From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755090Ab0HMT7R (ORCPT ); Fri, 13 Aug 2010 15:59:17 -0400 Received: from trinity.develer.com ([83.149.158.210]:60555 "EHLO trinity.develer.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753603Ab0HMT7N (ORCPT ); Fri, 13 Aug 2010 15:59:13 -0400 From: Andrea Righi To: Stefani Seibold Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: [PATCH 1/3] kfifo: fix kernel BUG in dma example Date: Fri, 13 Aug 2010 21:59:03 +0200 Message-Id: <1281729545-1663-1-git-send-email-arighi@develer.com> X-Mailer: git-send-email 1.7.0.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The scatterlist is used uninitialized in kfifo_dma_in_prepare(). This triggers the following bug if CONFIG_DEBUG_SG=y: ------------[ cut here ]------------ kernel BUG at include/linux/scatterlist.h:65! invalid opcode: 0000 [#1] PREEMPT SMP ... Call Trace: [] setup_sgl+0x6b/0xe0 [] ? example_init+0x0/0x265 [dma_example] [] __kfifo_dma_in_prepare+0x21/0x30 [] example_init+0x124/0x265 [dma_example] [] ? trace_module_notify+0x25/0x370 [] ? free_pages_prepare+0x11e/0x1e0 [] ? get_parent_ip+0x11/0x50 [] ? trace_module_notify+0x25/0x370 [] ? trace_hardirqs_on+0xd/0x10 [] ? mutex_unlock+0xe/0x10 [] ? trace_module_notify+0x41/0x370 [] ? __blocking_notifier_call_chain+0x45/0x80 [] ? vfree+0x2a/0x30 [] ? up_read+0x23/0x40 [] ? __blocking_notifier_call_chain+0x65/0x80 [] do_one_initcall+0x43/0x180 [] sys_init_module+0xba/0x200 [] system_call_fastpath+0x16/0x1b RIP [] setup_sgl_buf+0x1a1/0x1b0 RSP ---[ end trace a72b979fd3c1d3a5 ]--- Add the proper initialization to avoid the bug. Signed-off-by: Andrea Righi --- samples/kfifo/dma-example.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c index b9482c2..03433ca 100644 --- a/samples/kfifo/dma-example.c +++ b/samples/kfifo/dma-example.c @@ -45,6 +45,7 @@ static int __init example_init(void) printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo)); + sg_init_table(sg, ARRAY_SIZE(sg)); ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE); printk(KERN_INFO "DMA sgl entries: %d\n", ret); -- 1.7.0.4