diff options
| -rw-r--r-- | arch/s390/include/asm/processor.h | 12 | ||||
| -rw-r--r-- | arch/s390/kernel/entry.S | 2 | ||||
| -rw-r--r-- | arch/s390/lib/spinlock.c | 25 |
3 files changed, 31 insertions, 8 deletions
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h index b16c3d0a1b9f..5592c94ebe31 100644 --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -18,12 +18,14 @@ #define CIF_NOHZ_DELAY 2 /* delay HZ disable for a tick */ #define CIF_FPU 3 /* restore FPU registers */ #define CIF_IGNORE_IRQ 4 /* ignore interrupt (for udelay) */ +#define CIF_ENABLED_WAIT 5 /* in enabled wait state */ #define _CIF_MCCK_PENDING _BITUL(CIF_MCCK_PENDING) #define _CIF_ASCE _BITUL(CIF_ASCE) #define _CIF_NOHZ_DELAY _BITUL(CIF_NOHZ_DELAY) #define _CIF_FPU _BITUL(CIF_FPU) #define _CIF_IGNORE_IRQ _BITUL(CIF_IGNORE_IRQ) +#define _CIF_ENABLED_WAIT _BITUL(CIF_ENABLED_WAIT) #ifndef __ASSEMBLY__ @@ -52,6 +54,16 @@ static inline int test_cpu_flag(int flag) return !!(S390_lowcore.cpu_flags & (1UL << flag)); } +/* + * Test CIF flag of another CPU. The caller needs to ensure that + * CPU hotplug can not happen, e.g. by disabling preemption. + */ +static inline int test_cpu_flag_of(int flag, int cpu) +{ + struct _lowcore *lc = lowcore_ptr[cpu]; + return !!(lc->cpu_flags & (1UL << flag)); +} + #define arch_needs_cpu() test_cpu_flag(CIF_NOHZ_DELAY) /* diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 857b6526d298..cd5a191381b9 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -764,6 +764,7 @@ ENTRY(psw_idle) .insn rsy,0xeb0000000017,%r1,5,__SF_EMPTY+16(%r15) .Lpsw_idle_stcctm: #endif + oi __LC_CPU_FLAGS+7,_CIF_ENABLED_WAIT STCK __CLOCK_IDLE_ENTER(%r2) stpt __TIMER_IDLE_ENTER(%r2) .Lpsw_idle_lpsw: @@ -1146,6 +1147,7 @@ cleanup_critical: .quad .Lio_done - 4 .Lcleanup_idle: + ni __LC_CPU_FLAGS+7,255-_CIF_ENABLED_WAIT # copy interrupt clock & cpu timer mvc __CLOCK_IDLE_EXIT(8,%r2),__LC_INT_CLOCK mvc __TIMER_IDLE_EXIT(8,%r2),__LC_ASYNC_ENTER_TIMER diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c index 0a68fe04a9e1..d4549c964589 100644 --- a/arch/s390/lib/spinlock.c +++ b/arch/s390/lib/spinlock.c @@ -37,6 +37,15 @@ 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; @@ -53,7 +62,7 @@ void arch_spin_lock_wait(arch_spinlock_t *lp) continue; } /* First iteration: check if the lock owner is running. */ - if (first_diag && !smp_vcpu_scheduled(~owner)) { + if (first_diag && cpu_is_preempted(~owner)) { smp_yield_cpu(~owner); first_diag = 0; continue; @@ -72,7 +81,7 @@ 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 || !smp_vcpu_scheduled(~owner)) { + if (!MACHINE_IS_LPAR || cpu_is_preempted(~owner)) { smp_yield_cpu(~owner); first_diag = 0; } @@ -98,7 +107,7 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags) local_irq_restore(flags); } /* Check if the lock owner is running. */ - if (first_diag && !smp_vcpu_scheduled(~owner)) { + if (first_diag && cpu_is_preempted(~owner)) { smp_yield_cpu(~owner); first_diag = 0; continue; @@ -117,7 +126,7 @@ 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 || !smp_vcpu_scheduled(~owner)) { + if (!MACHINE_IS_LPAR || cpu_is_preempted(~owner)) { smp_yield_cpu(~owner); first_diag = 0; } @@ -155,7 +164,7 @@ void _raw_read_lock_wait(arch_rwlock_t *rw) owner = 0; while (1) { if (count-- <= 0) { - if (owner && !smp_vcpu_scheduled(~owner)) + if (owner && cpu_is_preempted(~owner)) smp_yield_cpu(~owner); count = spin_retry; } @@ -201,7 +210,7 @@ void _raw_write_lock_wait(arch_rwlock_t *rw, unsigned int prev) owner = 0; while (1) { if (count-- <= 0) { - if (owner && !smp_vcpu_scheduled(~owner)) + if (owner && cpu_is_preempted(~owner)) smp_yield_cpu(~owner); count = spin_retry; } @@ -231,7 +240,7 @@ void _raw_write_lock_wait(arch_rwlock_t *rw) owner = 0; while (1) { if (count-- <= 0) { - if (owner && !smp_vcpu_scheduled(~owner)) + if (owner && cpu_is_preempted(~owner)) smp_yield_cpu(~owner); count = spin_retry; } @@ -275,7 +284,7 @@ void arch_lock_relax(unsigned int cpu) { if (!cpu) return; - if (MACHINE_IS_LPAR && smp_vcpu_scheduled(~cpu)) + if (MACHINE_IS_LPAR && !cpu_is_preempted(~cpu)) return; smp_yield_cpu(~cpu); } |