From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Date: Fri, 23 May 2014 10:20:42 +0000 Subject: [patch] sched: signedness bug in yield_to() Message-Id: <20140523102042.GA7267@mwanda> List-Id: References: <20130205113751.GA20521@elgon.mountain> In-Reply-To: <20130205113751.GA20521@elgon.mountain> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Ingo Molnar Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org 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 diff --git a/include/linux/sched.h b/include/linux/sched.h index 9112646..7c72b14 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2173,7 +2173,7 @@ 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 927fa33..40f8de4 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4209,7 +4209,7 @@ 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/include/linux/kvm_host.h b/include/linux/kvm_host.h index 970c681..ec4e3bd 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -586,7 +586,7 @@ 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/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 95b4c2b..9458196 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1713,11 +1713,11 @@ 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);