diff options
| author | Doug Anderson <dianders@chromium.org> | 2015-05-07 21:27:44 -0700 |
|---|---|---|
| committer | Wim Van Sebroeck <wim@iguana.be> | 2015-06-22 15:54:31 +0200 |
| commit | 7fb466a7a7362de19b8f2aa07cffa79e527cf070 (patch) | |
| tree | 8f3253b98f415320f7cf003bfc5ec0d118ef4fd3 | |
| parent | 30dd4a8f08b570b5ed978fd937fdb5c31194be41 (diff) | |
watchdog: dw_wdt: No need for a spinlock
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. Only dw_wdt_open() was protected
and the test_and_set_bit() at the start of that function protects us
anyway.
Signed-off-by: Doug Anderson <dianders@chromium.org>
Tested-by: Jisheng Zhang <jszhang@marvell.com>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
| -rw-r--r-- | drivers/watchdog/dw_wdt.c | 7 |
1 files changed, 0 insertions, 7 deletions
diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c index d0bb9499d12c..a284abdb4fb6 100644 --- a/drivers/watchdog/dw_wdt.c +++ b/drivers/watchdog/dw_wdt.c @@ -35,7 +35,6 @@ #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 +60,6 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " #define WDT_TIMEOUT (HZ / 2) static struct { - spinlock_t lock; void __iomem *regs; struct clk *clk; unsigned long in_use; @@ -177,7 +175,6 @@ 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); if (!dw_wdt_is_enabled()) { /* * The watchdog is not currently enabled. Set the timeout to @@ -190,8 +187,6 @@ static int dw_wdt_open(struct inode *inode, struct file *filp) dw_wdt_set_next_heartbeat(); - spin_unlock(&dw_wdt.lock); - return nonseekable_open(inode, filp); } @@ -348,8 +343,6 @@ static int dw_wdt_drv_probe(struct platform_device *pdev) if (ret) return ret; - spin_lock_init(&dw_wdt.lock); - ret = misc_register(&dw_wdt_miscdev); if (ret) goto out_disable_clk; |