[WATCHDOG] wdt: fix locking
The audit of _p usage shows various drivers assume inb_p is somehow atomic.
Of course it isn't and the delay can be split from the I/O cycle causing a
timing violation on chips that matter (eg this one)
With the proposed use of udelay() for some _p delays this will cease to be
a mostly theoretical bug (as the delay stall is unsplittable) and wants
fixing.
Lots of other drivers need fixing this way too.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/drivers/watchdog/wdt.c b/drivers/watchdog/wdt.c
index 53d0bb4..756fb15 100644
--- a/drivers/watchdog/wdt.c
+++ b/drivers/watchdog/wdt.c
@@ -70,6 +70,8 @@
static int io=0x240;
static int irq=11;
+static DEFINE_SPINLOCK(wdt_lock);
+
module_param(io, int, 0);
MODULE_PARM_DESC(io, "WDT io port (default=0x240)");
module_param(irq, int, 0);
@@ -109,6 +111,8 @@
static int wdt_start(void)
{
+ unsigned long flags;
+ spin_lock_irqsave(&wdt_lock, flags);
inb_p(WDT_DC); /* Disable watchdog */
wdt_ctr_mode(0,3); /* Program CTR0 for Mode 3: Square Wave Generator */
wdt_ctr_mode(1,2); /* Program CTR1 for Mode 2: Rate Generator */
@@ -117,6 +121,7 @@
wdt_ctr_load(1,wd_heartbeat); /* Heartbeat */
wdt_ctr_load(2,65535); /* Length of reset pulse */
outb_p(0, WDT_DC); /* Enable watchdog */
+ spin_unlock_irqrestore(&wdt_lock, flags);
return 0;
}
@@ -128,9 +133,12 @@
static int wdt_stop (void)
{
+ unsigned long flags;
+ spin_lock_irqsave(&wdt_lock, flags);
/* Turn the card off */
inb_p(WDT_DC); /* Disable watchdog */
wdt_ctr_load(2,0); /* 0 length reset pulses now */
+ spin_unlock_irqrestore(&wdt_lock, flags);
return 0;
}
@@ -143,11 +151,14 @@
static int wdt_ping(void)
{
+ unsigned long flags;
+ spin_lock_irqsave(&wdt_lock, flags);
/* Write a watchdog value */
inb_p(WDT_DC); /* Disable watchdog */
wdt_ctr_mode(1,2); /* Re-Program CTR1 for Mode 2: Rate Generator */
wdt_ctr_load(1,wd_heartbeat); /* Heartbeat */
outb_p(0, WDT_DC); /* Enable watchdog */
+ spin_unlock_irqrestore(&wdt_lock, flags);
return 0;
}
@@ -182,7 +193,12 @@
static int wdt_get_status(int *status)
{
- unsigned char new_status=inb_p(WDT_SR);
+ unsigned char new_status;
+ unsigned long flags;
+
+ spin_lock_irqsave(&wdt_lock, flags);
+ new_status = inb_p(WDT_SR);
+ spin_unlock_irqrestore(&wdt_lock, flags);
*status=0;
if (new_status & WDC_SR_ISOI0)
@@ -214,8 +230,12 @@
static int wdt_get_temperature(int *temperature)
{
- unsigned short c=inb_p(WDT_RT);
+ unsigned short c;
+ unsigned long flags;
+ spin_lock_irqsave(&wdt_lock, flags);
+ c = inb_p(WDT_RT);
+ spin_unlock_irqrestore(&wdt_lock, flags);
*temperature = (c * 11 / 15) + 7;
return 0;
}
@@ -237,7 +257,10 @@
* Read the status register see what is up and
* then printk it.
*/
- unsigned char status=inb_p(WDT_SR);
+ unsigned char status;
+
+ spin_lock(&wdt_lock);
+ status = inb_p(WDT_SR);
printk(KERN_CRIT "WDT status %d\n", status);
@@ -265,6 +288,7 @@
printk(KERN_CRIT "Reset in 5ms.\n");
#endif
}
+ spin_unlock(&wdt_lock);
return IRQ_HANDLED;
}