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Commit 01c785dc authored by Alan Cox's avatar Alan Cox Committed by Wim Van Sebroeck
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[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: default avatarAlan Cox <alan@redhat.com>
Signed-off-by: default avatarWim Van Sebroeck <wim@iguana.be>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b47711bf

drivers/watchdog/wdt.c

+27 −3
Original line number Diff line number Diff line
@@ -70,6 +70,8 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" _ 
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 void wdt_ctr_load(int ctr, int val) 


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 @@ static int wdt_start(void) 
	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_start(void) 


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_stop (void) 


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_set_heartbeat(int t) 


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_status(int *status) 


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 @@ static irqreturn_t wdt_interrupt(int irq, void *dev_id) 
	 *	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 @@ static irqreturn_t wdt_interrupt(int irq, void *dev_id) 
		printk(KERN_CRIT "Reset in 5ms.\n");

#endif

	}

	spin_unlock(&wdt_lock);

	return IRQ_HANDLED;

}