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Commit 760928c0 authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Ingo Molnar
Browse files

locking/spinlocks, s390: Implement vcpu_is_preempted(cpu) 



This implements the s390 version for vcpu_is_preempted(cpu),
by reworking the existing smp_vcpu_scheduled() function into
arch_vcpu_is_preempted().

We can then also get rid of the local cpu_is_preempted()
function by moving the CIF_ENABLED_WAIT test into
arch_vcpu_is_preempted().

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: boqun.feng@gmail.com
Cc: bsingharora@gmail.com
Cc: dave@stgolabs.net
Cc: jgross@suse.com
Cc: kernellwp@gmail.com
Cc: konrad.wilk@oracle.com
Cc: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au
Cc: paulmck@linux.vnet.ibm.com
Cc: paulus@samba.org
Cc: pbonzini@redhat.com
Cc: rkrcmar@redhat.com
Cc: virtualization@lists.linux-foundation.org
Cc: will.deacon@arm.com
Cc: xen-devel-request@lists.xenproject.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1478077718-37424-6-git-send-email-xinhui.pan@linux.vnet.ibm.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 41946c86

arch/s390/include/asm/spinlock.h

+8 −0
Original line number Diff line number Diff line
@@ -23,6 +23,14 @@ _raw_compare_and_swap(unsigned int *lock, unsigned int old, unsigned int new) 
	return __sync_bool_compare_and_swap(lock, old, new);

}



#ifndef CONFIG_SMP

static inline bool arch_vcpu_is_preempted(int cpu) { return false; }

#else

bool arch_vcpu_is_preempted(int cpu);

#endif



#define vcpu_is_preempted arch_vcpu_is_preempted



/*

 * Simple spin lock operations.  There are two variants, one clears IRQ's

 * on the local processor, one does not.

arch/s390/kernel/smp.c

+7 −2
Original line number Diff line number Diff line
@@ -368,10 +368,15 @@ int smp_find_processor_id(u16 address) 
	return -1;

}



int smp_vcpu_scheduled(int cpu)

bool arch_vcpu_is_preempted(int cpu)

{

	return pcpu_running(pcpu_devices + cpu);

	if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu))

		return false;

	if (pcpu_running(pcpu_devices + cpu))

		return false;

	return true;

}

EXPORT_SYMBOL(arch_vcpu_is_preempted);



void smp_yield_cpu(int cpu)

{

arch/s390/lib/spinlock.c

+8 −17
Original line number Diff line number Diff line
@@ -37,15 +37,6 @@ static inline void _raw_compare_and_delay(unsigned int *lock, unsigned int old) 
	asm(".insn rsy,0xeb0000000022,%0,0,%1" : : "d" (old), "Q" (*lock));

}



static inline int cpu_is_preempted(int cpu)

{

	if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu))

		return 0;

	if (smp_vcpu_scheduled(cpu))

		return 0;

	return 1;

}



void arch_spin_lock_wait(arch_spinlock_t *lp)

{

	unsigned int cpu = SPINLOCK_LOCKVAL;
@@ -62,7 +53,7 @@ void arch_spin_lock_wait(arch_spinlock_t *lp) 
			continue;

		}

		/* First iteration: check if the lock owner is running. */

		if (first_diag && cpu_is_preempted(~owner)) {

		if (first_diag && arch_vcpu_is_preempted(~owner)) {

			smp_yield_cpu(~owner);

			first_diag = 0;

			continue;
@@ -81,7 +72,7 @@ void arch_spin_lock_wait(arch_spinlock_t *lp) 
		 * yield the CPU unconditionally. For LPAR rely on the

		 * sense running status.

		 */

		if (!MACHINE_IS_LPAR || cpu_is_preempted(~owner)) {

		if (!MACHINE_IS_LPAR || arch_vcpu_is_preempted(~owner)) {

			smp_yield_cpu(~owner);

			first_diag = 0;

		}
@@ -108,7 +99,7 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags) 
			continue;

		}

		/* Check if the lock owner is running. */

		if (first_diag && cpu_is_preempted(~owner)) {

		if (first_diag && arch_vcpu_is_preempted(~owner)) {

			smp_yield_cpu(~owner);

			first_diag = 0;

			continue;
@@ -127,7 +118,7 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags) 
		 * yield the CPU unconditionally. For LPAR rely on the

		 * sense running status.

		 */

		if (!MACHINE_IS_LPAR || cpu_is_preempted(~owner)) {

		if (!MACHINE_IS_LPAR || arch_vcpu_is_preempted(~owner)) {

			smp_yield_cpu(~owner);

			first_diag = 0;

		}
@@ -165,7 +156,7 @@ void _raw_read_lock_wait(arch_rwlock_t *rw) 
	owner = 0;

	while (1) {

		if (count-- <= 0) {

			if (owner && cpu_is_preempted(~owner))

			if (owner && arch_vcpu_is_preempted(~owner))

				smp_yield_cpu(~owner);

			count = spin_retry;

		}
@@ -211,7 +202,7 @@ void _raw_write_lock_wait(arch_rwlock_t *rw, unsigned int prev) 
	owner = 0;

	while (1) {

		if (count-- <= 0) {

			if (owner && cpu_is_preempted(~owner))

			if (owner && arch_vcpu_is_preempted(~owner))

				smp_yield_cpu(~owner);

			count = spin_retry;

		}
@@ -241,7 +232,7 @@ void _raw_write_lock_wait(arch_rwlock_t *rw) 
	owner = 0;

	while (1) {

		if (count-- <= 0) {

			if (owner && cpu_is_preempted(~owner))

			if (owner && arch_vcpu_is_preempted(~owner))

				smp_yield_cpu(~owner);

			count = spin_retry;

		}
@@ -285,7 +276,7 @@ void arch_lock_relax(unsigned int cpu) 
{

	if (!cpu)

		return;

	if (MACHINE_IS_LPAR && !cpu_is_preempted(~cpu))

	if (MACHINE_IS_LPAR && !arch_vcpu_is_preempted(~cpu))

		return;

	smp_yield_cpu(~cpu);

}