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sched: signedness bug in yield_to()

PATCH In review Dan Carpenter 4 participants 4 messages May 23, 2014 – Jun 5, 2014

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KVM Kernel janitors Scheduler
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Dan Carpenter

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#0 lore raw

PATCH 1/1 sched: 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 <[email protected]>
include/linux/sched.h +1 -1
index 9112646..7c72b14 100644
@@ -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);
 /**
kernel/sched/core.c +1 -1
index 927fa33..40f8de4 100644
@@ -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;
include/linux/kvm_host.h +1 -1
index 970c681..ec4e3bd 100644
@@ -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);
virt/kvm/kvm_main.c +2 -2
index 95b4c2b..9458196 100644
@@ -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);
maintainer
#1 lore raw
Quoted 7 lines · Dan Carpenter

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 <[email protected]>

Thanks Dan!

merge bot
#3 lore raw

[tip:sched/core] sched: Fix signedness bug in yield_to()

In reply to Dan Carpenter
sched: Fix signedness bug in yield_to()
Commit-ID:  fa93384f40deeb294fd29f2fdcadbd0ebc2dedf1
Gitweb:     http://git.kernel.org/tip/fa93384f40deeb294fd29f2fdcadbd0ebc2dedf1
Author:     Dan Carpenter <[email protected]>
AuthorDate: Fri, 23 May 2014 13:20:42 +0300
Committer:  Ingo Molnar <[email protected]>
CommitDate: Thu, 5 Jun 2014 11:52:13 +0200

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 <[email protected]>
Reviewed-by Raghavendra <[email protected]>
Signed-off-by Peter Zijlstra <[email protected]>
Cc Gleb Natapov <[email protected]>
Cc Linus Torvalds <[email protected]>
Cc Paolo Bonzini <[email protected]>
Cc [email protected]
Link http://lkml.kernel.org/r/20140523102042.GA7267@mwanda open here
Signed-off-by Ingo Molnar <[email protected]>
---
 include/linux/kvm_host.h | 2 +-
 include/linux/sched.h    | 2 +-
 kernel/sched/core.c      | 2 +-
 virt/kvm/kvm_main.c      | 4 ++--
 4 files changed, 5 insertions(+), 5 deletions(-)
include/linux/kvm_host.h +1 -1
index 7d21cf9..3c4bcf1 100644
@@ -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
index 0f91d00..6790c3b 100644
@@ -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
index 321d800..afcc842 100644
@@ -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
index 56baae8..86d1c45 100644
@@ -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);