[PATCH] tlclk: bug fix + misc fixes

The following patch fixes a few problems with the tlclk driver.
* bug in the select_amcb1_transmit_clock
* racy read sys call
* racy open sys call
* use of add_timer where mod_timer would be better
* change to the timer data parameter use

Signed-off-by: Mark Gross <mark.gross@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/char/tlclk.c b/drivers/char/tlclk.c
index 448d5083c3810abf73d0ea647c44773c5bc52508..4fac2bdf62156e48fa036c2516ae42b2019aac33 100644 (file)
--- a/drivers/char/tlclk.c
+++ b/drivers/char/tlclk.c
@@ -186,6 +186,7 @@ static int got_event;               /* if events processing have been done */
 static void switchover_timeout(unsigned long data);
 static struct timer_list switchover_timer =
        TIMER_INITIALIZER(switchover_timeout , 0, 0);
+static unsigned long tlclk_timer_data;
 
 static struct tlclk_alarms *alarm_events;
 
@@ -197,10 +198,19 @@ static irqreturn_t tlclk_interrupt(int irq, void *dev_id);
 
 static DECLARE_WAIT_QUEUE_HEAD(wq);
 
+static unsigned long useflags;
+static DEFINE_MUTEX(tlclk_mutex);
+
 static int tlclk_open(struct inode *inode, struct file *filp)
 {
        int result;
 
+       if (test_and_set_bit(0, &useflags))
+               return -EBUSY;
+               /* this legacy device is always one per system and it doesn't
+                * know how to handle multiple concurrent clients.
+                */
+
        /* Make sure there is no interrupt pending while
         * initialising interrupt handler */
        inb(TLCLK_REG6);
@@ -221,6 +231,7 @@ static int tlclk_open(struct inode *inode, struct file *filp)
 static int tlclk_release(struct inode *inode, struct file *filp)
 {
        free_irq(telclk_interrupt, tlclk_interrupt);
+       clear_bit(0, &useflags);
 
        return 0;
 }
@@ -230,26 +241,25 @@ static ssize_t tlclk_read(struct file *filp, char __user *buf, size_t count,
 {
        if (count < sizeof(struct tlclk_alarms))
                return -EIO;
+       if (mutex_lock_interruptible(&tlclk_mutex))
+               return -EINTR;
+
 
        wait_event_interruptible(wq, got_event);
-       if (copy_to_user(buf, alarm_events, sizeof(struct tlclk_alarms)))
+       if (copy_to_user(buf, alarm_events, sizeof(struct tlclk_alarms))) {
+               mutex_unlock(&tlclk_mutex);
                return -EFAULT;
+       }
 
        memset(alarm_events, 0, sizeof(struct tlclk_alarms));
        got_event = 0;
 
+       mutex_unlock(&tlclk_mutex);
        return  sizeof(struct tlclk_alarms);
 }
 
-static ssize_t tlclk_write(struct file *filp, const char __user *buf, size_t count,
-           loff_t *f_pos)
-{
-       return 0;
-}
-
 static const struct file_operations tlclk_fops = {
        .read = tlclk_read,
-       .write = tlclk_write,
        .open = tlclk_open,
        .release = tlclk_release,
 
@@ -540,7 +550,7 @@ static ssize_t store_select_amcb1_transmit_clock(struct device *d,
                        SET_PORT_BITS(TLCLK_REG3, 0xf8, 0x7);
                        switch (val) {
                        case CLK_8_592MHz:
-                               SET_PORT_BITS(TLCLK_REG0, 0xfc, 1);
+                               SET_PORT_BITS(TLCLK_REG0, 0xfc, 2);
                                break;
                        case CLK_11_184MHz:
                                SET_PORT_BITS(TLCLK_REG0, 0xfc, 0);
@@ -549,7 +559,7 @@ static ssize_t store_select_amcb1_transmit_clock(struct device *d,
                                SET_PORT_BITS(TLCLK_REG0, 0xfc, 3);
                                break;
                        case CLK_44_736MHz:
-                               SET_PORT_BITS(TLCLK_REG0, 0xfc, 2);
+                               SET_PORT_BITS(TLCLK_REG0, 0xfc, 1);
                                break;
                        }
                } else
@@ -839,11 +849,13 @@ static void __exit tlclk_cleanup(void)
 
 static void switchover_timeout(unsigned long data)
 {
-       if ((data & 1)) {
-               if ((inb(TLCLK_REG1) & 0x08) != (data & 0x08))
+       unsigned long flags = *(unsigned long *) data;
+
+       if ((flags & 1)) {
+               if ((inb(TLCLK_REG1) & 0x08) != (flags & 0x08))
                        alarm_events->switchover_primary++;
        } else {
-               if ((inb(TLCLK_REG1) & 0x08) != (data & 0x08))
+               if ((inb(TLCLK_REG1) & 0x08) != (flags & 0x08))
                        alarm_events->switchover_secondary++;
        }
 
@@ -901,8 +913,9 @@ static irqreturn_t tlclk_interrupt(int irq, void *dev_id)
 
                /* TIMEOUT in ~10ms */
                switchover_timer.expires = jiffies + msecs_to_jiffies(10);
-               switchover_timer.data = inb(TLCLK_REG1);
-               add_timer(&switchover_timer);
+               tlclk_timer_data = inb(TLCLK_REG1);
+               switchover_timer.data = (unsigned long) &tlclk_timer_data;
+               mod_timer(&switchover_timer, switchover_timer.expires);
        } else {
                got_event = 1;
                wake_up(&wq);