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[S390] nohz/sclp: disable timer on synchronous waits.

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sclp_sync_wait wait synchronously for an sclp interrupt and disables
timer interrupts. However on the irq enter paths there is an extra
check if a timer interrupt would be due and calls the timer callback.
This would schedule softirqs in the wrong context.
So introduce local_tick_enable/disable which prevents this.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2008-08-01 16:39:11 +02:00 committed by Martin Schwidefsky
parent 3a95e8eb34
commit 934b2857cc
3 changed files with 20 additions and 4 deletions
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4
arch/s390/lib/delay.c
View file

@ -43,7 +43,7 @@ void __udelay(unsigned long usecs)
local_bh_disable();
local_irq_save(flags);
if (raw_irqs_disabled_flags(flags)) {
old_cc = S390_lowcore.clock_comparator;
old_cc = local_tick_disable();
S390_lowcore.clock_comparator = -1ULL;
__ctl_store(cr0, 0, 0);
dummy = (cr0 & 0xffff00e0) | 0x00000800;
@ -65,7 +65,7 @@ void __udelay(unsigned long usecs)
if (raw_irqs_disabled_flags(flags)) {
__ctl_load(cr0, 0, 0);
S390_lowcore.clock_comparator = old_cc;
local_tick_enable(old_cc);
}
if (!irq_context)
_local_bh_enable();

6
drivers/s390/char/sclp.c
View file

@ -399,6 +399,7 @@ sclp_tod_from_jiffies(unsigned long jiffies)
void
sclp_sync_wait(void)
{
unsigned long long old_tick;
unsigned long flags;
unsigned long cr0, cr0_sync;
u64 timeout;
@ -419,11 +420,12 @@ sclp_sync_wait(void)
if (!irq_context)
local_bh_disable();
/* Enable service-signal interruption, disable timer interrupts */
old_tick = local_tick_disable();
trace_hardirqs_on();
__ctl_store(cr0, 0, 0);
cr0_sync = cr0;
cr0_sync &= 0xffff00a0;
cr0_sync |= 0x00000200;
cr0_sync &= 0xFFFFF3AC;
__ctl_load(cr0_sync, 0, 0);
__raw_local_irq_stosm(0x01);
/* Loop until driver state indicates finished request */
@ -439,9 +441,9 @@ sclp_sync_wait(void)
__ctl_load(cr0, 0, 0);
if (!irq_context)
_local_bh_enable();
local_tick_enable(old_tick);
local_irq_restore(flags);
}
EXPORT_SYMBOL(sclp_sync_wait);
/* Dispatch changes in send and receive mask to registered listeners. */

14
include/asm-s390/hardirq.h
View file

@ -34,4 +34,18 @@ typedef struct {
void clock_comparator_work(void);
static inline unsigned long long local_tick_disable(void)
{
unsigned long long old;
old = S390_lowcore.clock_comparator;
S390_lowcore.clock_comparator = -1ULL;
return old;
}
static inline void local_tick_enable(unsigned long long comp)
{
S390_lowcore.clock_comparator = comp;
}
#endif /* __ASM_HARDIRQ_H */