Merge tag 'kbuild-fixes-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masah...

[linux-2.6-microblaze.git] / kernel / trace / ring_buffer.c

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index c87766c..9ab1899 100644 (file)
--- 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;
 }
 
@@ -4400,8 +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);
 
@@ -4413,6 +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);