A repeatable but randomly timed freeze has been happening in Fedora 6 and 7 for the last year, whenever I run the ntpd service on my AMD64x2 HP Pavilion dv9000z laptop. This freeze is due to the use of spin_lock(&rtc_lock) under the assumption (per a bad comment) that set_rtc_mmss is called only with interrupts disabled. The call from ntp.c to update_persistent_clock is made with interrupts enabled. Signed-off-by: David P. Reed <[email protected]> --- I have thoroughly tested this patch on a number of x86_64 machines with various numbers of cores and chipsets, using 2.6.24rc2 kernel source. Index: linux-2.6/arch/x86/kernel/time_64.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/time_64.c +++ linux-2.6/arch/x86/kernel/time_64.c @@ -82,18 +82,15 @@ static int set_rtc_mmss(unsigned long no int retval = 0; int real_seconds, real_minutes, cmos_minutes; unsigned char control, freq_select; + unsigned long flags; /* - * IRQs are disabled when we're called from the timer interrupt, - * no need for spin_lock_irqsave() + * set_rtc_mmss is called when irqs are enabled, so disable irqs here */ - - spin_lock(&rtc_lock); - + spin_lock_irqsave(&rtc_lock, flags); /* * Tell the clock it's being set and stop it. */ - control = CMOS_READ(RTC_CONTROL); CMOS_WRITE(control | RTC_SET, RTC_CONTROL); @@ -138,7 +135,7 @@ static int set_rtc_mmss(unsigned long no CMOS_WRITE(control, RTC_CONTROL); CMOS_WRITE(freq_select, RTC_FREQ_SELECT); - spin_unlock(&rtc_lock); + spin_unlock_irqrestore(&rtc_lock, flags); return retval; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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