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authorHeiko Carstens <heiko.carstens@de.ibm.com>2008-10-03 15:54:59 -0400
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2008-10-03 15:55:54 -0400
commitd3d238c7744d08c36a114a59cb537d4c0c6c9a86 (patch)
treedf5d69d40dbdaf5e5014a6ce41909e7236a196c1 /arch/s390/kernel
parent95b866d5afcafee00fc9ad70665e48c86d8c4e0f (diff)
[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 <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel')
-rw-r--r--arch/s390/kernel/time.c2
1 files changed, 2 insertions, 0 deletions
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)
169 169
170static void clock_comparator_interrupt(__u16 code) 170static void clock_comparator_interrupt(__u16 code)
171{ 171{
172 if (S390_lowcore.clock_comparator == -1ULL)
173 set_clock_comparator(S390_lowcore.clock_comparator);
172} 174}
173 175
174static void etr_timing_alert(struct etr_irq_parm *); 176static void etr_timing_alert(struct etr_irq_parm *);