tracing: allocate page when needed
Impact: Cleanup
Sometimes, we open trace_pipe_raw, but we don't read(2) it,
we just splice(2) it, thus, the page is not used.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D4666B.4010608@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 24b0168..8e189ff 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3277,19 +3277,13 @@
info->tr = &global_trace;
info->cpu = cpu;
- info->spare = ring_buffer_alloc_read_page(info->tr->buffer);
+ info->spare = NULL;
/* Force reading ring buffer for first read */
info->read = (unsigned int)-1;
- if (!info->spare)
- goto out;
filp->private_data = info;
return nonseekable_open(inode, filp);
-
- out:
- kfree(info);
- return -ENOMEM;
}
static ssize_t
@@ -3304,6 +3298,11 @@
if (!count)
return 0;
+ if (!info->spare)
+ info->spare = ring_buffer_alloc_read_page(info->tr->buffer);
+ if (!info->spare)
+ return -ENOMEM;
+
/* Do we have previous read data to read? */
if (info->read < PAGE_SIZE)
goto read;
@@ -3342,7 +3341,8 @@
{
struct ftrace_buffer_info *info = file->private_data;
- ring_buffer_free_read_page(info->tr->buffer, info->spare);
+ if (info->spare)
+ ring_buffer_free_read_page(info->tr->buffer, info->spare);
kfree(info);
return 0;
