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-rw-r--r--kernel/trace/ring_buffer.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index faf56d9a9e..943850b25f 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1456,6 +1456,11 @@ static void rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer,
*
* As a safety measure we check to make sure the data pages have not
* been corrupted.
+ *
+ * Callers of this function need to guarantee that the list of pages doesn't get
+ * modified during the check. In particular, if it's possible that the function
+ * is invoked with concurrent readers which can swap in a new reader page then
+ * the caller should take cpu_buffer->reader_lock.
*/
static void rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer)
{
@@ -2205,8 +2210,12 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size,
*/
synchronize_rcu();
for_each_buffer_cpu(buffer, cpu) {
+ unsigned long flags;
+
cpu_buffer = buffer->buffers[cpu];
+ raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
rb_check_pages(cpu_buffer);
+ raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
}
atomic_dec(&buffer->record_disabled);
}