From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: From: Doug Anderson To: wim@iguana.be, linux@roeck-us.net Cc: jszhang@marvell.com, Doug Anderson , linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] watchdog: dw_wdt: Use a mutex, not a spinlock Date: Thu, 7 May 2015 15:09:23 -0700 Message-Id: <1431036564-4189-1-git-send-email-dianders@chromium.org> List-ID: 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 --- 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 #include #include +#include #include #include #include #include #include -#include #include #include #include @@ -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