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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: Ole Henrik Jahren <olehenja@alumni.ntnu.no>
Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
This commit is contained in:
Ole Henrik Jahren 2011-03-06 20:42:39 +01:00 committed by Hans-Christian Egtvedt
parent 51ef85d8f9
commit 6e2ad51190
1 changed files with 20 additions and 12 deletions
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32
arch/avr32/mach-at32ap/clock.c
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@ -35,22 +35,30 @@ void at32_clk_register(struct clk *clk)
spin_unlock(&clk_list_lock);
}
static struct clk *__clk_get(struct device *dev, const char *id)
{
struct clk *clk;
list_for_each_entry(clk, &at32_clock_list, list) {
if (clk->dev == dev && strcmp(id, clk->name) == 0) {
return clk;
}
}
return ERR_PTR(-ENOENT);
}
struct clk *clk_get(struct device *dev, const char *id)
{
struct clk *clk;
spin_lock(&clk_list_lock);
list_for_each_entry(clk, &at32_clock_list, list) {
if (clk->dev == dev && strcmp(id, clk->name) == 0) {
spin_unlock(&clk_list_lock);
return clk;
}
}
clk = __clk_get(dev, id);
spin_unlock(&clk_list_lock);
return ERR_PTR(-ENOENT);
return clk;
}
EXPORT_SYMBOL(clk_get);
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);
/* show clock tree as derived from the three oscillators */
clk = clk_get(NULL, "osc32k");
clk = __clk_get(NULL, "osc32k");
dump_clock(clk, &r);
clk_put(clk);
clk = clk_get(NULL, "osc0");
clk = __clk_get(NULL, "osc0");
dump_clock(clk, &r);
clk_put(clk);
clk = clk_get(NULL, "osc1");
clk = __clk_get(NULL, "osc1");
dump_clock(clk, &r);
clk_put(clk);