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

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Date:	Thu, 22 Oct 2015 07:52:29 +0200 (CEST)
From:	Julia Lawall <julia.lawall@...6.fr>
To:	Stephen Boyd <sboyd@...eaurora.org>
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 Wed, 21 Oct 2015, Stephen Boyd wrote:

> 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);

Thanks!

julia

>  		list_add_tail(&parent->node, &clk_provider_list);
>  	}
>  
> 
> -- 
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> a Linux Foundation Collaborative Project
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