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Commit 6e2ad511 authored by Ole Henrik Jahren's avatar Ole Henrik Jahren Committed by Hans-Christian Egtvedt
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avr32: fix deadlock when reading clock list in debugfs 



When writing out /sys/kernel/debug/at32ap_clk, clock list lock is being
held while clk_get() is called. clk_get() attempts to take the same
lock, which results in deadlock. Introduce and call lock free version,
__clk_get(), instead.

Signed-off-by: default avatarOle Henrik Jahren <olehenja@alumni.ntnu.no>
Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Signed-off-by: default avatarHans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
parent 51ef85d8

arch/avr32/mach-at32ap/clock.c

+16 −8
Original line number Original line Diff line number Diff line
@@ -35,22 +35,30 @@ void at32_clk_register(struct clk *clk) 
	spin_unlock(&clk_list_lock);

	spin_unlock(&clk_list_lock);

}

}





struct clk *clk_get(struct device *dev, const char *id)

static struct clk *__clk_get(struct device *dev, const char *id)

{

{

	struct clk *clk;

	struct clk *clk;





	spin_lock(&clk_list_lock);



	list_for_each_entry(clk, &at32_clock_list, list) {

	list_for_each_entry(clk, &at32_clock_list, list) {

		if (clk->dev == dev && strcmp(id, clk->name) == 0) {

		if (clk->dev == dev && strcmp(id, clk->name) == 0) {

			spin_unlock(&clk_list_lock);

			return clk;

			return clk;

		}

		}

	}

	}





	spin_unlock(&clk_list_lock);

	return ERR_PTR(-ENOENT);

	return ERR_PTR(-ENOENT);

}

}



struct clk *clk_get(struct device *dev, const char *id)

{

	struct clk *clk;



	spin_lock(&clk_list_lock);

	clk = __clk_get(dev, id);

	spin_unlock(&clk_list_lock);



	return clk;

}



EXPORT_SYMBOL(clk_get);

EXPORT_SYMBOL(clk_get);





void clk_put(struct clk *clk)

void clk_put(struct clk *clk)
@@ -257,15 +265,15 @@ static int clk_show(struct seq_file *s, void *unused) 
	spin_lock(&clk_list_lock);

	spin_lock(&clk_list_lock);





	/* show clock tree as derived from the three oscillators */

	/* show clock tree as derived from the three oscillators */

	clk = clk_get(NULL, "osc32k");

	clk = __clk_get(NULL, "osc32k");

	dump_clock(clk, &r);

	dump_clock(clk, &r);

	clk_put(clk);

	clk_put(clk);





	clk = clk_get(NULL, "osc0");

	clk = __clk_get(NULL, "osc0");

	dump_clock(clk, &r);

	dump_clock(clk, &r);

	clk_put(clk);

	clk_put(clk);





	clk = clk_get(NULL, "osc1");

	clk = __clk_get(NULL, "osc1");

	dump_clock(clk, &r);

	dump_clock(clk, &r);

	clk_put(clk);

	clk_put(clk);