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Revert "rcu: Move PREEMPT_RCU preemption to switch_to() invocation"

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This reverts commit 616c310e83.
(Move PREEMPT_RCU preemption to switch_to() invocation).
Testing by Sasha Levin <levinsasha928@gmail.com> showed that this
can result in deadlock due to invoking the scheduler when one of
the runqueue locks is held.  Because this commit was simply a
performance optimization, revert it.

Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
This commit is contained in:
Paul E. McKenney
2012-07-02 07:08:42 -07:00
parent 6887a4131d
commit cba6d0d64e
8 changed files with 19 additions and 16 deletions
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10
include/linux/sched.h
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@@ -1871,22 +1871,12 @@ static inline void rcu_copy_process(struct task_struct *p)
INIT_LIST_HEAD(&p->rcu_node_entry);
}
static inline void rcu_switch_from(struct task_struct *prev)
{
if (prev->rcu_read_lock_nesting != 0)
rcu_preempt_note_context_switch();
}
#else
static inline void rcu_copy_process(struct task_struct *p)
{
}
static inline void rcu_switch_from(struct task_struct *prev)
{
}
#endif
#ifdef CONFIG_SMP