Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932289AbbKQSan (ORCPT ); Tue, 17 Nov 2015 13:30:43 -0500 Received: from mail-pa0-f46.google.com ([209.85.220.46]:35807 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932248AbbKQSaj (ORCPT ); Tue, 17 Nov 2015 13:30:39 -0500 Date: Tue, 17 Nov 2015 10:30:36 -0800 From: Brian Norris To: Julia Lawall Cc: Kishon Vijay Abraham I , kernel-janitors@vger.kernel.org, Gregory Fong , Florian Fainelli , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Russell King - ARM Linux , Thomas Petazzoni , Andrew Lunn , Bjorn Helgaas , Jason Cooper Subject: Re: [PATCH 1/7] phy: brcmstb-sata: add missing of_node_put Message-ID: <20151117183036.GF8456@google.com> References: <1447673600-8881-1-git-send-email-Julia.Lawall@lip6.fr> <1447673600-8881-2-git-send-email-Julia.Lawall@lip6.fr> <20151117013830.GV8456@google.com> <20151117174430.GA8456@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2398 Lines: 60 On Tue, Nov 17, 2015 at 06:48:39PM +0100, Julia Lawall wrote: > On Tue, 17 Nov 2015, Brian Norris wrote: > > On Tue, Nov 17, 2015 at 07:12:22AM +0100, Julia Lawall wrote: > > > On Mon, 16 Nov 2015, Brian Norris wrote: > > > > diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c > > > > index fc48fac003a6..8df29caeeef9 100644 > > > > --- a/drivers/phy/phy-core.c > > > > +++ b/drivers/phy/phy-core.c > > > > @@ -697,6 +697,7 @@ struct phy *phy_create(struct device *dev, struct device_node *node, > > > > phy->dev.class = phy_class; > > > > phy->dev.parent = dev; > > > > phy->dev.of_node = node ?: dev->of_node; > > > > + of_node_get(phy->dev.of_node); > > > > > > Why not put of_node_get around dev->of_node? > > > > Like this? > > > > phy->dev.of_node = node ?: of_node_get(dev->of_node); > > > > Or this? > > > > phy->dev.of_node = of_node_get(node ?: dev->of_node); > > > > The former wouldn't do what I proposed; if this PHY device is created > > with a sub-node of 'dev' rather than dev->of_node, then the caller will > > pass it in as the 2nd argument to phy_create (i.e., 'node'), and then I > > expect it's the PHY core's responsibility to refcount it. > > > > I'd be fine with the latter. Looks a little better, I suppose. > > I proposed it because I was worried that the of_node field could end up > containing something that had been freed. But probably this is not > possible? AIUI, the caller of phy_create() should already have a refcount on both 'dev->of_node' and 'node' (if applicable), so nobody should be freeing it from underneath us right here. But *after* phy_create() returns, there's no guarantee the caller will hold a reference for us. So even if it's ever possible, I'd consider it a bug in the caller, not in phy_create(). > If it is not possible, then the ?: in the function argument is > probably a bit ugly... OK, then I'll go with my first proposal. > Is this something that should be checked for elsewhere? I expect the same sort of problem shows up plenty of other places. I don't think many people use CONFIG_OF_DYNAMIC, so the effects of these failures probably aren't felt by many. Brian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/