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authorLinus Torvalds <torvalds@linux-foundation.org>2015-09-18 09:23:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-18 09:23:08 -0700
commit3ae839454e77cdc87d499a4bfd0932dec5763b55 (patch)
treece4c99f05beabdd02cdf604beb2bb0c3f912d201 /kernel
parentfadb97b089563da69ba326f9fea6399d071462b2 (diff)
parent00cc1633816de8c95f337608a1ea64e228faf771 (diff)
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM fixes from Paolo Bonzini: "Mostly stable material, a lot of ARM fixes" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (22 commits) sched: access local runqueue directly in single_task_running arm/arm64: KVM: Remove 'config KVM_ARM_MAX_VCPUS' arm64: KVM: Remove all traces of the ThumbEE registers arm: KVM: Disable virtual timer even if the guest is not using it arm64: KVM: Disable virtual timer even if the guest is not using it arm/arm64: KVM: vgic: Check for !irqchip_in_kernel() when mapping resources KVM: s390: Replace incorrect atomic_or with atomic_andnot arm: KVM: Fix incorrect device to IPA mapping arm64: KVM: Fix user access for debug registers KVM: vmx: fix VPID is 0000H in non-root operation KVM: add halt_attempted_poll to VCPU stats kvm: fix zero length mmio searching kvm: fix double free for fast mmio eventfd kvm: factor out core eventfd assign/deassign logic kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd KVM: make the declaration of functions within 80 characters KVM: arm64: add workaround for Cortex-A57 erratum #852523 KVM: fix polling for guest halt continued even if disable it arm/arm64: KVM: Fix PSCI affinity info return value for non valid cores arm64: KVM: set {v,}TCR_EL2 RES1 bits ...
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c15
1 files changed, 11 insertions, 4 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 97d276ff1edb..2f9c92884817 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2669,13 +2669,20 @@ unsigned long nr_running(void)
/*
* Check if only the current task is running on the cpu.
+ *
+ * Caution: this function does not check that the caller has disabled
+ * preemption, thus the result might have a time-of-check-to-time-of-use
+ * race. The caller is responsible to use it correctly, for example:
+ *
+ * - from a non-preemptable section (of course)
+ *
+ * - from a thread that is bound to a single CPU
+ *
+ * - in a loop with very short iterations (e.g. a polling loop)
*/
bool single_task_running(void)
{
- if (cpu_rq(smp_processor_id())->nr_running == 1)
- return true;
- else
- return false;
+ return raw_rq()->nr_running == 1;
}
EXPORT_SYMBOL(single_task_running);