Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754508AbbKQRsr (ORCPT ); Tue, 17 Nov 2015 12:48:47 -0500 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:6556 "EHLO mail2-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754484AbbKQRso (ORCPT ); Tue, 17 Nov 2015 12:48:44 -0500 X-IronPort-AV: E=Sophos;i="5.20,308,1444687200"; d="scan'208";a="187946134" Date: Tue, 17 Nov 2015 18:48:39 +0100 (CET) From: Julia Lawall X-X-Sender: jll@hadrien To: Brian Norris cc: Julia Lawall , 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 In-Reply-To: <20151117174430.GA8456@google.com> Message-ID: 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> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) 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: 3376 Lines: 99 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: > > > > > > This reminds me of a potential problem I'm looking at in other > > > subsystems: from code reading (I haven't seen any issues in practice, > > > probably because I don't use OF_DYNAMIC) it looks like device-creating > > > infrastructure like the PHY subsystem should be acquiring a reference to > > > the device_node when they stash it away. But drivers/phy/phy-core.c does > > > not do this, AFAICT. > > > > > > See phy_create(), which does > > > > > > phy->dev.of_node = node ?: dev->of_node; > > > > > > and later might reuse this of_node pointer, even though it never called > > > of_node_get() on this node. > > > > > > Potential patch to fix this (not tested). > > > > > > Signed-off-by: Brian Norris > > > > > > 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? If it is not possible, then the ?: in the function argument is probably a bit ugly... Is this something that should be checked for elsewhere? julia > If my understanding is correct, I'll send a proper patch to do the > latter. > > Regards, > Brian > > > julia > > > > > phy->id = id; > > > phy->ops = ops; > > > > > > @@ -726,6 +727,7 @@ struct phy *phy_create(struct device *dev, struct device_node *node, > > > return phy; > > > > > > put_dev: > > > + of_node_put(phy->dev.of_node); > > > put_device(&phy->dev); /* calls phy_release() which frees resources */ > > > return ERR_PTR(ret); > > > > > > @@ -775,6 +777,7 @@ EXPORT_SYMBOL_GPL(devm_phy_create); > > > */ > > > void phy_destroy(struct phy *phy) > > > { > > > + of_node_put(phy->dev.of_node); > > > pm_runtime_disable(&phy->dev); > > > device_unregister(&phy->dev); > > > } > > > -- > > > To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in > > > the body of a message to majordomo@vger.kernel.org > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- 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/