On Tue, Jul 11, 2006 at 09:45:41AM +0200, Ingo Molnar wrote:
[Apologies for the very slow turn-around time on this. If patches
are written in the relatively-near future, I will test and report in a
more timely manner.]
> Subject: lockdep: HPET/RTC fix
> From: Ingo Molnar <[email protected]>
>
> Joseph Fannin reported that hpet_rtc_interrupt() enables hardirqs
> in irq context:
> --- linux.orig/drivers/char/rtc.c
> +++ linux/drivers/char/rtc.c
> @@ -1222,7 +1222,7 @@ static int rtc_proc_open(struct inode *i
>
> 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;
> @@ -1249,7 +1249,7 @@ void rtc_get_rtc_time(struct rtc_time *r
> * 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);
> @@ -1263,7 +1263,7 @@ void rtc_get_rtc_time(struct rtc_time *r
> 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)
> {
It seems this isn't enough:
[ 22.504000] EXT3 FS on sda3, internal journal
[ 22.892000] BUG: warning at kernel/lockdep.c:1803/trace_hardirqs_on()
[ 22.892000] [<c0104880>] show_trace_log_lvl+0x1a0/0x1d0
[ 22.892000] [<c0105a7b>] show_trace+0x1b/0x20
[ 22.892000] [<c0105aa4>] dump_stack+0x24/0x30
[ 22.892000] [<c01451e4>] trace_hardirqs_on+0xf4/0x180
[ 22.892000] [<c032e431>] _spin_unlock_irq+0x31/0x60
[ 22.892000] [<c0278a64>] rtc_get_rtc_time+0x44/0x1a0
[ 22.892000] [<c0118742>] hpet_rtc_interrupt+0x152/0x1b0
[ 22.892000] [<c015bb51>] handle_IRQ_event+0x31/0x70
[ 22.892000] [<c015bc29>] __do_IRQ+0x99/0x110
[ 22.892000] [<c0105ef7>] do_IRQ+0x47/0xa0
[ 22.892000] [<c0103eed>] common_interrupt+0x25/0x2c
[ 22.892000] [<c032f902>] do_page_fault+0x82/0x630
[ 22.892000] [<c0104085>] error_code+0x39/0x40
[ 22.892000] [<b7e8d060>] 0xb7e8d060
[ 22.892000] [<c0105a7b>] show_trace+0x1b/0x20
[ 22.892000] [<c0105aa4>] dump_stack+0x24/0x30
[ 22.892000] [<c01451e4>] trace_hardirqs_on+0xf4/0x180
[ 22.892000] [<c032e431>] _spin_unlock_irq+0x31/0x60
[ 22.892000] [<c0278a64>] rtc_get_rtc_time+0x44/0x1a0
[ 22.892000] [<c0118742>] hpet_rtc_interrupt+0x152/0x1b0
[ 22.892000] [<c015bb51>] handle_IRQ_event+0x31/0x70
[ 22.892000] [<c015bc29>] __do_IRQ+0x99/0x110
[ 22.892000] [<c0105ef7>] do_IRQ+0x47/0xa0
[ 22.892000] [<c0103eed>] common_interrupt+0x25/0x2c
[ 22.892000] [<c0104085>] error_code+0x39/0x40
This is from 2.6.18-rc3, but it's reproducable with pretty much
any kernel (the -rc3 backtrace is longer, it seems).
Should I file this in Bugzilla?
--
Joseph Fannin
[email protected]