From: David P. Reed Date: Wed, 14 Nov 2007 22:47:35 +0000 (-0500) Subject: x86: fix freeze in x86_64 RTC update code in time_64.c X-Git-Tag: v2.6.24-rc4~114^2~6 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c399da0d97e06803e51085ec076b63a3168aad1b;p=linux-2.6 x86: fix freeze in x86_64 RTC update code in time_64.c Fix hard freeze on x86_64 when the ntpd service calls update_persistent_clock() 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 Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/kernel/time_64.c b/arch/x86/kernel/time_64.c index c821edc322..4ad1f7a6a8 100644 --- a/arch/x86/kernel/time_64.c +++ b/arch/x86/kernel/time_64.c @@ -82,18 +82,15 @@ static int set_rtc_mmss(unsigned long nowtime) 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 nowtime) CMOS_WRITE(control, RTC_CONTROL); CMOS_WRITE(freq_select, RTC_FREQ_SELECT); - spin_unlock(&rtc_lock); + spin_unlock_irqrestore(&rtc_lock, flags); return retval; }