linux-kernel - Re: [RFC PATCH 02/34] msm: clock: Always use an array to iterate over clocks

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Message-ID: <20111102194555.GE12913@n2100.arm.linux.org.uk>
Date:	Wed, 2 Nov 2011 19:45:55 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	David Brown <davidb@...eaurora.org>
Cc:	Daniel Walker <dwalker@...o99.com>,
	Bryan Huntsman <bryanh@...eaurora.org>,
	linux-arm-msm@...r.kernel.org, Stephen Boyd <sboyd@...eaurora.org>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH 02/34] msm: clock: Always use an array to iterate
	over clocks

On Wed, Nov 02, 2011 at 11:35:59AM -0700, David Brown wrote:
> If the array of clk_lookups contains aliases for the same struct
> clk, msm_clock_init() will add the clock to the clocks list
> twice.  This would cause list corruption so let's just remove the
> clocks list and any associated code and iterate over the array
> instead.

Hmm...

> @@ -158,13 +152,13 @@ void __init msm_clock_init(struct clk_lookup *clock_tbl, unsigned num_clocks)
>   */
>  static int __init clock_late_init(void)
>  {
> +	unsigned i, count = 0;
>  	unsigned long flags;
> -	struct clk *clk;
> -	unsigned count = 0;
>  
>  	clock_debug_init();
> -	mutex_lock(&clocks_mutex);
> -	list_for_each_entry(clk, &clocks, list) {
> +	for (i = 0; i < msm_num_clocks; i++) {
> +		struct clk *clk = msm_clocks[i].clk;
> +
>  		clock_debug_add(clk);

This means you'll end up calling clock_debug_add() twice for the same
struct clk - this sounds like a bad idea in itself.  It looks like
there's no protection within that function against it being called
twice with the same struct clk.

Are you sure this is safe?
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