From 07906da78810dce5fd35b9449358c9208c693dca Mon Sep 17 00:00:00 2001
From: Rabin Vincent <rabin@rab.in>
Date: Thu, 6 Nov 2014 22:26:07 +0100
Subject: [PATCH] tracing: Do not risk busy looping in buffer splice
If the read loop in trace_buffers_splice_read() keeps failing due to
memory allocation failures without reading even a single page then this
function will keep busy looping.
Remove the risk for that by exiting the function if memory allocation
failures are seen.
Link: http://lkml.kernel.org/r/1415309167-2373-2-git-send-email-rabin@rab.in
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 15209335888db..92f4a6cee1727 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5494,7 +5494,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
};
struct buffer_ref *ref;
int entries, size, i;
- ssize_t ret;
+ ssize_t ret = 0;
mutex_lock(&trace_types_lock);
@@ -5532,13 +5532,16 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
int r;
ref = kzalloc(sizeof(*ref), GFP_KERNEL);
- if (!ref)
+ if (!ref) {
+ ret = -ENOMEM;
break;
+ }
ref->ref = 1;
ref->buffer = iter->trace_buffer->buffer;
ref->page = ring_buffer_alloc_read_page(ref->buffer, iter->cpu_file);
if (!ref->page) {
+ ret = -ENOMEM;
kfree(ref);
break;
}
@@ -5576,6 +5579,9 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
/* did we read anything? */
if (!spd.nr_pages) {
+ if (ret)
+ goto out;
+
if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK)) {
ret = -EAGAIN;
goto out;
--
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