sched: Fix signedness bug in yield_to()

yield_to() is supposed to return -ESRCH if there is no task to
yield to, but because the type is bool that is the same as returning
true.

The only place I see which cares is kvm_vcpu_on_spin().

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Raghavendra <raghavendra.kt@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Link: http://lkml.kernel.org/r/20140523102042.GA7267@mwanda
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 7d21cf9f43806cae2c6b14363e83cd628366acdb..3c4bcf146159f25939a29b8fe75b4c1e3889fe96 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -584,7 +584,7 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn);
 
 void kvm_vcpu_block(struct kvm_vcpu *vcpu);
 void kvm_vcpu_kick(struct kvm_vcpu *vcpu);
-bool kvm_vcpu_yield_to(struct kvm_vcpu *target);
+int kvm_vcpu_yield_to(struct kvm_vcpu *target);
 void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu);
 void kvm_load_guest_fpu(struct kvm_vcpu *vcpu);
 void kvm_put_guest_fpu(struct kvm_vcpu *vcpu);

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0f91d00efd87d2a400e683af11514dc471c99e22..6790c3b4207221ca4b672c171196b551646d7919 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2180,7 +2180,7 @@ static inline void sched_autogroup_fork(struct signal_struct *sig) { }
 static inline void sched_autogroup_exit(struct signal_struct *sig) { }
 #endif
 
-extern bool yield_to(struct task_struct *p, bool preempt);
+extern int yield_to(struct task_struct *p, bool preempt);
 extern void set_user_nice(struct task_struct *p, long nice);
 extern int task_prio(const struct task_struct *p);
 /**

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 321d800e4baa24f82db15b48c5e3af0a253a404d..afcc84234a3e8dadc8ee0e95b2890944a9bac45a 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4195,7 +4195,7 @@ EXPORT_SYMBOL(yield);
  *     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)
+int __sched yield_to(struct task_struct *p, bool preempt)
 {
        struct task_struct *curr = current;
        struct rq *rq, *p_rq;

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 56baae8c2f56baf0f41bb7bb24b0b12679267d20..86d1c457458d46ce5182cf3d549eec0800baf8d6 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1708,11 +1708,11 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
 EXPORT_SYMBOL_GPL(kvm_vcpu_kick);
 #endif /* !CONFIG_S390 */
 
-bool kvm_vcpu_yield_to(struct kvm_vcpu *target)
+int kvm_vcpu_yield_to(struct kvm_vcpu *target)
 {
        struct pid *pid;
        struct task_struct *task = NULL;
-       bool ret = false;
+       int ret = 0;
 
        rcu_read_lock();
        pid = rcu_dereference(target->pid);