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authorGerald Schaefer <gerald.schaefer@de.ibm.com>2010-02-26 22:37:40 +0100
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2010-02-26 22:37:31 +0100
commit59b697874529f5c3cbcaf5816b3d6c584af521e8 (patch)
treec395952c2a0bb9a3027a37a30dd37cc93b1a7c3f /arch/s390/include/asm/smp.h
parent8387c736fcbaec17890b8d075ee4f4623518b54a (diff)
downloadlinux-59b697874529f5c3cbcaf5816b3d6c584af521e8.tar.bz2
[S390] spinlock: check virtual cpu running status
This patch introduces a new function that checks the running status of a cpu in a hypervisor. This status is not virtualized, so the check is only correct if running in an LPAR. On acquiring a spinlock, if the cpu holding the lock is scheduled by the hypervisor, we do a busy wait on the lock. If it is not scheduled, we yield over to that cpu. Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/smp.h')
-rw-r--r--arch/s390/include/asm/smp.h24
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/s390/include/asm/smp.h b/arch/s390/include/asm/smp.h
index c2d0e638f892..edc03cb9cd79 100644
--- a/arch/s390/include/asm/smp.h
+++ b/arch/s390/include/asm/smp.h
@@ -36,6 +36,28 @@ extern void smp_switch_to_cpu(void (*)(void *), void *, unsigned long sp,
int from, int to);
extern void smp_restart_cpu(void);
+/*
+ * returns 1 if (virtual) cpu is scheduled
+ * returns 0 otherwise
+ */
+static inline int smp_vcpu_scheduled(int cpu)
+{
+ u32 status;
+
+ switch (sigp_ps(&status, 0, cpu, sigp_sense_running)) {
+ case sigp_status_stored:
+ /* Check for running status */
+ if (status & 0x400)
+ return 0;
+ break;
+ case sigp_not_operational:
+ return 0;
+ default:
+ break;
+ }
+ return 1;
+}
+
#else /* CONFIG_SMP */
static inline void smp_switch_to_ipl_cpu(void (*func)(void *), void *data)
@@ -43,6 +65,8 @@ static inline void smp_switch_to_ipl_cpu(void (*func)(void *), void *data)
func(data);
}
+#define smp_vcpu_scheduled (1)
+
#endif /* CONFIG_SMP */
#ifdef CONFIG_HOTPLUG_CPU