From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1Ez1Ao-0007KW-Kz for user-mode-linux-devel@lists.sourceforge.net; Tue, 17 Jan 2006 16:27:38 -0800 Received: from [151.97.230.9] (helo=ssc.unict.it) by mail.sourceforge.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.44) id 1Ez1Ao-0005Bz-3z for user-mode-linux-devel@lists.sourceforge.net; Tue, 17 Jan 2006 16:27:38 -0800 From: "Paolo 'Blaisorblade' Giarrusso" Message-Id: <20060118001931.14622.17211.stgit@zion.home.lan> In-Reply-To: <20060117235659.14622.18544.stgit@zion.home.lan> References: <20060117235659.14622.18544.stgit@zion.home.lan> Subject: [uml-devel] [PATCH 4/9] uml: fix spinlock recursion and sleep-inside-spinlock in error path Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Wed, 18 Jan 2006 01:19:33 +0100 To: Andrew Morton Cc: Jeff Dike , linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net From: Paolo 'Blaisorblade' Giarrusso In this error path, when the interface has had a problem, we call dev_close(), which is disallowed for two reasons: *) takes again the UML internal spinlock, inside the ->stop method of this device *) can be called in process context only, while we're in interrupt context. I've also thought that calling dev_close() may be a wrong policy to follow, but it's not up to me to decide that. However, we may end up with multiple dev_close() queued on the same device. But the initial test for (dev->flags & IFF_UP) makes this harmless, though - and dev_close() is supposed to care about races with itself. So there's no harm in delaying the shutdown, IMHO. Something to mark the interface as "going to shutdown" would be appreciated, but dev_deactivate has the same problems as dev_close(), so we can't use it either. Signed-off-by: Paolo 'Blaisorblade' Giarrusso --- arch/um/drivers/net_kern.c | 15 +++++++++++++-- 1 files changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c index 98350bb..178f68b 100644 --- a/arch/um/drivers/net_kern.c +++ b/arch/um/drivers/net_kern.c @@ -68,6 +68,11 @@ static int uml_net_rx(struct net_device return pkt_len; } +static void uml_dev_close(void* dev) +{ + dev_close( (struct net_device *) dev); +} + irqreturn_t uml_net_interrupt(int irq, void *dev_id, struct pt_regs *regs) { struct net_device *dev = dev_id; @@ -80,15 +85,21 @@ irqreturn_t uml_net_interrupt(int irq, v spin_lock(&lp->lock); while((err = uml_net_rx(dev)) > 0) ; if(err < 0) { + DECLARE_WORK(close_work, uml_dev_close, dev); printk(KERN_ERR "Device '%s' read returned %d, shutting it down\n", dev->name, err); - dev_close(dev); + /* dev_close can't be called in interrupt context, and takes + * again lp->lock. + * And dev_close() can be safely called multiple times on the + * same device, since it tests for (dev->flags & IFF_UP). So + * there's no harm in delaying the device shutdown. */ + schedule_work(&close_work); goto out; } reactivate_fd(lp->fd, UM_ETH_IRQ); - out: +out: spin_unlock(&lp->lock); return(IRQ_HANDLED); } ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=103432&bid=230486&dat=121642 _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel