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Commit 934b2857 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
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[S390] nohz/sclp: disable timer on synchronous waits. 



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: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 3a95e8eb

arch/s390/lib/delay.c

+2 −2
Original line number Diff line number Diff line
@@ -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();

drivers/s390/char/sclp.c

+4 −2
Original line number Diff line number Diff line
@@ -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. */

include/asm-s390/hardirq.h

+14 −0
Original line number Diff line number Diff line
@@ -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 */