From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751425AbaKFV0n (ORCPT ); Thu, 6 Nov 2014 16:26:43 -0500 Received: from mail-lb0-f177.google.com ([209.85.217.177]:35277 "EHLO mail-lb0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751302AbaKFV0l (ORCPT ); Thu, 6 Nov 2014 16:26:41 -0500 From: Rabin Vincent To: Steven Rostedt , Ingo Molnar Cc: linux-kernel@vger.kernel.org, Rabin Vincent Subject: [PATCH 2/2] tracing: don't risk busy looping in buffer splice Date: Thu, 6 Nov 2014 22:26:07 +0100 Message-Id: <1415309167-2373-2-git-send-email-rabin@rab.in> X-Mailer: git-send-email 2.1.1 In-Reply-To: <1415309167-2373-1-git-send-email-rabin@rab.in> References: <1415309167-2373-1-git-send-email-rabin@rab.in> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Signed-off-by: Rabin Vincent --- 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 e67d0de..e838c96 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5501,7 +5501,7 @@ 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); @@ -5539,13 +5539,16 @@ 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; } @@ -5583,6 +5586,9 @@ 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; -- 2.1.1