From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 28 May 2010 08:24:03 +0000 (+0200)
Subject: Merge branch 'tip/perf/core' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt... 
X-Git-Tag: v2.6.35-rc1~3^2
X-Git-Url: http://ftp.safe.ca/?a=commitdiff_plain;h=92af1abde4f2d74c9e5f7b670a1971779ed0b051;hp=c4fe52a8ee730ed340eba8fe6ccbf26347ebe9aa;p=safe%2Fjmp%2Flinux-2.6

Merge branch 'tip/perf/core' of git://git./linux/kernel/git/rostedt/linux-2.6-trace into perf/urgent
---

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 7f6059c..1da7b6e 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);
 
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ba0ec81..95d0b1a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3661,7 +3661,6 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 		     size_t count, loff_t *ppos)
 {
 	struct ftrace_buffer_info *info = filp->private_data;
-	unsigned int pos;
 	ssize_t ret;
 	size_t size;
 
@@ -3688,11 +3687,6 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 	if (ret < 0)
 		return 0;
 
-	pos = ring_buffer_page_len(info->spare);
-
-	if (pos < PAGE_SIZE)
-		memset(info->spare + pos, 0, PAGE_SIZE - pos);
-
 read:
 	size = PAGE_SIZE - info->read;
 	if (size > count)