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>
diff --git a/arch/avr32/mach-at32ap/clock.c b/arch/avr32/mach-at32ap/clock.c
index 442f08c..86925fd 100644
--- a/arch/avr32/mach-at32ap/clock.c
+++ b/arch/avr32/mach-at32ap/clock.c
@@ -35,22 +35,30 @@
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 @@
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);