -667,9 +674,9 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
 	return size;
 
  free_pages:
-	list_for_each_entry_safe(page, tmp, &pages, list) {
-		list_del_init(&page->list);
-		free_buffer_page(page);
+	list_for_each_entry_safe(bpage, tmp, &pages, list) {
+		list_del_init(&bpage->list);
+		free_buffer_page(bpage);
 	}
 	mutex_unlock(&buffer->mutex);
 	return -ENOMEM;
@@ -680,9 +687,15 @@ static inline int rb_null_event(struct ring_buffer_event *event)
 	return event->type == RINGBUF_TYPE_PADDING;
 }
 
-static inline void *__rb_page_index(struct buffer_page *page, unsigned index)
+static inline void *
+__rb_data_page_index(struct buffer_data_page *bpage, unsigned index)
 {
-	return page->page + index;
+	return bpage->data + index;
+}
+
+static inline void *__rb_page_index(struct buffer_page *bpage, unsigned index)
+{
+	return bpage->page->data + index;
 }
 
 static inline struct ring_buffer_event *
@@ -712,7 +725,7 @@ static inline unsigned rb_page_write(struct buffer_page *bpage)
 
 static inline unsigned rb_page_commit(struct buffer_page *bpage)
 {
-	return local_read(&bpage->commit);
+	return local_read(&bpage->page->commit);
 }
 
 /* Size is determined by what has been commited */
@@ -758,14 +771,14 @@ static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer)
 }
 
 static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer,
-			       struct buffer_page **page)
+			       struct buffer_page **bpage)
 {
-	struct list_head *p = (*page)->list.next;
+	struct list_head *p = (*bpage)->list.next;
 
 	if (p == &cpu_buffer->pages)
 		p = p->next;
 
-	*page = list_entry(p, struct buffer_page, list);
+	*bpage = list_entry(p, struct buffer_page, list);
 }
 
 static inline unsigned
@@ -804,14 +817,15 @@ rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer,
 		if (RB_WARN_ON(cpu_buffer,
 			  cpu_buffer->commit_page == cpu_buffer->tail_page))
 			return;
-		cpu_buffer->commit_page->commit =
+		cpu_buffer->commit_page->page->commit =
 			cpu_buffer->commit_page->write;
 		rb_inc_page(cpu_buffer, &cpu_buffer->commit_page);
-		cpu_buffer->write_stamp = cpu_buffer->commit_page->time_stamp;
+		cpu_buffer->write_stamp =
+			cpu_buffer->commit_page->page->time_stamp;
 	}
 
 	/* Now set the commit to the event's index */
-	local_set(&cpu_buffer->commit_page->commit, index);
+	local_set(&cpu_buffer->commit_page->page->commit, index);
 }
 
 static inline void
@@ -826,16 +840,17 @@ rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer)
 	 * assign the commit to the tail.
 	 */
 	while (cpu_buffer->commit_page != cpu_buffer->tail_page) {
-		cpu_buffer->commit_page->commit =
+		cpu_buffer->commit_page->page->commit =
 			cpu_buffer->commit_page->write;
 		rb_inc_page(cpu_buffer, &cpu_buffer->commit_page);
-		cpu_buffer->write_stamp = cpu_buffer->commit_page->time_stamp;
+		cpu_buffer->write_stamp =
+			cpu_buffer->commit_page->page->time_stamp;
 		/* add barrier to keep gcc from optimizing too much */
 		barrier();
 	}
 	while (rb_commit_index(cpu_buffer) !=
 	       rb_page_write(cpu_buffer->commit_page)) {
-		cpu_buffer->commit_page->commit =
+		cpu_buffer->commit_page->page->commit =
 			cpu_buffer->commit_page->write;
 		barrier();
 	}
@@ -843,7 +858,7 @@ rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer)
 
 static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
 {
-	cpu_buffer->read_stamp = cpu_buffer->reader_page->time_stamp;
+	cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp;
 	cpu_buffer->reader_page->read = 0;
 }
 
@@ -862,7 +877,7 @@ static inline void rb_inc_iter(struct ring_buffer_iter *iter)
 	else
 		rb_inc_page(cpu_buffer, &iter->head_page);
 
