From 41dc8b72e37c514f7332cbc3f3dd864910c2a1fa Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Mon, 4 Aug 2008 17:54:46 +0100 Subject: [PATCH] s3c2410_wdt watchdog driver: Locking and coding style Kill off use of semaphores. Fix ioctl races and locking holes. From: Alan Cox Signed-off-by: Andrew Morton Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- drivers/watchdog/s3c2410_wdt.c | 148 ++++++++++++++++++--------------- 1 file changed, 80 insertions(+), 68 deletions(-) diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c index 98532c0e0689..97b4a2e8eb09 100644 --- a/drivers/watchdog/s3c2410_wdt.c +++ b/drivers/watchdog/s3c2410_wdt.c @@ -46,9 +46,8 @@ #include #include #include - -#include -#include +#include +#include #include @@ -65,8 +64,8 @@ static int nowayout = WATCHDOG_NOWAYOUT; static int tmr_margin = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME; static int tmr_atboot = CONFIG_S3C2410_WATCHDOG_ATBOOT; -static int soft_noboot = 0; -static int debug = 0; +static int soft_noboot; +static int debug; module_param(tmr_margin, int, 0); module_param(tmr_atboot, int, 0); @@ -74,24 +73,23 @@ module_param(nowayout, int, 0); module_param(soft_noboot, int, 0); module_param(debug, int, 0); -MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")"); - -MODULE_PARM_DESC(tmr_atboot, "Watchdog is started at boot time if set to 1, default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT)); - -MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); - +MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default=" + __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")"); +MODULE_PARM_DESC(tmr_atboot, + "Watchdog is started at boot time if set to 1, default=" + __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT)); +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)"); - MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)"); typedef enum close_state { CLOSE_STATE_NOT, - CLOSE_STATE_ALLOW=0x4021 + CLOSE_STATE_ALLOW = 0x4021 } close_state_t; -static DECLARE_MUTEX(open_lock); - +static unsigned long open_lock; static struct device *wdt_dev; /* platform device attached to */ static struct resource *wdt_mem; static struct resource *wdt_irq; @@ -99,38 +97,58 @@ static struct clk *wdt_clock; static void __iomem *wdt_base; static unsigned int wdt_count; static close_state_t allow_close; +static DEFINE_SPINLOCK(wdt_lock); /* watchdog control routines */ #define DBG(msg...) do { \ if (debug) \ printk(KERN_INFO msg); \ - } while(0) + } while (0) /* functions */ -static int s3c2410wdt_keepalive(void) +static void s3c2410wdt_keepalive(void) { + spin_lock(&wdt_lock); writel(wdt_count, wdt_base + S3C2410_WTCNT); - return 0; + spin_unlock(&wdt_lock); } -static int s3c2410wdt_stop(void) +static void __s3c2410wdt_stop(void) { unsigned long wtcon; + spin_lock(&wdt_lock); wtcon = readl(wdt_base + S3C2410_WTCON); wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN); writel(wtcon, wdt_base + S3C2410_WTCON); + spin_unlock(&wdt_lock); +} - return 0; +static void __s3c2410wdt_stop(void) +{ + unsigned long wtcon; + + wtcon = readl(wdt_base + S3C2410_WTCON); + wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN); + writel(wtcon, wdt_base + S3C2410_WTCON); +} + +static void s3c2410wdt_stop(void) +{ + spin_lock(&wdt_lock); + __s3c2410wdt_stop(); + spin_unlock(&wdt_lock); } -static int s3c2410wdt_start(void) +static void s3c2410wdt_start(void) { unsigned long wtcon; - s3c2410wdt_stop(); + spin_lock(&wdt_lock); + + __s3c2410wdt_stop(); wtcon = readl(wdt_base + S3C2410_WTCON); wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128; @@ -149,6 +167,7 @@ static int s3c2410wdt_start(void) writel(wdt_count, wdt_base + S3C2410_WTDAT); writel(wdt_count, wdt_base + S3C2410_WTCNT); writel(wtcon, wdt_base + S3C2410_WTCON); + spin_unlock(&wdt_lock); return 0; } @@ -211,7 +230,7 @@ static int s3c2410wdt_set_heartbeat(int timeout) static int s3c2410wdt_open(struct inode *inode, struct file *file) { - if(down_trylock(&open_lock)) + if (test_and_set_bit(0, &open_lock)) return -EBUSY; if (nowayout) @@ -231,15 +250,14 @@ static int s3c2410wdt_release(struct inode *inode, struct file *file) * Lock it in if