[Xen-devel] [PATCH v6 05/11] s390/spinlock: Provide vcpu_is_preempted

[Pan Xinhui <xinhui.pan@xxxxxxxxxxxxxxxxxx>]

From: Christian Borntraeger <borntraeger@xxxxxxxxxx>

this implements the s390 backend for commit
"kernel/sched: introduce vcpu preempted check interface"
by reworking the existing smp_vcpu_scheduled 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: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Acked-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
---
 arch/s390/include/asm/spinlock.h |  8 ++++++++
 arch/s390/kernel/smp.c           |  9 +++++++--
 arch/s390/lib/spinlock.c         | 25 ++++++++-----------------
 3 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/arch/s390/include/asm/spinlock.h b/arch/s390/include/asm/spinlock.h
index 7e9e09f..7ecd890 100644
--- a/arch/s390/include/asm/spinlock.h
+++ b/arch/s390/include/asm/spinlock.h
@@ -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.
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 35531fe..b988ed1 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -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)
 {
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c
index e5f50a7..e48a48e 100644
--- a/arch/s390/lib/spinlock.c
+++ b/arch/s390/lib/spinlock.c
@@ -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);
 }
-- 
2.4.11


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