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>

1 files changed, 17 insertions, 12 deletions

diff --git a/drivers/watchdog/ar7_wdt.c b/drivers/watchdog/ar7_wdt.c
index 2eb48c0df32..ef7b0d67095 100644
--- 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