it's a module and we set nowayout */ - if (allow_close == CLOSE_STATE_ALLOW) { + if (allow_close == CLOSE_STATE_ALLOW) s3c2410wdt_stop(); - } else { + else { dev_err(wdt_dev, "Unexpected close, not stopping watchdog\n"); s3c2410wdt_keepalive(); } - allow_close = CLOSE_STATE_NOT; - up(&open_lock); + clear_bit(0, &open_lock); return 0; } @@ -249,7 +267,7 @@ static ssize_t s3c2410wdt_write(struct file *file, const char __user *data, /* * Refresh the timer. */ - if(len) { + if (len) { if (!nowayout) { size_t i; @@ -265,7 +283,6 @@ static ssize_t s3c2410wdt_write(struct file *file, const char __user *data, allow_close = CLOSE_STATE_ALLOW; } } - s3c2410wdt_keepalive(); } return len; @@ -273,48 +290,41 @@ static ssize_t s3c2410wdt_write(struct file *file, const char __user *data, #define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE -static struct watchdog_info s3c2410_wdt_ident = { +static const struct watchdog_info s3c2410_wdt_ident = { .options = OPTIONS, .firmware_version = 0, .identity = "S3C2410 Watchdog", }; -static int s3c2410wdt_ioctl(struct inode *inode, struct file *file, - unsigned int cmd, unsigned long arg) +static long s3c2410wdt_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) { void __user *argp = (void __user *)arg; int __user *p = argp; int new_margin; switch (cmd) { - default: - return -ENOTTY; - - case WDIOC_GETSUPPORT: - return copy_to_user(argp, &s3c2410_wdt_ident, - sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0; - - case WDIOC_GETSTATUS: - case WDIOC_GETBOOTSTATUS: - return put_user(0, p); - - case WDIOC_KEEPALIVE: - s3c2410wdt_keepalive(); - return 0; - - case WDIOC_SETTIMEOUT: - if (get_user(new_margin, p)) - return -EFAULT; - - if (s3c2410wdt_set_heartbeat(new_margin)) - return -EINVAL; - - s3c2410wdt_keepalive(); - return put_user(tmr_margin, p); - - case WDIOC_GETTIMEOUT: - return put_user(tmr_margin, p); + default: + return -ENOTTY; + case WDIOC_GETSUPPORT: + return copy_to_user(argp, &s3c2410_wdt_ident, + sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0; + case WDIOC_GETSTATUS: + case WDIOC_GETBOOTSTATUS: + return put_user(0, p); + case WDIOC_KEEPALIVE: + s3c2410wdt_keepalive(); + return 0; + case WDIOC_SETTIMEOUT: + if (get_user(new_margin, p)) + return -EFAULT; + if (s3c2410wdt_set_heartbeat(new_margin)) + return -EINVAL; + s3c2410wdt_keepalive(); + return put_user(tmr_margin, p); + case WDIOC_GETTIMEOUT: + return put_user(tmr_margin, p); } } @@ -324,7 +334,7 @@ static const struct file_operations s3c2410wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .write = s3c2410wdt_write, - .ioctl = s3c2410wdt_ioctl, + .unlocked_ioctl = s3c2410wdt_ioctl, .open = s3c2410wdt_open, .release = s3c2410wdt_release, }; @@ -411,14 +421,15 @@ static int s3c2410wdt_probe(struct platform_device *pdev) * not, try the default value */ if (s3c2410wdt_set_heartbeat(tmr_margin)) { - started = s3c2410wdt_set_heartbeat(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME); + started = s3c2410wdt_set_heartbeat( + CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME); - if (started == 0) { - dev_info(dev,"tmr_margin value out of range, default %d used\n", + if (started == 0) + dev_info(dev, + "tmr_margin value out of range, default %d used\n", CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME); - } else { + else dev_info(dev, "default timer value is out of range, cannot start\n"); - } } ret = misc_register(&s3c2410wdt_miscdev); @@ -447,7 +458,7 @@ static int s3c2410wdt_probe(struct platform_device *pdev) (wtcon & S3C2410_WTCON_ENABLE) ? "" : "in", (wtcon & S3C2410_WTCON_RSTEN) ? "" : "dis", (wtcon & S3C2410_WTCON_INTEN) ? "" : "en"); - + return 0; err_clk: @@ -487,7 +498,7 @@ static int s3c2410wdt_remove(struct platform_device *dev) static void s3c2410wdt_shutdown(struct platform_device *dev) { - s3c2410wdt_stop(); + s3c2410wdt_stop(); } #ifdef CONFIG_PM @@ -540,7 +551,8 @@ static struct platform_driver s3c2410wdt_driver = { }; -static char banner[] __initdata = KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n"; +static char banner[] __initdata = + KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n"; static int __init watchdog_init(void) { -- 2.39.5