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-rw-r--r--kernel/trace/ring_buffer.c19
1 files changed, 17 insertions, 2 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 7f6059c5aa9..1da7b6ea8b8 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1768,6 +1768,14 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer,
* must fill the old tail_page with padding.
*/
if (tail >= BUF_PAGE_SIZE) {
+ /*
+ * If the page was filled, then we still need
+ * to update the real_end. Reset it to zero
+ * and the reader will ignore it.
+ */
+ if (tail == BUF_PAGE_SIZE)
+ tail_page->real_end = 0;
+
local_sub(length, &tail_page->write);
return;
}
@@ -3894,12 +3902,12 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
ret = read;
cpu_buffer->lost_events = 0;
+
+ commit = local_read(&bpage->commit);
/*
* Set a flag in the commit field if we lost events
*/
if (missed_events) {
- commit = local_read(&bpage->commit);
-
/* If there is room at the end of the page to save the
* missed events, then record it there.
*/
@@ -3907,10 +3915,17 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
memcpy(&bpage->data[commit], &missed_events,
sizeof(missed_events));
local_add(RB_MISSED_STORED, &bpage->commit);
+ commit += sizeof(missed_events);
}
local_add(RB_MISSED_EVENTS, &bpage->commit);
}
+ /*
+ * This page may be off to user land. Zero it out here.
+ */
+ if (commit < BUF_PAGE_SIZE)
+ memset(&bpage->data[commit], 0, BUF_PAGE_SIZE - commit);
+
out_unlock:
spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);