From: Christian Borntraeger Date: Tue, 6 Oct 2009 08:34:04 +0000 (+0200) Subject: [S390] Fix enabled udelay for short delays. X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=78d81f2f844b739b377817cfd279fb6067e191a7;p=deliverable%2Flinux.git [S390] Fix enabled udelay for short delays. When udelay() gets called with a delay that would expire before the next clock event it reprograms the clock comparator. When the interrupt happens the clock comparator won't be resetted therefore the interrupt condition doesn't get cleared. The result is an endless timer interrupt loop until the next clock event would expire (stored in lowcore). So udelay() usually would wait much longer for small delays than it should. Fix this by disabling the local tick which makes sure that the clock comparator will be resetted when a timer interrupt happens. Signed-off-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky --- diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c index 97c1eca83cc2..2c3094342789 100644 --- a/arch/s390/lib/delay.c +++ b/arch/s390/lib/delay.c @@ -49,17 +49,22 @@ static void __udelay_disabled(unsigned long usecs) static void __udelay_enabled(unsigned long usecs) { unsigned long mask; - u64 end, time; + u64 clock_saved; + u64 end; mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT | PSW_MASK_IO; end = get_clock() + ((u64) usecs << 12); do { - time = end < S390_lowcore.clock_comparator ? - end : S390_lowcore.clock_comparator; - set_clock_comparator(time); + clock_saved = 0; + if (end < S390_lowcore.clock_comparator) { + clock_saved = local_tick_disable(); + set_clock_comparator(end); + } trace_hardirqs_on(); __load_psw_mask(mask); local_irq_disable(); + if (clock_saved) + local_tick_enable(clock_saved); } while (get_clock() < end); set_clock_comparator(S390_lowcore.clock_comparator); }