From d3d238c7744d08c36a114a59cb537d4c0c6c9a86 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 3 Oct 2008 21:54:59 +0200 Subject: [S390] nohz: Fix __udelay. This fixes a regression that came with 934b2857cc576ae53c92a66e63fce7ddcfa74691 ("[S390] nohz/sclp: disable timer on synchronous waits."). If udelay() gets called from a disabled context it sets the clock comparator to a value where it expects the next interrupt. When the interrupt happens the clock comparator gets not reset and therefore the interrupt condition doesn't get cleared. The result is an endless timer interrupt loop. In addition this patch fixes also the following: rcutorture reveals that our __udelay implementation is still buggy, since it might schedule tasklets, but prevents their execution: NOHZ: local_softirq_pending 42 NOHZ: local_softirq_pending 02 NOHZ: local_softirq_pending 142 NOHZ: local_softirq_pending 02 To fix this we make sure that only the clock comparator interrupt is enabled when the enabled wait psw is loaded. Also no code gets called anymore which might schedule tasklets. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/time.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/s390/kernel/time.c') diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index ca114fe46ffb..06acb1a18bbc 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -169,6 +169,8 @@ void init_cpu_timer(void) static void clock_comparator_interrupt(__u16 code) { + if (S390_lowcore.clock_comparator == -1ULL) + set_clock_comparator(S390_lowcore.clock_comparator); } static void etr_timing_alert(struct etr_irq_parm *); -- cgit v1.2.3 From 4a672cfa3a7fcbc6f2adc558f34148be1096c561 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Fri, 10 Oct 2008 21:33:29 +0200 Subject: [S390] fix initialization of stp chsc_sstpc returns -EIO on error and 0 on success but stp_reset checks against 1 instead of 0. chsc_sstpc used to return 1 on success, one call location has not been updated .. Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/time.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/s390/kernel/time.c') diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index 06acb1a18bbc..b94e9e3b694a 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -1356,7 +1356,7 @@ static void __init stp_reset(void) stp_page = alloc_bootmem_pages(PAGE_SIZE); rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000); - if (rc == 1) + if (rc == 0) set_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags); else if (stp_online) { printk(KERN_WARNING "Running on non STP capable machine.\n"); -- cgit v1.2.3