ar7_wdt watchdog driver: Fix locking

Use unlocked_ioctl
Remove semaphores

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

diff --git a/drivers/watchdog/ar7_wdt.c b/drivers/watchdog/ar7_wdt.c
index 2eb48c0df32c9889fa93e0d4123912f735f6f1c7..ef7b0d67095ea8ee053731eb6e66cb9835e6ce19 100644 (file)
--- a/drivers/watchdog/ar7_wdt.c
+++ b/drivers/watchdog/ar7_wdt.c
@@ -69,7 +69,8 @@ struct ar7_wdt {
        u32 prescale;
 };
 
-static struct semaphore open_semaphore;
+static unsigned long wdt_is_open;
+static spinlock_t wdt_lock;
 static unsigned expect_close;
 
 /* XXX currently fixed, allows max margin ~68.72 secs */
@@ -154,8 +155,10 @@ static void ar7_wdt_update_margin(int new_margin)
        u32 change;
 
        change = new_margin * (ar7_vbus_freq() / prescale_value);
-       if (change < 1) change = 1;
-       if (change > 0xffff) change = 0xffff;
+       if (change < 1)
+               change = 1;
+       if (change > 0xffff)
+               change = 0xffff;
        ar7_wdt_change(change);
        margin = change * prescale_value / ar7_vbus_freq();
        printk(KERN_INFO DRVNAME
@@ -179,7 +182,7 @@ static void ar7_wdt_disable_wdt(void)
 static int ar7_wdt_open(struct inode *inode, struct file *file)
 {
        /* only allow one at a time */
-       if (down_trylock(&open_semaphore))
+       if (test_and_set_bit(0, &wdt_is_open))
                return -EBUSY;
        ar7_wdt_enable_wdt();
        expect_close = 0;
@@ -195,9 +198,7 @@ static int ar7_wdt_release(struct inode *inode, struct file *file)
                "will not disable the watchdog timer\n");
        else if (!nowayout)
                ar7_wdt_disable_wdt();
-
-       up(&open_semaphore);
-
+       clear_bit(0, &wdt_is_open);
        return 0;
 }
 
@@ -222,7 +223,9 @@ static ssize_t ar7_wdt_write(struct file *file, const char *data,
        if (len) {
                size_t i;
 
+               spin_lock(&wdt_lock);
                ar7_wdt_kick(1);
+               spin_unlock(&wdt_lock);
 
                expect_close = 0;
                for (i = 0; i < len; ++i) {
@@ -237,8 +240,8 @@ static ssize_t ar7_wdt_write(struct file *file, const char *data,
        return len;
 }
 
-static int ar7_wdt_ioctl(struct inode *inode, struct file *file,
-                        unsigned int cmd, unsigned long arg)
+static long ar7_wdt_ioctl(struct file *file,
+                                       unsigned int cmd, unsigned long arg)
 {
        static struct watchdog_info ident = {
                .identity = LONGNAME,
@@ -269,8 +272,10 @@ static int ar7_wdt_ioctl(struct inode *inode, struct file *file,
                if (new_margin < 1)
                        return -EINVAL;
 
+               spin_lock(&wdt_lock);
                ar7_wdt_update_margin(new_margin);
                ar7_wdt_kick(1);
+               spin_unlock(&wdt_lock);
 
        case WDIOC_GETTIMEOUT:
                if (put_user(margin, (int *)arg))
@@ -282,7 +287,7 @@ static int ar7_wdt_ioctl(struct inode *inode, struct file *file,
 static const struct file_operations ar7_wdt_fops = {
        .owner          = THIS_MODULE,
        .write          = ar7_wdt_write,
-       .ioctl          = ar7_wdt_ioctl,
+       .unlocked_ioctl = ar7_wdt_ioctl,
        .open           = ar7_wdt_open,
        .release        = ar7_wdt_release,
 };
@@ -297,6 +302,8 @@ static int __init ar7_wdt_init(void)
 {
        int rc;
 
+       spin_lock_init(&wdt_lock);
+
        ar7_wdt_get_regs();
 
        if (!request_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt),
@@ -312,8 +319,6 @@ static int __init ar7_wdt_init(void)
        ar7_wdt_prescale(prescale_value);
        ar7_wdt_update_margin(margin);
 
-       sema_init(&open_semaphore, 1);
-
        rc = register_reboot_notifier(&ar7_wdt_notifier);
        if (rc) {
                printk(KERN_ERR DRVNAME