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>
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@ -35,7 +35,6 @@
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#include <linux/pm.h>
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#include <linux/pm.h>
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#include <linux/platform_device.h>
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#include <linux/platform_device.h>
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#include <linux/reboot.h>
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#include <linux/reboot.h>
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#include <linux/spinlock.h>
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#include <linux/timer.h>
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#include <linux/timer.h>
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#include <linux/uaccess.h>
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#include <linux/uaccess.h>
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#include <linux/watchdog.h>
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#include <linux/watchdog.h>
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@ -61,7 +60,6 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
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#define WDT_TIMEOUT (HZ / 2)
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#define WDT_TIMEOUT (HZ / 2)
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static struct {
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static struct {
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spinlock_t lock;
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void __iomem *regs;
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void __iomem *regs;
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struct clk *clk;
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struct clk *clk;
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unsigned long in_use;
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unsigned long in_use;
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@ -177,7 +175,6 @@ static int dw_wdt_open(struct inode *inode, struct file *filp)
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/* Make sure we don't get unloaded. */
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/* Make sure we don't get unloaded. */
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__module_get(THIS_MODULE);
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__module_get(THIS_MODULE);
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spin_lock(&dw_wdt.lock);
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if (!dw_wdt_is_enabled()) {
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if (!dw_wdt_is_enabled()) {
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/*
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/*
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* The watchdog is not currently enabled. Set the timeout to
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* The watchdog is not currently enabled. Set the timeout to
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@ -190,8 +187,6 @@ static int dw_wdt_open(struct inode *inode, struct file *filp)
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dw_wdt_set_next_heartbeat();
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dw_wdt_set_next_heartbeat();
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spin_unlock(&dw_wdt.lock);
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return nonseekable_open(inode, filp);
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return nonseekable_open(inode, filp);
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}
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}
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@ -348,8 +343,6 @@ static int dw_wdt_drv_probe(struct platform_device *pdev)
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if (ret)
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if (ret)
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return ret;
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return ret;
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spin_lock_init(&dw_wdt.lock);
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ret = misc_register(&dw_wdt_miscdev);
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ret = misc_register(&dw_wdt_miscdev);
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if (ret)
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if (ret)
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goto out_disable_clk;
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goto out_disable_clk;
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