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author | Linus Torvalds <torvalds@linux-foundation.org> | 2013-02-24 21:07:18 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-02-24 21:07:18 (GMT) |
commit | 89f883372fa60f604d136924baf3e89ff1870e9e (patch) | |
tree | cb69b0a14957945ba00d3d392bf9ccbbef56f3b8 /kernel/sched | |
parent | 9e2d59ad580d590134285f361a0e80f0e98c0207 (diff) | |
parent | 6b73a96065e89dc9fa75ba4f78b1aa3a3bbd0470 (diff) | |
download | linux-fsl-qoriq-89f883372fa60f604d136924baf3e89ff1870e9e.tar.xz |
Merge tag 'kvm-3.9-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Marcelo Tosatti:
"KVM updates for the 3.9 merge window, including x86 real mode
emulation fixes, stronger memory slot interface restrictions, mmu_lock
spinlock hold time reduction, improved handling of large page faults
on shadow, initial APICv HW acceleration support, s390 channel IO
based virtio, amongst others"
* tag 'kvm-3.9-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (143 commits)
Revert "KVM: MMU: lazily drop large spte"
x86: pvclock kvm: align allocation size to page size
KVM: nVMX: Remove redundant get_vmcs12 from nested_vmx_exit_handled_msr
x86 emulator: fix parity calculation for AAD instruction
KVM: PPC: BookE: Handle alignment interrupts
booke: Added DBCR4 SPR number
KVM: PPC: booke: Allow multiple exception types
KVM: PPC: booke: use vcpu reference from thread_struct
KVM: Remove user_alloc from struct kvm_memory_slot
KVM: VMX: disable apicv by default
KVM: s390: Fix handling of iscs.
KVM: MMU: cleanup __direct_map
KVM: MMU: remove pt_access in mmu_set_spte
KVM: MMU: cleanup mapping-level
KVM: MMU: lazily drop large spte
KVM: VMX: cleanup vmx_set_cr0().
KVM: VMX: add missing exit names to VMX_EXIT_REASONS array
KVM: VMX: disable SMEP feature when guest is in non-paging mode
KVM: Remove duplicate text in api.txt
Revert "KVM: MMU: split kvm_mmu_free_page"
...
Diffstat (limited to 'kernel/sched')
-rw-r--r-- | kernel/sched/core.c | 25 |
1 files changed, 19 insertions, 6 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 053dfd7..f1bdecf 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4374,7 +4374,10 @@ EXPORT_SYMBOL(yield); * It's the caller's job to ensure that the target task struct * can't go away on us before we can do any checks. * - * Returns true if we indeed boosted the target task. + * Returns: + * true (>0) if we indeed boosted the target task. + * false (0) if we failed to boost the target. + * -ESRCH if there's no task to yield to. */ bool __sched yield_to(struct task_struct *p, bool preempt) { @@ -4388,6 +4391,15 @@ bool __sched yield_to(struct task_struct *p, bool preempt) again: p_rq = task_rq(p); + /* + * If we're the only runnable task on the rq and target rq also + * has only one task, there's absolutely no point in yielding. + */ + if (rq->nr_running == 1 && p_rq->nr_running == 1) { + yielded = -ESRCH; + goto out_irq; + } + double_rq_lock(rq, p_rq); while (task_rq(p) != p_rq) { double_rq_unlock(rq, p_rq); @@ -4395,13 +4407,13 @@ again: } if (!curr->sched_class->yield_to_task) - goto out; + goto out_unlock; if (curr->sched_class != p->sched_class) - goto out; + goto out_unlock; if (task_running(p_rq, p) || p->state) - goto out; + goto out_unlock; yielded = curr->sched_class->yield_to_task(rq, p, preempt); if (yielded) { @@ -4414,11 +4426,12 @@ again: resched_task(p_rq->curr); } -out: +out_unlock: double_rq_unlock(rq, p_rq); +out_irq: local_irq_restore(flags); - if (yielded) + if (yielded > 0) schedule(); return yielded; |