rtc: lockdep fix/workaround

BUG: warning at kernel/lockdep.c:1816/trace_hardirqs_on() (Not tainted)
 [<c04051ee>] show_trace_log_lvl+0x58/0x171
 [<c0405802>] show_trace+0xd/0x10
 [<c040591b>] dump_stack+0x19/0x1b
 [<c043abee>] trace_hardirqs_on+0xa2/0x11e
 [<c06143c3>] _spin_unlock_irq+0x22/0x26
 [<c0541540>] rtc_get_rtc_time+0x32/0x176
 [<c0419ba4>] hpet_rtc_interrupt+0x92/0x14d
 [<c0450f94>] handle_IRQ_event+0x20/0x4d
 [<c0451055>] __do_IRQ+0x94/0xef
 [<c040678d>] do_IRQ+0x9e/0xbd
 [<c0404a49>] common_interrupt+0x25/0x2c
DWARF2 unwinder stuck at common_interrupt+0x25/0x2c

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

diff --git a/drivers/char/rtc.c b/drivers/char/rtc.c
index 7cac6d05d72353da0c69c883d1806e59cc50aa8e..70e7ec0fef43da6350d522392606b2db2627e887 100644 (file)
--- a/drivers/char/rtc.c
+++ b/drivers/char/rtc.c
@@ -211,11 +211,12 @@ static const unsigned char days_in_mo[] =
  */
 static inline unsigned char rtc_is_updating(void)
 {
+       unsigned long flags;
        unsigned char uip;
 
-       spin_lock_irq(&rtc_lock);
+       spin_lock_irqsave(&rtc_lock, flags);
        uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
-       spin_unlock_irq(&rtc_lock);
+       spin_unlock_irqrestore(&rtc_lock, flags);
        return uip;
 }