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 <dianders@xxxxxxxxxxxx>
---
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
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