-	iter->read_stamp = iter->head_page->time_stamp;
+	iter->read_stamp = iter->head_page->page->time_stamp;
 	iter->head = 0;
 }
 
@@ -998,12 +1013,12 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 		 */
 		if (tail_page == cpu_buffer->tail_page) {
 			local_set(&next_page->write, 0);
-			local_set(&next_page->commit, 0);
+			local_set(&next_page->page->commit, 0);
 			cpu_buffer->tail_page = next_page;
 
 			/* reread the time stamp */
 			*ts = ring_buffer_time_stamp(cpu_buffer->cpu);
-			cpu_buffer->tail_page->time_stamp = *ts;
+			cpu_buffer->tail_page->page->time_stamp = *ts;
 		}
 
 		/*
@@ -1048,7 +1063,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 	 * this page's time stamp.
 	 */
 	if (!tail && rb_is_commit(cpu_buffer, event))
-		cpu_buffer->commit_page->time_stamp = *ts;
+		cpu_buffer->commit_page->page->time_stamp = *ts;
 
 	return event;
 
@@ -1099,7 +1114,7 @@ rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer,
 			event->time_delta = *delta & TS_MASK;
 			event->array[0] = *delta >> TS_SHIFT;
 		} else {
-			cpu_buffer->commit_page->time_stamp = *ts;
+			cpu_buffer->commit_page->page->time_stamp = *ts;
 			event->time_delta = 0;
 			event->array[0] = 0;
 		}
@@ -1552,7 +1567,7 @@ static void rb_iter_reset(struct ring_buffer_iter *iter)
 	if (iter->head)
 		iter->read_stamp = cpu_buffer->read_stamp;
 	else
-		iter->read_stamp = iter->head_page->time_stamp;
+		iter->read_stamp = iter->head_page->page->time_stamp;
 }
 
 /**
@@ -1696,7 +1711,7 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
 	cpu_buffer->reader_page->list.prev = reader->list.prev;
 
 	local_set(&cpu_buffer->reader_page->write, 0);
-	local_set(&cpu_buffer->reader_page->commit, 0);
+	local_set(&cpu_buffer->reader_page->page->commit, 0);
 
 	/* Make the reader page now replace the head */
 	reader->list.prev->next = &cpu_buffer->reader_page->list;
@@ -2088,7 +2103,7 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
 	cpu_buffer->head_page
 		= list_entry(cpu_buffer->pages.next, struct buffer_page, list);
 	local_set(&cpu_buffer->head_page->write, 0);
-	local_set(&cpu_buffer->head_page->commit, 0);
+	local_set(&cpu_buffer->head_page->page->commit, 0);
 
 	cpu_buffer->head_page->read = 0;
 
@@ -2097,7 +2112,7 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
 
 	INIT_LIST_HEAD(&cpu_buffer->reader_page->list);
 	local_set(&cpu_buffer->reader_page->write, 0);
-	local_set(&cpu_buffer->reader_page->commit, 0);
+	local_set(&cpu_buffer->reader_page->page->commit, 0);
 	cpu_buffer->reader_page->read = 0;
 
 	cpu_buffer->overrun = 0;
@@ -2223,6 +2238,166 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 	return 0;
 }
 
