Right now the dw_wdt uses a spinlock to protect dw_wdt_open(). The problem is that while holding the spinlock we call: -> dw_wdt_set_top() -> dw_wdt_top_in_seconds() -> clk_get_rate() -> clk_prepare_lock() -> mutex_lock()
Locking a mutex while holding a spinlock is not allowed and leads to warnings like "BUG: spinlock wrong CPU on CPU#1", among other problems. There's no reason to use a spinlock, so switch to a mutex. Signed-off-by: Doug Anderson <diand...@chromium.org> --- drivers/watchdog/dw_wdt.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c index d0bb949..3fa2f19 100644 --- a/drivers/watchdog/dw_wdt.c +++ b/drivers/watchdog/dw_wdt.c @@ -30,12 +30,12 @@ #include <linux/miscdevice.h> #include <linux/module.h> #include <linux/moduleparam.h> +#include <linux/mutex.h> #include <linux/notifier.h> #include <linux/of.h> #include <linux/pm.h> #include <linux/platform_device.h> #include <linux/reboot.h> -#include <linux/spinlock.h> #include <linux/timer.h> #include <linux/uaccess.h> #include <linux/watchdog.h> @@ -61,7 +61,7 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " #define WDT_TIMEOUT (HZ / 2) static struct { - spinlock_t lock; + struct mutex lock; void __iomem *regs; struct clk *clk; unsigned long in_use; @@ -177,7 +177,7 @@ static int dw_wdt_open(struct inode *inode, struct file *filp) /* Make sure we don't get unloaded. */ __module_get(THIS_MODULE); - spin_lock(&dw_wdt.lock); + mutex_lock(&dw_wdt.lock); if (!dw_wdt_is_enabled()) { /* * The watchdog is not currently enabled. Set the timeout to @@ -190,7 +190,7 @@ static int dw_wdt_open(struct inode *inode, struct file *filp) dw_wdt_set_next_heartbeat(); - spin_unlock(&dw_wdt.lock); + mutex_unlock(&dw_wdt.lock); return nonseekable_open(inode, filp); } @@ -348,7 +348,7 @@ static int dw_wdt_drv_probe(struct platform_device *pdev) if (ret) return ret; - spin_lock_init(&dw_wdt.lock); + mutex_init(&dw_wdt.lock); ret = misc_register(&dw_wdt_miscdev); if (ret) -- 2.2.0.rc0.207.ga3a616c -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/