Commit-ID: d47882078f05c2cb46b85f1e12a58ed9315b9d63
Gitweb: http://git.kernel.org/tip/d47882078f05c2cb46b85f1e12a58ed9315b9d63
Author: Steven Rostedt <srostedt@xxxxxxxxxx>
AuthorDate: Wed, 17 Jun 2009 00:39:43 -0400
Committer: Steven Rostedt <rostedt@xxxxxxxxxxx>
CommitDate: Wed, 17 Jun 2009 14:16:23 -0400
ring-buffer: add locks around rb_per_cpu_empty
The checking of whether the buffer is empty or not needs to be serialized
among the readers. Add the reader spin lock around it.
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
kernel/trace/ring_buffer.c | 11 +++++++++--
1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 2e99dba..969f7cb 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2756,12 +2756,17 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset);
int ring_buffer_empty(struct ring_buffer *buffer)
{
struct ring_buffer_per_cpu *cpu_buffer;
+ unsigned long flags;
int cpu;
+ int ret;
/* yes this is racy, but if you don't like the race, lock the buffer */
for_each_buffer_cpu(buffer, cpu) {
cpu_buffer = buffer->buffers[cpu];
- if (!rb_per_cpu_empty(cpu_buffer))
+ spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+ ret = rb_per_cpu_empty(cpu_buffer);
+ spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ if (!ret)
return 0;
}
@@ -2777,14 +2782,16 @@ EXPORT_SYMBOL_GPL(ring_buffer_empty);
int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
+ unsigned long flags;
int ret;
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return 1;
cpu_buffer = buffer->buffers[cpu];
+ spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
ret = rb_per_cpu_empty(cpu_buffer);
-
+ spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
return ret;
}
--
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