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Commit fa93384f authored by Dan Carpenter's avatar Dan Carpenter Committed by Ingo Molnar
Browse files

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: default avatarDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: default avatarRaghavendra <raghavendra.kt@linux.vnet.ibm.com>
Signed-off-by: default avatarPeter 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: default avatarIngo Molnar <mingo@kernel.org>
parent 2538d960

include/linux/kvm_host.h

+1 −1
Original line number Diff line number Diff line
@@ -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);

include/linux/sched.h

+1 −1
Original line number Diff line number Diff line
@@ -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);

/**

kernel/sched/core.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

virt/kvm/kvm_main.c

+2 −2
Original line number Diff line number Diff line
@@ -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);