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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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6
include/linux/rcutiny.h
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@ -87,6 +87,10 @@ static inline void kfree_call_rcu(struct rcu_head *head,
#ifdef CONFIG_TINY_RCU
static inline void rcu_preempt_note_context_switch(void)
{
}
static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
{
*delta_jiffies = ULONG_MAX;
@ -95,6 +99,7 @@ static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
#else /* #ifdef CONFIG_TINY_RCU */
void rcu_preempt_note_context_switch(void);
int rcu_preempt_needs_cpu(void);
static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
@ -108,6 +113,7 @@ static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
static inline void rcu_note_context_switch(int cpu)
{
rcu_sched_qs(cpu);
rcu_preempt_note_context_switch();
}
/*