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authorDoug Anderson <dianders@chromium.org>2015-05-07 21:27:44 -0700
committerWim Van Sebroeck <wim@iguana.be>2015-06-22 15:54:31 +0200
commit7fb466a7a7362de19b8f2aa07cffa79e527cf070 (patch)
tree8f3253b98f415320f7cf003bfc5ec0d118ef4fd3 /drivers/watchdog
parent30dd4a8f08b570b5ed978fd937fdb5c31194be41 (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>
Diffstat (limited to 'drivers/watchdog')
-rw-r--r--drivers/watchdog/dw_wdt.c7
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;