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Commit 0f749646 authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
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[PATCH] lockdep: HPET/RTC fix 



Joseph Fannin reported that hpet_rtc_interrupt() enables hardirqs
in irq context:

[   25.628000]  [<c014af4e>] trace_hardirqs_on+0xce/0x200
[   25.628000]  [<c036cf21>] _spin_unlock_irq+0x31/0x70
[   25.628000]  [<c0296584>] rtc_get_rtc_time+0x44/0x1a0
[   25.628000]  [<c01198bb>] hpet_rtc_interrupt+0x21b/0x280
[   25.628000]  [<c0161141>] handle_IRQ_event+0x31/0x70
[   25.628000]  [<c0162d37>] handle_edge_irq+0xe7/0x210
[   25.628000]  [<c0106192>] do_IRQ+0x92/0x120
[   25.628000]  [<c0104121>] common_interrupt+0x25/0x2c

the call of rtc_get_rtc_time() is highly suspect. At a minimum we
need the patch below to save/restore hardirq state.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Cc: Joseph Fannin <jfannin@gmail.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent a29b0b74

drivers/char/rtc.c

+3 −3
Original line number Diff line number Diff line
@@ -1245,7 +1245,7 @@ static int rtc_proc_open(struct inode *inode, struct file *file) 


void rtc_get_rtc_time(struct rtc_time *rtc_tm)

{

	unsigned long uip_watchdog = jiffies;

	unsigned long uip_watchdog = jiffies, flags;

	unsigned char ctrl;

#ifdef CONFIG_MACH_DECSTATION

	unsigned int real_year;
@@ -1272,7 +1272,7 @@ void rtc_get_rtc_time(struct rtc_time *rtc_tm) 
	 * RTC has RTC_DAY_OF_WEEK, we should usually ignore it, as it is

	 * only updated by the RTC when initially set to a non-zero value.

	 */

	spin_lock_irq(&rtc_lock);

	spin_lock_irqsave(&rtc_lock, flags);

	rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);

	rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);

	rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
@@ -1286,7 +1286,7 @@ void rtc_get_rtc_time(struct rtc_time *rtc_tm) 
	real_year = CMOS_READ(RTC_DEC_YEAR);

#endif

	ctrl = CMOS_READ(RTC_CONTROL);

	spin_unlock_irq(&rtc_lock);

	spin_unlock_irqrestore(&rtc_lock, flags);



	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)

	{