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-rw-r--r--kernel/rtmutex.c51
1 files changed, 25 insertions, 26 deletions
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index 3e13a1e5856..4ab17da46fd 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -251,6 +251,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
/* Grab the next task */
task = rt_mutex_owner(lock);
+ get_task_struct(task);
spin_lock_irqsave(&task->pi_lock, flags);
if (waiter == rt_mutex_top_waiter(lock)) {
@@ -269,7 +270,6 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
__rt_mutex_adjust_prio(task);
}
- get_task_struct(task);
spin_unlock_irqrestore(&task->pi_lock, flags);
top_waiter = rt_mutex_top_waiter(lock);
@@ -409,7 +409,7 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
struct task_struct *owner = rt_mutex_owner(lock);
struct rt_mutex_waiter *top_waiter = waiter;
unsigned long flags;
- int boost = 0, res;
+ int chain_walk = 0, res;
spin_lock_irqsave(&current->pi_lock, flags);
__rt_mutex_adjust_prio(current);
@@ -433,25 +433,23 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
plist_add(&waiter->pi_list_entry, &owner->pi_waiters);
__rt_mutex_adjust_prio(owner);
- if (owner->pi_blocked_on) {
- boost = 1;
- /* gets dropped in rt_mutex_adjust_prio_chain()! */
- get_task_struct(owner);
- }
- spin_unlock_irqrestore(&owner->pi_lock, flags);
- }
- else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock)) {
- spin_lock_irqsave(&owner->pi_lock, flags);
- if (owner->pi_blocked_on) {
- boost = 1;
- /* gets dropped in rt_mutex_adjust_prio_chain()! */
- get_task_struct(owner);
- }
+ if (owner->pi_blocked_on)
+ chain_walk = 1;
spin_unlock_irqrestore(&owner->pi_lock, flags);
}
- if (!boost)
+ else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock))
+ chain_walk = 1;
+
+ if (!chain_walk)
return 0;
+ /*
+ * The owner can't disappear while holding a lock,
+ * so the owner struct is protected by wait_lock.
+ * Gets dropped in rt_mutex_adjust_prio_chain()!
+ */
+ get_task_struct(owner);
+
spin_unlock(&lock->wait_lock);
res = rt_mutex_adjust_prio_chain(owner, detect_deadlock, lock, waiter,
@@ -532,7 +530,7 @@ static void remove_waiter(struct rt_mutex *lock,
int first = (waiter == rt_mutex_top_waiter(lock));
struct task_struct *owner = rt_mutex_owner(lock);
unsigned long flags;
- int boost = 0;
+ int chain_walk = 0;
spin_lock_irqsave(&current->pi_lock, flags);
plist_del(&waiter->list_entry, &lock->wait_list);
@@ -554,19 +552,20 @@ static void remove_waiter(struct rt_mutex *lock,
}
__rt_mutex_adjust_prio(owner);
- if (owner->pi_blocked_on) {
- boost = 1;
- /* gets dropped in rt_mutex_adjust_prio_chain()! */
- get_task_struct(owner);
- }
+ if (owner->pi_blocked_on)
+ chain_walk = 1;
+
spin_unlock_irqrestore(&owner->pi_lock, flags);
}
WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
- if (!boost)
+ if (!chain_walk)
return;
+ /* gets dropped in rt_mutex_adjust_prio_chain()! */
+ get_task_struct(owner);
+
spin_unlock(&lock->wait_lock);
rt_mutex_adjust_prio_chain(owner, 0, lock, NULL, current);
@@ -592,10 +591,10 @@ void rt_mutex_adjust_pi(struct task_struct *task)
return;
}
- /* gets dropped in rt_mutex_adjust_prio_chain()! */
- get_task_struct(task);
spin_unlock_irqrestore(&task->pi_lock, flags);
+ /* gets dropped in rt_mutex_adjust_prio_chain()! */
+ get_task_struct(task);
rt_mutex_adjust_prio_chain(task, 0, NULL, NULL, task);
}