Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751965AbdLLDiz (ORCPT ); Mon, 11 Dec 2017 22:38:55 -0500 Received: from kvm5.telegraphics.com.au ([98.124.60.144]:52880 "EHLO kvm5.telegraphics.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751379AbdLLDiy (ORCPT ); Mon, 11 Dec 2017 22:38:54 -0500 Date: Tue, 12 Dec 2017 14:38:57 +1100 (AEDT) From: Finn Thain To: Jia-Ju Bai cc: schmitzmic@gmail.com, jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Jia-Ju Bai Subject: Re: [PATCH] NCR5380: Fix a possible sleep-in-atomic bug in NCR5380_poll_politely2 In-Reply-To: <1513047037-18102-1-git-send-email-baijiaju1990@163.com> Message-ID: References: <1513047037-18102-1-git-send-email-baijiaju1990@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1759 Lines: 64 On Tue, 12 Dec 2017, Jia-Ju Bai wrote: > From: Jia-Ju Bai > > The kernel module may sleep under a spinlock. The spinlock is always taken in irq mode, and the schedule_timeout_uninterruptible() is conditional on !irqs_disabled(). > The function call paths are: > NCR5380_select (acquire the spinlock) > NCR5380_reselect > NCR5380_poll_politely > NCR5380_poll_politely2 > schedule_timeout_uninterruptible --> may sleep > > NCR5380_abort (acquire the spinlock) > do_abort > NCR5380_poll_politely > NCR5380_poll_politely2 > schedule_timeout_uninterruptible --> may sleep > Well, it's expected to sleep here, hence the "sleep for 1ms" comment. (I notice that you left the comment unchanged in your "fix", was that an oversight?) > To fix it, schedule_timeout_uninterruptible is replaced with mdelay. > > This bug is found by my static analysis tool(DSAC) and checked by my > code review. > > > Signed-off-by: Jia-Ju Bai NAK. > --- > drivers/scsi/NCR5380.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c > index 90ea0f5..4176aca 100644 > --- a/drivers/scsi/NCR5380.c > +++ b/drivers/scsi/NCR5380.c > @@ -202,7 +202,7 @@ static int NCR5380_poll_politely2(struct NCR5380_hostdata *hostdata, > Here's a little more context: if (irqs_disabled() || in_interrupt()) return -ETIMEDOUT; > /* Repeatedly sleep for 1 ms until deadline */ > while (time_is_after_jiffies(deadline)) { > - schedule_timeout_uninterruptible(1); > + mdelay(1); > if ((NCR5380_read(reg1) & bit1) == val1) > return 0; > if ((NCR5380_read(reg2) & bit2) == val2) > --