linux-kernel - Re: [PATCH 1/5] clk: add missing of_node

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Date:	Wed, 21 Oct 2015 16:13:10 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Julia Lawall <Julia.Lawall@...6.fr>
Cc:	Michael Turquette <mturquette@...libre.com>,
	kernel-janitors@...r.kernel.org, linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Andrew Lunn <andrew@...n.ch>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Jason Cooper <jason@...edaemon.net>
Subject: Re: [PATCH 1/5] clk: add missing of_node_put

On 10/21, Julia Lawall wrote:
> for_each_matching_node_and_match performs an of_node_get on each iteration,
> so a break out of the loop requires an of_node_put.
> 
> A simplified version of the semantic patch that fixes this problem is as
> follows (http://coccinelle.lip6.fr):
> 
> // <smpl>
> @@
> expression e1,e2,e;
> local idexpression np;
> @@
> 
>  for_each_matching_node_and_match(np, e1, e2) {
>    ... when != of_node_put(np)
>        when != e = np
> (
>    return np;
> |
> +  of_node_put(np);
> ?  return ...;
> )
>    ...
>  }
> // </smpl>
> 
> Besides the problem identified by the semantic patch, this patch adds an
> of_node_get in front of saving np in a field of parent, to account for the
> fact that this value will be put on going on to the next element in the
> iteration, and then adds of_node_puts in the two loops where the parent
> pointer can be freed.
> 
> Signed-off-by: Julia Lawall <Julia.Lawall@...6.fr>
> 
> ---

Applied to clk-next, except I collapsed the of_node_get() into
the assignment.

---8<---
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index d366bfb66c58..2eae76f21d6f 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -3205,8 +3205,7 @@ void __init of_clk_init(const struct of_device_id *matches)
 		}
 
 		parent->clk_init_cb = match->data;
-		of_node_get(np);
-		parent->np = np;
+		parent->np = of_node_get(np);
 		list_add_tail(&parent->node, &clk_provider_list);
 	}
 

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