From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BD82F69799; Thu, 21 Dec 2023 10:54:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kYsx0Zcs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 440B8C433C7; Thu, 21 Dec 2023 10:54:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1703156088; bh=7wbXaePSW/44tnWXqKYDczbwgLzPWA8vIbnztprKJVI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=kYsx0Zcsdi/1Zy7bVVMDd7jKnpuL1iuXiAJ+Zx4z78WwYKtzB+LmUHXo/w2AOWmhe G6B4HfCLkoWYnzZBT6NzEh8fi18qMuewYIB3MdqKwrZmS0rhMfvHbCYjbHIKRPZmMS ZVm+0f3EKa8SiSEz9A3MGXEdCNwDWDttHikMqLY2ztaDlVTTsp/3+2qJcDPBmIKNPK VPF6NYn/Akw10Q8xQ1O4yGIHAS3BOlf6AkGWtWh1pOfwG4Shxu8ng/BzaMCNKyn8rQ /Ymd2HhpnLreiYdyNHyyL748eGqlO+hxaJNotg9gHRzCaXSC+JOqHAMogj08Fl7zu1 uGGl/fP3axycA== Date: Thu, 21 Dec 2023 10:54:34 +0000 From: Jonathan Cameron To: Rob Herring Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org, Frank Rowand , Jonathan Cameron Subject: Re: [RFC PATCH 1/4] of: Add cleanup.h based autorelease via __free(device_node) markings. Message-ID: <20231221105434.5842ff3a@jic23-huawei> In-Reply-To: <20231220221144.GA1188444-robh@kernel.org> References: <20231217184648.185236-1-jic23@kernel.org> <20231217184648.185236-2-jic23@kernel.org> <20231220221144.GA1188444-robh@kernel.org> X-Mailer: Claws Mail 4.2.0 (GTK 3.24.38; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 20 Dec 2023 16:11:44 -0600 Rob Herring wrote: > On Sun, Dec 17, 2023 at 06:46:45PM +0000, Jonathan Cameron wrote: > > From: Jonathan Cameron > > > > The recent addition of scope based cleanup support to the kernel > > provides a convenient tool to reduce the chances of leaking reference > > counts where of_node_put() should have been called in an error path. > > > > This enables > > struct device_node *child __free(device_node) = NULL; > > > > for_each_child_of_node(np, child) { > > if (test) > > return test; > > } > > > > with no need for a manual call of of_node_put() > > > > In this simile example the gains are small but there are some very > > typo > > > complex error handling cases burried in these loops that wil be > > greatly simplified by enabling early returns with out the need > > for this manual of_node_put() call. > > Neat! > > I guess that now that the coccinelle check has fixed many, we can update > it to the new way and start fixing them all again. We should update the > coccinelle script with the new way. See > scripts/coccinelle/iterators/for_each_child.cocci. If the holiday season gets dull enough I'll take a look at updating that as well. Been a long time since I last messed with coccinelle. Given this is just a simplification rather than a fix, there would be no rush to convert things over but we definitely don't want the coccinelle script to generate lots of false positives. + we should perhaps add a script to try and catch the opposite (double free) as a result of using this automated cleanup. > > > > > Signed-off-by: Jonathan Cameron > > --- > > include/linux/of.h | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/include/linux/of.h b/include/linux/of.h > > index 6a9ddf20e79a..50e882ee91da 100644 > > --- a/include/linux/of.h > > +++ b/include/linux/of.h > > @@ -13,6 +13,7 @@ > > */ > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -134,6 +135,7 @@ static inline struct device_node *of_node_get(struct device_node *node) > > } > > static inline void of_node_put(struct device_node *node) { } > > #endif /* !CONFIG_OF_DYNAMIC */ > > +DEFINE_FREE(device_node, struct device_node *, if (_T) of_node_put(_T)) > > of_node_put() can be called with NULL, so do we need the "if (_T)"? Nope - should be fine to call it without. I was being lazy and didn't check :) > > Rob