s3c2410_wdt watchdog driver: Locking and coding style

Kill off use of semaphores.
Fix ioctl races and locking holes.

From: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
index 98532c0e0689c93726976cb3507385321849f828..97b4a2e8eb09a62db3e5fa0eae184952be4e76b3 100644 (file)
--- a/drivers/watchdog/s3c2410_wdt.c
+++ b/drivers/watchdog/s3c2410_wdt.c
@@ -46,9 +46,8 @@
 #include <linux/platform_device.h>
 #include <linux/interrupt.h>
 #include <linux/clk.h>
-
-#include <asm/uaccess.h>
-#include <asm/io.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
 
 #include <asm/arch/map.h>
 
@@ -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)
 {