ARM: SAMSUNG: Use spin_lock_{irqsave,irqrestore} in clk_set_rate

trbehera · kgene · commit d6838a62b4d3 · 2012-09-18T10:05:34.000+09:00
The spinlock clocks_lock can be held during ISR, hence it is not safe to hold that lock with disabling interrupts. It fixes following potential deadlock. ========================================================= [ INFO: possible irq lock inversion dependency detected ] 3.6.0-rc4+ #2 Not tainted --------------------------------------------------------- swapper/0/1 just changed the state of lock: (&(&host->lock)->rlock){-.....}, at: [<c027fb0d>] sdhci_irq+0x15/0x564 but this lock took another, HARDIRQ-unsafe lock in the past: (clocks_lock){+.+...} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(clocks_lock); local_irq_disable(); lock(&(&host->lock)->rlock); lock(clocks_lock); <Interrupt> lock(&(&host->lock)->rlock); *** DEADLOCK *** Signed-off-by: Tushar Behera <tushar.behera@linaro.org> Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
diff --git a/arch/arm/plat-samsung/clock.c b/arch/arm/plat-samsung/clock.c
@@ -144,6 +144,7 @@ long clk_round_rate(struct clk *clk, unsigned long rate)
 
 int clk_set_rate(struct clk *clk, unsigned long rate)
 {
+	unsigned long flags;
 	int ret;
 
 	if (IS_ERR(clk))
@@ -159,9 +160,9 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 	if (clk->ops == NULL || clk->ops->set_rate == NULL)
 		return -EINVAL;
 
-	spin_lock(&clocks_lock);
+	spin_lock_irqsave(&clocks_lock, flags);
 	ret = (clk->ops->set_rate)(clk, rate);
-	spin_unlock(&clocks_lock);
+	spin_unlock_irqrestore(&clocks_lock, flags);
 
 	return ret;
 }
