Merge tag 'at24-4.16-updates-for-wolfram' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux into i2c/for-4.16

"AT24 updates for 4.16 merge window

The driver has been converted to using regmap instead of raw i2c and
smbus calls which shrank the code significantly.

Device tree binding document has been cleaned up. Device tree support in
the driver has been improved and we now support all at24 models as well
as two new DT properties (no-read-rollover and wp-gpios).

We no longer user unreadable magic values for driver data as the way it
was implemented caused problems for some EEPROM models - we switched to
regular structs.

Aside from that, there's a bunch of coding style fixes and minor
improvements all over the place."

1 files changed, 11 insertions, 7 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 91874a95060d..9ab18995ff1e 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -280,6 +280,8 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data);
 /* Missed count stored at end */
 #define RB_MISSED_STORED	(1 << 30)
 
+#define RB_MISSED_FLAGS		(RB_MISSED_EVENTS|RB_MISSED_STORED)
+
 struct buffer_data_page {
 	u64		 time_stamp;	/* page time stamp */
 	local_t		 commit;	/* write committed index */
@@ -331,7 +333,9 @@ static void rb_init_page(struct buffer_data_page *bpage)
  */
 size_t ring_buffer_page_len(void *page)
 {
-	return local_read(&((struct buffer_data_page *)page)->commit)
+	struct buffer_data_page *bpage = page;
+
+	return (local_read(&bpage->commit) & ~RB_MISSED_FLAGS)
 		+ BUF_PAGE_HDR_SIZE;
 }
 
@@ -1799,12 +1803,6 @@ void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val)
 }
 EXPORT_SYMBOL_GPL(ring_buffer_change_overwrite);
 
-static __always_inline void *
-__rb_data_page_index(struct buffer_data_page *bpage, unsigned index)
-{
-	return bpage->data + index;
-}
-
 static __always_inline void *__rb_page_index(struct buffer_page *bpage, unsigned index)
 {
 	return bpage->page->data + index;
@@ -4406,8 +4404,13 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data)
 {
 	struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
 	struct buffer_data_page *bpage = data;
+	struct page *page = virt_to_page(bpage);
 	unsigned long flags;
 
+	/* If the page is still in use someplace else, we can't reuse it */
+	if (page_ref_count(page) > 1)
+		goto out;
+
 	local_irq_save(flags);
 	arch_spin_lock(&cpu_buffer->lock);
 
@@ -4419,6 +4422,7 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data)
 	arch_spin_unlock(&cpu_buffer->lock);
 	local_irq_restore(flags);
 
+ out:
 	free_page((unsigned long)bpage);
 }
 EXPORT_SYMBOL_GPL(ring_buffer_free_read_page);