The following commit has been merged into the locking/core branch of tip:
Commit-ID: c0bed69daf4b67809b58cc7cd81a8fa4f45bc161
Gitweb: https://git.kernel.org/tip/c0bed69daf4b67809b58cc7cd81a8fa4f45bc161
Author: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
AuthorDate: Fri, 03 Dec 2021 15:59:34 +08:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Sat, 04 Dec 2021 10:56:25 +01:00
locking: Make owner_on_cpu() into <linux/sched.h>
Move the owner_on_cpu() from kernel/locking/rwsem.c into
include/linux/sched.h with under CONFIG_SMP, then use it
in the mutex/rwsem/rtmutex to simplify the code.
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211203075935.136808-2-wangkefeng.wang@xxxxxxxxxx
---
include/linux/sched.h | 9 +++++++++
kernel/locking/mutex.c | 11 ++---------
kernel/locking/rtmutex.c | 5 ++---
kernel/locking/rwsem.c | 9 ---------
4 files changed, 13 insertions(+), 21 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 78c351e..ff609d9 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2171,6 +2171,15 @@ extern long sched_getaffinity(pid_t pid, struct cpumask *mask);
#endif
#ifdef CONFIG_SMP
+static inline bool owner_on_cpu(struct task_struct *owner)
+{
+ /*
+ * As lock holder preemption issue, we both skip spinning if
+ * task is not on cpu or its cpu is preempted
+ */
+ return owner->on_cpu && !vcpu_is_preempted(task_cpu(owner));
+}
+
/* Returns effective CPU energy utilization, as seen by the scheduler */
unsigned long sched_cpu_util(int cpu, unsigned long max);
#endif /* CONFIG_SMP */
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index db19136..5e35859 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -367,8 +367,7 @@ bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner,
/*
* Use vcpu_is_preempted to detect lock holder preemption issue.
*/
- if (!owner->on_cpu || need_resched() ||
- vcpu_is_preempted(task_cpu(owner))) {
+ if (!owner_on_cpu(owner) || need_resched()) {
ret = false;
break;
}
@@ -403,14 +402,8 @@ static inline int mutex_can_spin_on_owner(struct mutex *lock)
* structure won't go away during the spinning period.
*/
owner = __mutex_owner(lock);
-
- /*
- * As lock holder preemption issue, we both skip spinning if task is not
- * on cpu or its cpu is preempted
- */
-
if (owner)
- retval = owner->on_cpu && !vcpu_is_preempted(task_cpu(owner));
+ retval = owner_on_cpu(owner);
/*
* If lock->owner is not set, the mutex has been released. Return true
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index f896208..0c1f2e3 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1382,9 +1382,8 @@ static bool rtmutex_spin_on_owner(struct rt_mutex_base *lock,
* for CONFIG_PREEMPT_RCU=y)
* - the VCPU on which owner runs is preempted
*/
- if (!owner->on_cpu || need_resched() ||
- rt_mutex_waiter_is_top_waiter(lock, waiter) ||
- vcpu_is_preempted(task_cpu(owner))) {
+ if (!owner_on_cpu(owner) || need_resched() ||
+ rt_mutex_waiter_is_top_waiter(lock, waiter)) {
res = false;
break;
}
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index c51387a..b92d0a8 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -613,15 +613,6 @@ static inline bool rwsem_try_write_lock_unqueued(struct rw_semaphore *sem)
return false;
}
-static inline bool owner_on_cpu(struct task_struct *owner)
-{
- /*
- * As lock holder preemption issue, we both skip spinning if
- * task is not on cpu or its cpu is preempted
- */
- return owner->on_cpu && !vcpu_is_preempted(task_cpu(owner));
-}
-
static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem)
{
struct task_struct *owner;
|