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Commit c3348760 authored by Takashi Iwai's avatar Takashi Iwai Committed by Jaroslav Kysela
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[PATCH] Fix wrong irq enable via rtc_control() 



rtc_control() may be called in the interrupt context in ALSA rtc-timer
driver.  The patch fixes the wrong irq enable in rtc.c, and also fixes
the possible race of bit flags.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 1d4ae4a1

drivers/char/rtc.c

+38 −27
Original line number Diff line number Diff line
@@ -149,8 +149,22 @@ static void get_rtc_alm_time (struct rtc_time *alm_tm); 
#ifdef RTC_IRQ

static void rtc_dropped_irq(unsigned long data);



static void set_rtc_irq_bit(unsigned char bit);

static void mask_rtc_irq_bit(unsigned char bit);

static void set_rtc_irq_bit_locked(unsigned char bit);

static void mask_rtc_irq_bit_locked(unsigned char bit);



static inline void set_rtc_irq_bit(unsigned char bit)

{

	spin_lock_irq(&rtc_lock);

	set_rtc_irq_bit_locked(bit);

	spin_unlock_irq(&rtc_lock);

}



static void mask_rtc_irq_bit(unsigned char bit)

{

	spin_lock_irq(&rtc_lock);

	mask_rtc_irq_bit_locked(bit);

	spin_unlock_irq(&rtc_lock);

}

#endif



static int rtc_proc_open(struct inode *inode, struct file *file);
@@ -401,18 +415,19 @@ static int rtc_do_ioctl(unsigned int cmd, unsigned long arg, int kernel) 
	}

	case RTC_PIE_OFF:	/* Mask periodic int. enab. bit	*/

	{

		mask_rtc_irq_bit(RTC_PIE);

		unsigned long flags; /* can be called from isr via rtc_control() */

		spin_lock_irqsave (&rtc_lock, flags);

		mask_rtc_irq_bit_locked(RTC_PIE);

		if (rtc_status & RTC_TIMER_ON) {

			spin_lock_irq (&rtc_lock);

			rtc_status &= ~RTC_TIMER_ON;

			del_timer(&rtc_irq_timer);

			spin_unlock_irq (&rtc_lock);

		}

		spin_unlock_irqrestore (&rtc_lock, flags);

		return 0;

	}

	case RTC_PIE_ON:	/* Allow periodic ints		*/

	{



		unsigned long flags; /* can be called from isr via rtc_control() */

		/*

		 * We don't really want Joe User enabling more

		 * than 64Hz of interrupts on a multi-user machine.
@@ -421,14 +436,14 @@ static int rtc_do_ioctl(unsigned int cmd, unsigned long arg, int kernel) 
			(!capable(CAP_SYS_RESOURCE)))

			return -EACCES;



		spin_lock_irqsave (&rtc_lock, flags);

		if (!(rtc_status & RTC_TIMER_ON)) {

			spin_lock_irq (&rtc_lock);

			rtc_irq_timer.expires = jiffies + HZ/rtc_freq + 2*HZ/100;

			add_timer(&rtc_irq_timer);

			rtc_status |= RTC_TIMER_ON;

			spin_unlock_irq (&rtc_lock);

		}

		set_rtc_irq_bit(RTC_PIE);

		set_rtc_irq_bit_locked(RTC_PIE);

		spin_unlock_irqrestore (&rtc_lock, flags);

		return 0;

	}

	case RTC_UIE_OFF:	/* Mask ints from RTC updates.	*/
@@ -609,6 +624,7 @@ static int rtc_do_ioctl(unsigned int cmd, unsigned long arg, int kernel) 
	{

		int tmp = 0;

		unsigned char val;

		unsigned long flags; /* can be called from isr via rtc_control() */



		/* 

		 * The max we can do is 8192Hz.
@@ -631,9 +647,9 @@ static int rtc_do_ioctl(unsigned int cmd, unsigned long arg, int kernel) 
		if (arg != (1<<tmp))

			return -EINVAL;



		spin_lock_irq(&rtc_lock);

		spin_lock_irqsave(&rtc_lock, flags);

		if (hpet_set_periodic_freq(arg)) {

			spin_unlock_irq(&rtc_lock);

			spin_unlock_irqrestore(&rtc_lock, flags);

			return 0;

		}

		rtc_freq = arg;
@@ -641,7 +657,7 @@ static int rtc_do_ioctl(unsigned int cmd, unsigned long arg, int kernel) 
		val = CMOS_READ(RTC_FREQ_SELECT) & 0xf0;

		val |= (16 - tmp);

		CMOS_WRITE(val, RTC_FREQ_SELECT);

		spin_unlock_irq(&rtc_lock);

		spin_unlock_irqrestore(&rtc_lock, flags);

		return 0;

	}

#endif
@@ -844,12 +860,15 @@ int rtc_control(rtc_task_t *task, unsigned int cmd, unsigned long arg) 
#ifndef RTC_IRQ

	return -EIO;

#else

	spin_lock_irq(&rtc_task_lock);

	unsigned long flags;

	if (cmd != RTC_PIE_ON && cmd != RTC_PIE_OFF && cmd != RTC_IRQP_SET)

		return -EINVAL;

	spin_lock_irqsave(&rtc_task_lock, flags);

	if (rtc_callback != task) {

		spin_unlock_irq(&rtc_task_lock);

		spin_unlock_irqrestore(&rtc_task_lock, flags);

		return -ENXIO;

	}

	spin_unlock_irq(&rtc_task_lock);

	spin_unlock_irqrestore(&rtc_task_lock, flags);

	return rtc_do_ioctl(cmd, arg, 1);

#endif

}
@@ -1306,40 +1325,32 @@ static void get_rtc_alm_time(struct rtc_time *alm_tm) 
 * meddles with the interrupt enable/disable bits.

 */



static void mask_rtc_irq_bit(unsigned char bit)

static void mask_rtc_irq_bit_locked(unsigned char bit)

{

	unsigned char val;



	spin_lock_irq(&rtc_lock);

	if (hpet_mask_rtc_irq_bit(bit)) {

		spin_unlock_irq(&rtc_lock);

	if (hpet_mask_rtc_irq_bit(bit))

		return;

	}

	val = CMOS_READ(RTC_CONTROL);

	val &=  ~bit;

	CMOS_WRITE(val, RTC_CONTROL);

	CMOS_READ(RTC_INTR_FLAGS);



	rtc_irq_data = 0;

	spin_unlock_irq(&rtc_lock);

}



static void set_rtc_irq_bit(unsigned char bit)

static void set_rtc_irq_bit_locked(unsigned char bit)

{

	unsigned char val;



	spin_lock_irq(&rtc_lock);

	if (hpet_set_rtc_irq_bit(bit)) {

		spin_unlock_irq(&rtc_lock);

	if (hpet_set_rtc_irq_bit(bit))

		return;

	}

	val = CMOS_READ(RTC_CONTROL);

	val |= bit;

	CMOS_WRITE(val, RTC_CONTROL);

	CMOS_READ(RTC_INTR_FLAGS);



	rtc_irq_data = 0;

	spin_unlock_irq(&rtc_lock);

}

#endif