+static void rb_remove_entries(struct ring_buffer_per_cpu *cpu_buffer,
+			      struct buffer_data_page *bpage)
+{
+	struct ring_buffer_event *event;
+	unsigned long head;
+
+	__raw_spin_lock(&cpu_buffer->lock);
+	for (head = 0; head < local_read(&bpage->commit);
+	     head += rb_event_length(event)) {
+
+		event = __rb_data_page_index(bpage, head);
+		if (RB_WARN_ON(cpu_buffer, rb_null_event(event)))
+			return;
+		/* Only count data entries */
+		if (event->type != RINGBUF_TYPE_DATA)
+			continue;
+		cpu_buffer->entries--;
+	}
+	__raw_spin_unlock(&cpu_buffer->lock);
+}
+
+/**
+ * ring_buffer_alloc_read_page - allocate a page to read from buffer
+ * @buffer: the buffer to allocate for.
+ *
+ * This function is used in conjunction with ring_buffer_read_page.
+ * When reading a full page from the ring buffer, these functions
+ * can be used to speed up the process. The calling function should
+ * allocate a few pages first with this function. Then when it
+ * needs to get pages from the ring buffer, it passes the result
+ * of this function into ring_buffer_read_page, which will swap
+ * the page that was allocated, with the read page of the buffer.
+ *
+ * Returns:
+ *  The page allocated, or NULL on error.
+ */
+void *ring_buffer_alloc_read_page(struct ring_buffer *buffer)
+{
+	unsigned long addr;
+	struct buffer_data_page *bpage;
+
+	addr = __get_free_page(GFP_KERNEL);
+	if (!addr)
+		return NULL;
+
+	bpage = (void *)addr;
+
+	return bpage;
+}
+
+/**
+ * ring_buffer_free_read_page - free an allocated read page
+ * @buffer: the buffer the page was allocate for
+ * @data: the page to free
+ *
+ * Free a page allocated from ring_buffer_alloc_read_page.
+ */
+void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data)
+{
+	free_page((unsigned long)data);
+}
+
+/**
+ * ring_buffer_read_page - extract a page from the ring buffer
+ * @buffer: buffer to extract from
+ * @data_page: the page to use allocated from ring_buffer_alloc_read_page
+ * @cpu: the cpu of the buffer to extract
+ * @full: should the extraction only happen when the page is full.
+ *
+ * This function will pull out a page from the ring buffer and consume it.
+ * @data_page must be the address of the variable that was returned
+ * from ring_buffer_alloc_read_page. This is because the page might be used
+ * to swap with a page in the ring buffer.
+ *
+ * for example:
+ *	rpage = ring_buffer_alloc_page(buffer);
+ *	if (!rpage)
+ *		return error;
+ *	ret = ring_buffer_read_page(buffer, &rpage, cpu, 0);
+ *	if (ret)
+ *		process_page(rpage);
+ *
+ * When @full is set, the function will not return true unless
+ * the writer is off the reader page.
+ *
+ * Note: it is up to the calling functions to handle sleeps and wakeups.
+ *  The ring buffer can be used anywhere in the kernel and can not
+ *  blindly call wake_up. The layer that uses the ring buffer must be
+ *  responsible for that.
+ *
+ * Returns:
+ *  1 if data has been transferred
+ *  0 if no data has been transferred.
+ */
+int ring_buffer_read_page(struct ring_buffer *buffer,
+			    void **data_page, int cpu, int full)
+{
+	struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
+	struct ring_buffer_event *event;
+	struct buffer_data_page *bpage;
+	unsigned long flags;
+	int ret = 0;
+
+	if (!data_page)
+		return 0;
+
+	bpage = *data_page;
+	if (!bpage)
+		return 0;
+
+	spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+
+	/*
+	 * rb_buffer_peek will get the next ring buffer if
+	 * the current reader page is empty.
+	 */
+	event = rb_buffer_peek(buffer, cpu, NULL);
+	if (!event)
+		goto out;
+
+	/* check for data */
+	if (!local_read(&cpu_buffer->reader_page->page->commit))
+		goto out;
+	/*
+	 * If the writer is already off of the read page, then simply
+	 * switch the read page with the given page. Otherwise
+	 * we need to copy the data from the reader to the writer.
+	 */
+	if (cpu_buffer->reader_page == cpu_buffer->commit_page) {
+		unsigned int read = cpu_buffer->reader_page->read;
+
+		if (full)
+			goto out;
+		/* The writer is still on the reader page, we must copy */
+		bpage = cpu_buffer->reader_page->page;
+		memcpy(bpage->data,
+		       cpu_buffer->reader_page->page->data + read,
+		       local_read(&bpage->commit) - read);
+
+		/* consume what was read */
+		cpu_buffer->reader_page += read;
+
+	} else {
+		/* swap the pages */
+		rb_init_page(bpage);
+		bpage = cpu_buffer->reader_page->page;
+		cpu_buffer->reader_page->page = *data_page;
+		cpu_buffer->reader_page->read = 0;
+		*data_page = bpage;
+	}
+	ret = 1;
+
+	/* update the entry counter */
+	rb_remove_entries(cpu_buffer, bpage);
+ out:
+	spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+
+	return ret;
+}
+
 static ssize_t
 rb_simple_read(struct file *filp, char __user *ubuf,
 	       size_t cnt, loff_t *ppos)