From patchwork Sun Jan 28 16:05:38 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 13534510 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 338CF2C850; Sun, 28 Jan 2024 16:06:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706457969; cv=none; b=R/ihIY1Tr94nNWDcm6pypm3nQbF03n0u+zaw2qZ8c71pqEXJmyUOmHVp53LKVG78gL5Uimg6zL0IHWACGJ/kXpDbTtrodP33TGwn6xwmOJASFipID3kxVybaytVu7lIItBQ/SOJMltkoCnPrZnt88tLGWv3+xVKLbt7RWdyXxgw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706457969; c=relaxed/simple; bh=yeij2zd0BfAatAVK4xbn+gh4HqFxqVbeELw/h09d40M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=itT9UpRPTikvLRkXfQGUIMe1TTTqYLvYgRhTnwr2gZgB9yK2whr07cC4bE0puKsbHDasnWW8nq3D7rOQQv4K2r1mN85cfqOa2I9THbfMGF0tCnLMZuiGam7XoJG1fRQEN2KWds8kUTiZCGChkCFy6vaLqb2zcvEPfNZaYz6ygCg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jb2HZ1kE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jb2HZ1kE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A14FBC433C7; Sun, 28 Jan 2024 16:06:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706457968; bh=yeij2zd0BfAatAVK4xbn+gh4HqFxqVbeELw/h09d40M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jb2HZ1kEkbL0DLPQcYUxBWFWA7qb8nt71qZmUTAr5BnSXXpsHKdsiClKo21MNV6RI bBUGqmXuF6hfD06WHH9DiGveI40ItBUmgxLczStwAVBciTKvjJ9Gglrkki2xCkcmh7 fvl9qg9PolIQflEtnDyLyheTTTBWPJVeNa/Z0gzoC6+BhAiSmF1vI2fQjNhvU61gVy OqA8fRmohjQxuB/C5hknO1wWRPvUT39YxvAycjzTrzJaiS9li3WvEF4Dad+UOI81Wx UMXRWSu46uoMJdmr5u6S6dk5ZMUIDNmpfwPWkJVMUABsg/mh4u64103CkX8UBYq5MK cmJYh1bVV6oUg== From: Jonathan Cameron To: linux-iio@vger.kernel.org, Rob Herring , Frank Rowand , linux-kernel@vger.kernel.org Cc: Julia Lawall , Nicolas Palix , Sumera Priyadarsini , "Rafael J . Wysocki" , Len Brown , linux-acpi@vger.kernel.org, Andy Shevchenko , Greg Kroah-Hartman , =?utf-8?q?Nuno_S=C3=A1?= , Jonathan Cameron Subject: [RFC PATCH 1/5] of: Add cleanup.h based auto release via __free(device_node) markings. Date: Sun, 28 Jan 2024 16:05:38 +0000 Message-ID: <20240128160542.178315-2-jic23@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240128160542.178315-1-jic23@kernel.org> References: <20240128160542.178315-1-jic23@kernel.org> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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(). A following patch will reduce the scope of the child variable to the for loop, to avoid an issues with ordering of autocleanup, and make it obvious when this assigned a non NULL value. In this simple example the gains are small but there are some very complex error handling cases buried in these loops that will be greatly simplified by enabling early returns with out the need for this manual of_node_put() call. Note that there are coccinelle checks in scripts/coccinelle/iterators/for_each_child.cocci to detect a failure to call of_node_put(). This new approach does not cause false positives. Longer term we may want to add scripting to check this new approach is done correctly with no double of_node_put() calls being introduced due to the auto cleanup. It may also be useful to script finding places this new approach is useful. 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)) /* Pointer for first entry in chain of all nodes. */ extern struct device_node *of_root;