From mboxrd@z Thu Jan 1 00:00:00 1970 From: DDD Subject: Re: [PATCH] netpoll: WARN_ONCE for start_xmit returns with interrupts enabled Date: Thu, 20 Aug 2009 18:44:00 +0800 Message-ID: <1250765040.17891.91.camel@dengdd-desktop> References: <1250678607.17891.26.camel@dengdd-desktop> <1250678596.3937.182.camel@calx> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, Ingo Molnar , David Miller , netdev@vger.kernel.org To: Matt Mackall Return-path: Received: from mail.windriver.com ([147.11.1.11]:53561 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753191AbZHTKbv (ORCPT ); Thu, 20 Aug 2009 06:31:51 -0400 In-Reply-To: <1250678596.3937.182.camel@calx> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2009-08-19 at 05:43 -0500, Matt Mackall wrote: > On Wed, 2009-08-19 at 18:43 +0800, DDD wrote: > > The NETPOLL API requires that interrupts remain disabled in > > netpoll_send_skb(). > > > > Add a WARN_ONCE when ndo_start_xmit returns with interrupts enabled > > in netpoll_send_skb(). > > > > Signed-off-by: Dongdong Deng > > --- > > net/core/netpoll.c | 6 ++++++ > > 1 files changed, 6 insertions(+), 0 deletions(-) > > > > diff --git a/net/core/netpoll.c b/net/core/netpoll.c > > index df30feb..d38103f 100644 > > --- a/net/core/netpoll.c > > +++ b/net/core/netpoll.c > > @@ -319,6 +319,12 @@ static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb) > > > > udelay(USEC_PER_POLL); > > } > > + > > + WARN_ONCE(!irqs_disabled(), > > + KERN_WARNING "netpoll_send_skb(): [net driver %s]" > > + "ndo_start_xmit() shouldn't return with interrupts" > > + "enabled!", dev->name); > > Hmm, perhaps: > > "netpoll_send_skb(): %s enabled interrupts in poll (%pF)\n", > dev->name, ops->ndo_start_xmit > > That'll give us a real function name and maybe even a module name. Thanks, I will modify it as your suggestions. When I test the WRAN_ONCE, I find that some net drivers still have this problem, such as using local_irq_disable/local_irq_enable in ndo_start_xmit() or other cases. I will do an new patch and hope it could fix this problem completely in all the net drivers that support NETPOLL. I check the drivers that support NETPOLL one by one again(almost 100 drivers), and following drivers's fix will be included by my patch: 1: ixp2000/ixpdev.c : 66 local_irq_disable 2: fec_mpc52xx.c : 319 spin_unlock_irq 3: macb.c:602 : 638 spin_unlock_irq 4: mlx4/en_netdev.c : 448 mlx4_en_xmit() -> mlx4_en_xmit_poll() -> spin_trylock_irq 5: smc91x.c It seems that there is a lots work to let smc91x work well with netpoll. Thanks, Dongdong >